Colorectal cancer

Abstract

Colorectal cancer had a low incidence several decades ago. However, it has become a predominant cancer and now accounts for approximately 10% of cancer-related mortality in western countries. The ‘rise’ of colorectal cancer in developed countries can be attributed to the increasingly ageing population, unfavourable modern dietary habits and an increase in risk factors such as smoking, low physical exercise and obesity. New treatments for primary and metastatic colorectal cancer have emerged, providing additional options for patients; these treatments include laparoscopic surgery for primary disease, more-aggressive resection of metastatic disease (such as liver and pulmonary metastases), radiotherapy for rectal cancer and neoadjuvant and palliative chemotherapies. However, these new treatment options have had limited impact on cure rates and long-term survival. For these reasons, and the recognition that colorectal cancer is long preceded by a polypoid precursor, screening programmes have gained momentum. This Primer provides an overview of the current state of art knowledge on the epidemiology and mechanisms of colorectal cancer, as well as on diagnosis and treatment.

Full text

We live in an era with improved worldwide a verage l iving
standards and increased access to adequate health care
that has considerably improved the diagnosis and treat-
ment of diseases. These measures have had an effect on
the average life expectancy in most regions of the world.
However, although death rates from communicable dis-
eases have improved globally as a result of these medical
improvements, cancer-related mortality has increased by
almost 40% over the past 40years. Afurther 60% increase
is expected in the next 15years,with 13m illion people
estimated to die of c ancer in 2030 (REF.1). The main causes
of cancer-related mortality have also changed, attribut-
able to alterations in disease incidence, the introduction
of screening programmes and therapeutic improvements.
Colorectal cancer was rather rare in 1950, but has become
a predominant cancer in western countries, now account-
ing for approximately 10% of cancer-related mortality.
Reasons explaining this increased incidence include an
ageing population and the preponderance of poor diet-
ary habits, smoking, low physical activity and o besity
in western countries. The change in incidence is not
only apparent in the rates of sporadic disease but also
in some familial cancer syndromes. Indeed, given that
the rates of Helicobacter pylori infection (a causative fac-
tor of gastric cancer) have fallen dramatically, colorectal
cancer is now the predominant presentation of Lynch
syndrome (a hereditary non-polyposis type of colo rectal
cancer), whereas c arriers of this syndrome used to be
p redominantly affected by gastriccancer2–4.
New treatments for primary and metastatic colorectal
cancer have been developed and include: laparoscopic
surgery for primary disease; resection of metastatic
disease affecting, for example, the liver and lungs; radio-
therapy for rectal cancer and some forms of metastatic
disease; and neoadjuvant and palliative chemotherapy5–7.
Despite advances in surgical and medical therapies, cure
rates and long-term survival have changed little in the
past several decades. Against this background, and given
that colorectal cancer is preceded by a polypoid precur-
sor (FIG.1), screening programmes for early detection
have gained momentum.
Indeed, screening is expected to have a substantial
impact on colorectal cancer incidence and mortality
in the next 15years, an affect that is unlikely to come
from lifestyle interventions or from new therapeutics.
Screening will only make these improvements with
high uptake; accordingly, major improvements in non-
invasive screening (for example, faecal immunochemical
testing and faecal DNA testing) are being investigated
as alternatives to the current gold-standard, but inva-
sive, screening methodology — colonoscopy. Alongside
these advances, the quality of screening colonoscopy
has undergone substantial improvement in terms of
t echnical changes and training, and quality assurance8,9.
In this Primer, we provide an overview of the cur-
rent knowledge on the epidemiology and mechanisms
underlying colorectal cancer, as well as on diagnosis and
treatment, including surgical and medical approaches.
Epidemiology
Colorectal cancer is the second-most and third-most
common cancer in women and men, respectively. In2012,
614,000 women (9.2% of all new cancer cases) and
746,000 men (10% of new cancer cases) were diagnosed
Correspondence to E.J.K.
e-mail: e.j.kuipers@
erasmusmc.nl
Erasmus MC University
Medical Center,
s-Gravendijkwal 230,
3015CE Rotterdam,
TheNetherlands.
Article number: 15065
doi:10.1038/nrdp.2015.65
Published online
5 November 2015
Colorectal cancer
Ernst J.Kuipers1, William M.Grady2,3, David Lieberman4, Thomas Seufferlein5,
JosephJ.Sung6, Petra G.Boelens7, Cornelis J.H.van de Velde7 and Toshiaki Watanabe8
Abstract | Colorectal cancer had a low incidence several decades ago. However, it has become a
predominant cancer and now accounts for approximately 10% of cancer-related mortality in western
countries. The ‘rise’ of colorectal cancer in developed countries can be attributed to the increasingly ageing
population, unfavourable modern dietary habits and an increase in risk factors, such as smoking, low
physical exercise and obesity. New treatments for primary and metastatic colorectal cancer have emerged,
providing additional options for patients; these treatments include laparoscopic surgery for primary
disease, more-aggressive resection of metastatic disease (such as liver and pulmonary metastases),
radiotherapy for rectal cancer, and neoadjuvant and palliative chemotherapies. However, these new
treatment options have had limited impact on cure rates and long-term survival. For these reasons, and the
recognition that colorectal cancer is long preceded by a polypoid precursor, screening programmes have
gained momentum. This Primer provides an overview of the current state of the art of knowledge on the
epidemiology and mechanisms of colorectal cancer, as well as on diagnosis and treatment.
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withcolorectal cancer worldwide10. Combined, in both
sexes, colorectal cancer is the third-most common
c ancer and accounts for 9.7% of all cancers excluding
non- melanoma skin cancer. More than half of the cases
occur in more-developed regions of world. The age-
standardized incidence rate (ASRi) of colorectal cancer
is higher in men (20.6 per 100,000 individuals) than in
women (14.3 per 100,000 individuals). The majority of
patients with spora dic cancer are >50years of age, with
75% of patients with rectal cancer and 80% of patients
with colon cancer being ≥60years of age at the time
ofdiagnosis.
Incidence varies geographically, with the highest
incidence in Australia and New Zealand (ASRi: 44.8
and 32.2 per 100,000 men and women, respectively),
whereas Western Africa (ASRi: 4.5 and 3.8 per 100,000)
has the lowest incidence (FIG.2). More-developed regions
(Europe, Northern America, Australia, New Zealand
and Japan; combined ASRi: 29.2 per 100,000) have a
higher incidence than less-developed regions (all regions
of Africa, Asia (excluding Japan), Latin America and the
Caribbean, Melanesia, Micronesia and Polynesia; com-
bined ASRi: 11.7 per 100,000)10. The seven world regions
can be ranked according to increasing ASRi: from Africa
(6.3 per 100,000), Asia (13.7 per 100,000), Latin America
and the Caribbean (14.0 per 100,000), Micronesia and
Polynesia (15.0 per 100,000), Northern America (26.1
per 100,000), Europe (29.5 per 100,000), to Australia
and New Zealand (34.8 per 100,000)10. Within each of
these regions, the ASRi of colorectal cancer can show
marked variation. In Europe, Albania (8.4 per 100,000)
and Ukraine (23.4 per 100,000) have a lower incidence,
whereas Slovakia (42.7 per 100,000), Hungary (42.3 per
100,000) and Denmark (40.5 per 100,000) have high
incidence. Asia has the greatest diversity with regard
to the ASRi of colorectal cancer. The incidence is high
inSouth Korea (45.0 per 100,000), Singapore (33.7 per
100,000) and Japan (32.2 per 100,000), but much lower
in Nepal (3.2 per 100,000), Bhutan (3.5 per 100,000) and
India (6.1 per 100,000). These variations are associated
with different socioeconomic levels11.
In 2013, 771,000 people died as a result of colorectal
cancer globally12, making the disease the fourth-most
common cause of cancer-related death worldwide after
lung, liver and stomach cancer12. The age-standardized
mortality rate (ASRm) of colorectal cancer in differ-
ent countries reflects disease incidence, which explains
why the ASRm is higher in men (10.0 per 100,000) than
in women (6.9 per 100,000). Mortality also depends
on thestage distribution at diagnosis, which is influ-
enced bythe availability of a population screening pro-
gramme and by the level of care in each country. The
ASRm is almost twofold higher in more-developed
regions(11.6 per 100,000) than in less-developed regions
(6.6per100,000). The ASRm in both sexes ranged from
3.3 per 100,000 people in Western Africa to 14.9 per
100,000 people in Central and Eastern Europe; in men,
this value ranged from 3.5 per 100,000 people in Western
Africa to 20.3 in Central and Eastern Europe, whereas
inwomen, ASRm ranged from 3.0 per 100,000 people in
Western Africa to 11.7 per 100,000 people in Central and
Eastern Europe. That is, Western Africa showed the low-
est age-standardized mortality in the world and Central
and Eastern Europe exhibited the highest mortality in the
world, in both men and women. Worldwide, mortality
due to colorectal cancer has increased by 57% between
1990 and 2013 (REF.12). Since the 1980s, in several
c ountries in Europe, North America and Asia, mortality
has tended to decrease. This decrease might be attrib-
utable to the introduction of colonoscopy, which has
improved the detection and treatment of early lesions.
Author addresses
1Erasmus MC University Medical Center,
s‑Gravendijkwal230, 3015 CE Rotterdam, The Netherlands.
2Clinical Research Division, Fred Hutchinson Cancer
Research Center, Seattle, Washington, USA.
3Department of Medicine, University of Washington
School of Medicine, Seattle, Washington, USA.
4Division of Gastroenterology and Hepatology, Oregon
Health and Science University, Portland, Oregon, USA.
5Department of Internal Medicine I, University of Ulm,
Ulm,Germany.
6Department of Medicine and Therapeutics, Chinese
University of Hong Kong, Hong Kong, China.
7Department of Surgery, Leiden University Medical Center,
Leiden, The Netherlands.
8Department of Surgical Oncology and Vascular Surgery,
University of Tokyo and the University of Tokyo Hospital,
Tokyo, Japan.
Nature Reviews | Disease Primers
abc
Figure 1 | Colorectal neoplasia at different stages. a | A small sessile adenoma. b | An advanced, larger sessile
adenoma. c | A large, dish-shaped, ulcerating sigmoid carcinoma. The tumour covers most of the circumference, but has
not yet led to substantial obstruction of the lumen.
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Risk factors
Both genetic and environmental factors play an impor-
tant part in the aetiology of colorectal cancer. The
majority of colorectal cancers are sporadic; approxi-
mately three-quarters of patients have a negative f amily
history. In most western populations, the average life-
time risk for colorectal cancer is in the range of 3–5%.
However, this risk almost doubles in individuals with a
first-degree family member with colorectal cancer who
was diagnosed at 50–70years of age; the risk triples if
the first-degree relative was <50years of age at diag-
nosis. Risk further increases in individuals who have
two or more affected family members. For sporadic
colorectal cancer, this increased risk in the presence of
affected family at least in part reflects low-penetrance
genetic factors. Accordingly, positive family history
has a role in a pproximately 15–20% of patients with
colorectalcancer.
Indeed, a specific subgroup of the patient popula-
tion is formed by those affected by a hereditary colo-
rectal cancer syndrome, accounting for 5–10% of all
patients. The most common syndrome in this category
is Lynch syndrome. This syndrome is caused by a muta-
tion in one of the DNA mismatch-repair genes: MLH1,
MSH2, MSH6, PMS2 or EPCAM. Impaired mismatch
repair during replication gives rise to the accumula-
tion of DNA mutations, which occur, in particular, in
microsatellite DNA fragments with repetitive nucleo-
tide sequences. This microsatellite instability (MSI)
can be identified by PCR testing, which compares
normal and tumour DNA of the same patient. Patients
with Lynch syndrome used to be identified by clinico-
pathological criteria, such as the Amsterdam and
Bethesda criteria4,13. However, clinical practice is shift-
ing towards unrestricted testing of tumour m aterial of
all patients diagnosed before 70years of age by MSI
PCR and immunohistochemistry for lack of e xpression
of s pecific mismatch-repairproteins14,15.
The second-most common hereditary colorectal
cancer syndrome is familial adenomatous polyposis.
This syndrome is caused by mutations in the adeno-
matous polyposis coli (APC) gene, which controls the
activity of the WNT signalling pathway4. Most patients
with familial adenomatous polyposis develop very large
numbers of colorectal adenomas and subsequent colo-
rectal cancer at a young age. Other hereditary colo rectal
cancer syndromes include polyposis associated with
mutations in the mutY DNA glycosylase (MUTYH)
gene, Peutz–Jeghers syndrome, serrated polyposis and
juvenile polyposis; the diagnosis and management of
which have been discussed elsewhere4.
Chronic colitis due to inflammatory bowel disease
(IBD) is also associated with increased risk of colo-
rectal cancer. This risk increases with longer duration
Nature Reviews | Disease Primers
Central Africa
Incidence
m: 4.7, f: 4.8
Mortality
m: 3.8, f: 3.9
Southern Africa
Incidence
m: 14.2, f: 8.7
Mortality
m: 10.0, f: 5.8
Eastern Africa
Incidence
m: 7.1, f: 6.1
Mortality
m: 5.5, f: 4.6
Northern Africa
Incidence
m: 8.5, f: 6.9
Mortality
m: 5.6, f: 4.5
Western Africa
Incidence
m: 4.5, f: 3.8
Mortality
m: 3.5, f: 3.0
Northern America
Incidence
m: 30.1, f: 22.7
Mortality
m: 11.3, f: 7.8
Northern Europe
Incidence
m: 36.5, f: 25.3
Mortality
m: 13.4, f: 9.2
Western Europe
Incidence
m: 39.1, f: 24.9
Mortality
m: 13.3, f: 8.3
South-central Asia
Incidence
m: 7.0, f: 5.2
Mortality
m: 5.1, f: 3.8
Eastern Asia
Incidence
m: 22.4, f: 14.6
Mortality
m: 10.2, f: 6.8
South-eastern
Asia
Incidence
m: 15.2, f: 10.2
Mortality
m: 9.7, f: 6.4
Melanesia
Incidence
m: 11.1, f: 6.9
Mortality
m: 7.7, f: 4.9
Australia and
New Zealand
Incidence
m: 44.8, f: 32.2
Mortality
m: 11.6, f: 8.5
Western Asia
Incidence
m: 17.6, f: 12.4
Mortality
m: 10.0, f: 7.1
South America
Incidence
m: 17.1, f: 14.6
Mortality
m: 9.4, f: 7.7
Caribbean
Incidence
m: 16.3, f: 16.6
Mortality
m: 9.1, f: 9.1
Central America
Incidence
m: 8.8, f: 7.1
Mortality
m: 4.9, f: 3.8
Micronesia
Incidence
m: 24.8, f: 16.6
Mortality
m: 10.5, f: 6.4
Central and
Eastern Europe
Incidence
m: 34.5, f: 21.7
Mortality
m: 20.3, f: 11.7
Southern Europe
Incidence
m: 39.5, f: 24.1
Mortality
m: 15.4, f: 8.7
Figure 2 | The age-standardized incidence and mortality rates in men and women (per 100,000 people) across
geographical zones. Rates are consistently higher in males (m) than in females (f), and vary considerably between
regions10. Highest rates occur in Australia and New Zealand, Europe and Northern America.
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of IBD16. IBD explains only 1% of colorectal cancers in
western populations, and a range of studies suggest that
the incidence of colorectal cancer in those with IBD is
decreasing because of effective anti-inflammatory treat-
ments and improved surveillance17,18, although this
observation is not yet unanimous19.
A range of environmental — largely modifiable
— lifestyle factors influence the risk of developing
colorectal cancer. The risk is increased by smoking,
alcohol intake and increased body weight. With each
unit increase of the body mass index, the risk for colo-
rectal cancer increases by 2–3%20. In close conjunc-
tion, patients with type2 diabetes mellitus also have an
increased risk of colorectal cancer21. Moderate alcohol
consumption (2–3 units per day) has been estimated
to increase risk by 20%, whereas even higher alcohol
consumption is associated with an up to 50% increased
risk22. Prolonged heavy smoking has an effect of similar
magnitude23,24. Intake of red meat and processed meat
increases the risk of colorectal cancer by an estimated
1.16-fold per 100 g increase of daily intake25. By con-
trast, the consumption of milk, whole grains, fresh
fruits and vegetables, as well as an intake of calcium,
fibre, multivitamins and vitaminD, decrease the risk
of colorectal cancer. The decrease of risk is estimated
to be approximately 10% per daily intake of every 10 g
of fibre, 300 mg of calcium or 200 ml of milk25,26. Daily
physical activity for 30minutes has a similar magnitude
of effect20,27. Low-dose aspirin has also been associated
with decreased risk of colorectalcancer28.
The prevalence of these modifiable lifestyle factors
can explain, to a considerable extent, the geographical
and socioeconomic differences in colorectal cancer inci-
dence29. Several studies have estimated that 16–71% of
colorectal cancers in Europe and the United States are
attributable to lifestyle factors30–32. Any benefit from
lifestyle changes can be augmented by regular intake
of aspirin and other NSAIDs28; however, this effect
seems to depend on the host genotype33,34. Statin use
might have a small preventive effect on the incidence
of colorectal cancer35,36, as does hormone therapy in
p ostmenopausal women37.
The various environmental factors that influence
colorectal carcinogenesis is probably reflected in the
heterogeneity of colorectal cancer, and has stimulated
research into the field of ‘molecular pathological epi-
demiology’, which focuses on the correlation between
environmental and genetic factors, and between molec-
ular tumour characteristics and disease progression38.
Further research into the correlation between colonic
microbiota and colorectal cancer will probably provide
further insights (see below).
Mechanisms/pathophysiology
The environmental and genetic factors that cause
colorectal cancer do so by promoting the acquisition
of hallmark behaviours of cancer (BOX1) in colon epi-
thelial cells39,40. One way these hallmark cancer traits
are acquired is through the progressive accumulation
of genetic mutations and epigenetic alterations that
activate oncogenes and inactivate tumour suppressor
genes. The loss of genomic and/or epigenomic stability
has been observed in the majority of early neoplastic
lesions in the colon (namely, aberrant crypt foci, ade-
nomas and serrated polyps) and is probably a central
molecular and pathophysiological event in the initia-
tion and formation of colorectal cancer41,42. The loss
of genomic and epigenomic stability accelerates the
accumulation of mutations and epigenetic alterations
in oncogenes and tumour suppressor genes, which drive
the malignant transformation of colon cells through
rounds of clonal expansion that select for those cells
with the most aggressive and malignant behaviour43–45.
A prevailing paradigm is that the cell of origin of most
colorectal cancers is a stem cell or stem cell-like cell that
resides in the base of the colon crypts46. In this model,
mutations in oncogenes and tumour suppressor genes
in these cells lead to the formation of cancer stem cells,
which are essential for the initiation and maintenance
of atumour.
In the colon, the evolution of normal epithelial cells
to adenocarcinoma by and large follows a predictable
progression of histological and concurrent epigenetic
and genetic changes (FIG.3). In the ‘classic’ colorectal
cancer formation model, the vast majority of cancers
arise from a polyp beginning with an aberrant crypt,
which then evolves into an early adenoma (<1 cm in size,
with tubular or tubulovillous histology). The adenoma
then progresses to an advanced adenoma (>1 cm in size,
and/or with villous histology) before finally becoming
a colorectal cancer. This process is driven by the accu-
mulation of mutations and epi genetic alter ations and
takes 10–15years to occur but can progress more rap-
idly in certain settings (for example, in patients with
Lynch syndrome)47. Notably, although the histo logy of
conventional tubular adenomas is fairly homogeneous,
the molecular biology of these polyps are heterogene-
ous, which might explain why some adenomas progress
to colorectal cancer (approximately 10% of polyps) and
some do not48,49.
Box 1 | Hallmarks of cancer*
• Avoiding immune destruction: immune suppression in the tumour microenvironment
by induction of local cytokines
• Evading growth suppressors: mutation and downregulation of growth‑inhibiting
factors and their receptors
• Genome instability and mutation: inactivation of DNA repair mechanisms
• Enabling replicative immortality: inhibition of mechanisms that induce senescence
and induction of telomerase activity
• Deregulating cellular energetics: aerobic glycolysis (Warburg phenomenon)
andglutaminolysis
• Tumour‑promoting inflammation: induction of growth‑promoting and
angiogenesis‑promoting factors by secreted proteins made by local inflammatory cells
• Inducing angiogenesis: induction of the formation of new blood vessels
• Resisting cell death: escape from autonomous and paracrine mediators of apoptosis
and other forms of cell death (necrosis or necroptosis)
• Activating invasion and metastasis: remodelling of the extracellular matrix to
promote cell motility and induction of epithelial–mesenchymal transition
*See REFS39,40.
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Until 5–10years ago, tubular and tubulovillous
adenomatous polyps were thought to be the only
lesions that were capable of progressing to cancer.
However, some colorectal cancers have been shown to
evolve from a subset of polyps called sessile serrated
polyps, which account for approximately 5–10% of
all polyps. These serrated polyps arise by molecular
and histological events that are distinct from tubular
adenomas50–52 and are classified into three categories:
hyperplastic polyps, sessile serrated adenomas and
traditional serrated adenomas53. The sessile serrated
polyps have the potential to transform into colorectal
cancers through the following sequence: hyperplastic
polyp to sessile serrated polyp to adenocarcinoma50,54.
Furthermore,serratedpolyps that arise in the right
colon (which includes the caecum, ascending colon and
transverse colon) commonly show MSI and a form of
epigenetic instability characterized by excessive aber-
rant CpG island DNA methylation, termed the CpG
island methyl ator pheno type (CIMP). By contrast,
polyps that arise in the left colon (which includes the
descending colon, sigmoid colon and rectum) are
typically microsatellite stable but frequently carry
mutations in KRAS, and a subset of these polyps have
an attenuated form of theCIMP51,52,55.
Given these molecular differences in the polyps and
cancers they evolve into, a classification system for colo-
rectal cancer has been proposed, with four subgroups
of differing molecular features: hypermutable micro-
satellite unstable, hypermutable microsatellite stable,
microsatellite stable or chromosome unstable, and
CIMP cancers42,56. The frequency of specific mutations
can vary dramatically between the molecular subclasses,
suggesting that each has its own set of cooperating driv-
ers56. However, the specific mutations and epigenetic
alterations that define these molecular subgroups are
still being determined. Some mutations, such as those in
APC and SMAD family member4 (SMAD4), are com-
mon among all the molecular subgroups — suggesting
a central role in colorectal cancer in general — whereas
others are restricted to one subgroup (for example,
BRAF in CIMP colorectal cancers)57.
In colorectal cancer, substantial heterogeneity in
the specific mutations is evident between tumours,
CTNNB1
APC
Normal epithelium
KRAS
BRAF PIK3CA TGFBR2
WNT signalling
LRP5
FZD10
SFRP
FAM123B
MAPK signalling
KRAS
BRAF
NRAS
ERBB2
ERBB3
PI3K signalling
PTEN
PI3KCA
TGFβ signalling
TGFBR2 p53 signalling
NRAS
KRAS SMAD4 TP53
Adenoma cancer
(CIN and MSI
in Lynch syndrome)
Serrated polyps cancer
(CIMP and
sporadic MSI)
Nature Reviews | Disease Primers
Figure 3 | The polyp to colorectal cancer sequences. Currently, two discrete normal colon to colorectal cancer
sequences have been identified. Both sequences involve the progression of normal colon epithelial cells to aberrant
crypt foci, followed by early and advanced polyps with subsequent progression to early cancer and then advanced
cancer. The ‘classic’ or traditional pathway (top) involves the development of tubular adenomas that can progress to
adenocarcinomas. An alternate pathway (bottom) involves serrated polyps, and their progression to serrated
colorectal cancer has been described in the past 5–10years. The genes mutated or epigenetically altered are
indicated in each sequence; some genes are shared between the two pathways, whereas others are unique (for
example, BRAF mutations and CpG island methylator phenotype (CIMP) only occur in the serrated pathway). The
signalling pathways deregulated during the progression sequence are also shown, with the width of the arrow
reflecting the significance of the signalling pathway in tumour formation. APC, adenomatous polyposis coli; CIN,
chromosomal instability; CTNNB1, catenin-β1; FAM123B, family with sequence similarity 123B (also known as AMER1);
FZD10, frizzled class receptor 10; LRP5, low-density lipoprotein receptor-related protein 5; MAPK,
mitogen-activatedprotein kinase; MSI, microsatellite instability; PI3K, phosphatidylinositol 3-kinase; PI3KCA,
phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit-α; PTEN, phosphatase and tensin homologue;
SFRP,secreted frizzled-related protein; SMAD4, SMAD family member 4; TGFβ, transforming growth factor-β;
TGFBR2, TGFβ receptor 2. Figure from REF.224, Nature Publishing Group.
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Table 1 | Common genetic and epigenetic alterations in colorectal cancer*
Gene or
biomarker
Chromo some Function Molecular
lesion
Frequency
(%)
Predictive? Prognostic? Diagnostic?
Tumour suppressors
APC 5Regulates the WNT
signalling pathway
Inactivating
mutations
40–70 No No Familial
adenomatous
polyposis
ARID1A 1Member of the SWI/
SNF family, and regulates
chromatin structure and
gene transcription
Inactivating
mutations
15 No No N/A
CTNNB1 3Regulates the WNT
signalling pathway
Activating
mutations
1No No No
DCC 18 Netrin receptor; regulates
apoptosis, is deleted but not
mutated in colorectal cancer,
and its role in primary cancer
is still unclear
Deletion or LOH 9 (mutation);
70(LOH)
No Possible No
FAM123B XInvolved in the WNT
signalling pathway
Inactivating
mutations
10 No No No
FBXW7 4Regulates proteasome-
mediated protein
degradation
Inactivating
mutations
20 No No No
PTEN 10 Regulates the PI3K–AKT
pathway
Inactivating
mutations and
loss of protein
(assessed by
immunohisto-
chemistry)
10 (mutation);
30(loss of
expression)
Possible No Cowden
syndrome‡
RET 10 Regulates the GDNF
signalling pathway
Inactivating
mutations and
aberrant DNA
methylation
7 (mutation);
60
(methylation)
No No No
SMAD4 18 Regulates the TGFβ and BMP
pathways
Inactivating
mutations and
deletion
25 Possible Possible Juvenile
polypsis
TGFBR2 3Regulates the TGFβ pathway Inactivating
mutations
20 No No No
TP53 17 Regulates the expression
of target genes involved in
cell cycle progression, DNA
repair and apoptosis
Inactivating
mutations
50 Possible Possible Li–Fraumeni
syndrome
Proto-oncogenes
BRAF 7Involved in the MAPK
signalling pathway
V600E-activating
mutation
8–28 Probable Probable Lynch
syndrome
ERBB2 17 Involved in the EGF–MAPK
signalling pathway
Amplification 35 No No No
GNAS 20 Regulates Gprotein
signalling
Mutation 20 No No No
IGF2 11 Regulates the IGF signalling
pathway
Copy number
gain and loss of
imprinting
7 (mutation);
10
(methylation)
No No No
KRAS 12 Regulates intracellular
signalling via the MAPK
pathway
Activating
mutations in
codons 12 or
13 but rarely in
codons 61, 117
and 146
40 Yes Possible N/A
MYC 8Regulates proliferation
anddifferentiation
Amplification 2 (mutation);
10(CNV gain)
No No No
NRAS 1Regulates the MAPK
pathway
Mutation in
codons 12 or 13
2Yes No No
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although the mutations seem to cluster in epistati-
cally related groups (for example, genes involved in
a certain signalling pathway)58–60. The most com-
mon mutations in colorectal cancer include those in
APC, catenin-β1 (CTNNB1), KRAS, BRAF, SMAD4,
transforming growthfactor-β receptor2 (TGFBR2),
TP53, phosphatidylinositol-4,5-bisphosphate
3-kinase catalytic subunit-α (PIK3CA), AT-rich inter-
active domain1A (ARID1A), SRY (sex- determining
regionY) box 9 (SOX9), family with sequence
similarity123B (FAM123B; also known as AMER1)
and ERBB2, which promote tumorigenesis by perturb-
ing the function of key signalling pathways, includ-
ing the WNT–β-catenin, epidermal growth factor
(EGF)–mitogen-activated protein kinase (MAPK),
phosphatidylinositol 3-kinase (PI3K) and TGFβ sig-
nalling pathways, or by affecting genes that regulate
the c entral behaviours of cells, such as DNA repair
and proliferation61,62 (TABLE1). Colorectal cancer is
frequently initiated by mutations that affect the WNT
Table 1 (Cont.) | Common genetic and epigenetic alterations in colorectal cancer*
Gene or
biomarker
Chromo some Function Molecular
lesion
Frequency
(%)
Predictive? Prognostic? Diagnostic?
Proto-oncogenes (Cont.)
PIK3CA 3Regulates the PI3K–AKT
pathway
Mutations in the
kinase (exon20)
and helical
(exon9) domains
20 Probable Possible No
RSPO2 and
RSPO3
8 and 6,
respectively
Ligands for LGR family
receptors, and activate the
WNT signalling pathway
Gene fusion and
translocation
10 No No No
SOX9 17 Regulates apoptosis Copy number
gain
9 (mutation);
<5(CNV gain)
No No No
TCF7L2 10 Regulates the WNT
signalling pathway
Gene fusion and
translocation
10 No No No
Other molecular alterations
Chromosome
instability
N/A N/A Aneuploidy 70 Probable Probable No
CpG island
methylator
phenotype
N/A N/A Methylation of
>40% of loci
from a selected
panel of markers
15 Probable Probable No
Microsatellite
instability
N/A N/A Unstable
microsatellite
repeats in the
consensus panel
15 Probable Yes Lynch
syndrome
Mismatch-repair
genes
N/A Regulate DNA mismatch
repair
Loss of protein
(as assessed by
immunohisto-
chemistry),
methylation
and inactivating
mutations
1–15 Possible Probable Lynch
syndrome
SEPT9 17 N/A Methylation >90 No No Serum-based
assay for
cancer
detection
VIM, NDRG4
and BMP3
10, 16 and 4,
respectively
N/A Methylation 75 No No Stool-based
test for early
detection
18qLOH 18 N/A Deletion of the
long arm of
chromosome 18
50 Probable Probable No
APC, adenomatous polyposis coli; ARID1A, AT-rich interactive domain 1A; BMP, bone morphogenetic protein; CNV, copy number variation; CTNNB1, catenin-β1;
DCC, DCC netrin 1 receptor; EGF, epidermal growth factor; FAM123B, family with sequence similarity 123B; FBXW7, F-box and WD repeat domain-containing 7,
E3ubiquitin protein ligase; GDNF, glial cell-derived neurotrophic factor; GNAS, guanine nucleotide-binding protein, α-stimulating complex locus; IGF, insulin-like
growth factor; LGR, leucine-rich repeat-containing Gprotein-coupled receptor; LOH, loss of heterozygosity; MAPK, mitogen-activated protein kinase; N/A, not
applicable; NDRG4, NDRG family member 4; PI3K, phosphatidylinositol 3-kinase; PIK3CA, phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit-α;
PTEN,phosphatase and tensin homologue; RSPO, R-spondin; SEPT9, septin 9; SMAD4, SMAD family member 4; SOX9, SRY (sex-determining regionY) box 9;
TCF7L2, transcription factor7-like2; TGFβ, transforming growth factor-β; TGFBR2, TGFβ receptor 2; VIM, vimentin. *Includes alterations in gene expression,
genedeletions and amplifications, somatic mutations and aberrant promoter methylation. ‡Germline mutation, not somatic.
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signalling pathway, and the ensuing neoplastic cells
then progress upon deregulation of other signalling
pathways, including the RAS–RAF–MAPK, TGFβ, and
PI3K–AKTpathways60,63.
In addition to gene mutations, epigenetic altera-
tions commonly occur in polyps and colorectal cancers
and seem to cooperate with gene mutations to drive
the polyp to cancer progression58,64,65. DNA methyla-
tion affects CpG-rich regions (CpG islands), which are
often located in the 5ʹ region of genes and can result
in transcriptional silencing through effects on tran-
scription factor binding and changes in the chromatin
structure66. Modifications in DNA methylation related
to the develop ment of cancer (in general) include two
fundamental changes: hypermethylation of CpG islands
in gene promoters, which can silence tumour suppres-
sor genes, and hypomethylation of repetitive genetic
elements, which can lead to genomic instability or onco-
gene activation67. Hypermethylation, such as of the sep-
tin 9 (SEPT9) gene promoter, is also used for screening
p urposes (seebelow).
Importantly, the frequencies of many of these
molecular features vary depending on the location of
the tumour in the gut (from the ascending colon to the
rectum)68,69. Some studies support a gradual gradi ent
in change in frequency of the molecular alterations,
whereas others suggest a more abrupt dichotomy.
This has led to the traditional dichotomy of ‘proxi-
mal’ and ‘distal’ colorectal cancer versus adoption of
a continuum model. Both models support the notion
that the tumour microenvironment (the gut micro-
biota and the inflammatory state of adjacent t issue)
modulates the way these mutations affect cancer
formation and disease progression. Thus, our cur-
rent understanding of the patho genesis of colorectal
c ancer is that the disease results from the accumulation
of mutations in genes that then drive the formation of
the tumour in the context of tumour-promoting fac-
tors derived from the adjacent tissue. This paradigm
formed the basis for recent recommendation to deter-
mine the insitu immune cell infiltrate of the tumour
as a prognostic marker alongside its (standard) TNM
stage70. Inclose conjunction with these data, recent
research has focused on the role of the gut micro biota
in colorectal carcinogenesis. Indeed, studies have
shown the enriched presence of fusobacteria71, par-
ticularly in cancers with CIMP status72, which might
be inversely related to the CD3+ Tcells in colorectal
cancers73. Together, these data form a basis for fur-
ther research into the role of the colon microbiota and
coloncarcinogenesis.
Diagnosis, screening and prevention
Diagnosis
A diagnosis of colorectal cancer either results from an
assessment of a patient presenting with symptoms or
as a result of screening. The disease can be associated
with a range of symptoms, including blood in stools,
change in bowel habits and abdominal pain. Other
symptoms include fatigue, anaemia-related symptoms,
such as pale appearance and shortness of breath, and
weight loss. The predictive value of these symptoms for
the presence of colorectal cancer in an elderly patient
is limited, but they do warrant further clinical evalu-
ation. With the widespread introduction of popula-
tion screening for colorectal cancer, many individuals
are diagnosed at the preclinical stage. In symptomatic
patients, colonoscopy is the preferred method of
investigation, but other endoscopic methods are also
available or being developed (BOX2). For population
screening, a range of other methods can be used for
primary assessment, followed by colonoscopy in case
of a positivetest.
Box 2 | Endoscopic techniques for the diagnosis of colorectal cancer
High-definition white-light endoscopy
• Current standard for colonoscopy, combining high‑definition video endoscopes with
high‑resolution videoscreens
• Provides detailed images of the gastrointestinal mucosa
• Advantage of routine endoscopy; disadvantage that it provides no specific contrast
for the detection of neoplastic lesions
Chromoendoscopy
• The use of a dye spray during gastrointestinal endoscopy to improve visualization
• Improves the detection of neoplastic lesions
• Time‑consuming to spray the complete colon
• A new technique with dye incorporated into colon preparation is under investigation
Magnification endoscopy
• Endoscope with zoom‑lens in the tip, which enables 6–150‑fold enlargement of
themucosa
• Can characterize and determine the extension of neoplastic lesions
• Not suitable for screening of the complete colon
• Can be combined with other methods
Narrow-band imaging
• A technique that can also be built into white‑light endoscopes
• Filters light to two bands, with a wavelength of 415 nm (blue) and 540 nm (green),
respectively
• Longer wavelength light is less scattered and, therefore, penetrates deeper into
themucosa
• Blue light enhances superficial capillaries, whereas green light shows deeper,
subepithelial vessels
• Can characterize and determine the extension of neoplastic lesions
• Does not increase neoplasia detection rates
Intelligent colour enhancement (FICE; Fujinon) and iScan (Pentax) imaging
• Similar techniques as narrow‑band imaging, but with no filtering of the outgoing light
• Instead, processes the reflected light
Autofluorescence endoscopy
• A technique that can also be built into white‑light endoscopes
• Based on the principle that illumination with a specific blue wavelength light can lead
to excitation of tissue, which then emits light with a longer wavelength
• Wavelength of the emitted light is longer for neoplastic tissue
• Can be used to search for neoplastic lesions
Endomicroscopy
• A technique of extreme magnification endoscopy
• Enables invivo visualization of individual glands and cellular structures
• Can evaluate neoplastic lesions
• Not suitable for scanning larger mucosal surfaces
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Colonoscopy. Colonoscopy is the gold standard for the
diagnosis of colorectal cancer. It has a high diagnostic
accuracy and can assess the location of the tumour.
Importantly, the technique can enable simultaneous
biopsy sampling and, hence, histological confirma-
tion of the diagnosis and material for molecular profil-
ing. Colonoscopy is also the only screening technique
that provides both a diagnostic and therapeutic effect.
Removal of adenomas using endoscopic polypectomy
can reduce cancer incidence and mortality9,74–77. Indeed,
the efficacy of colonoscopy for the reduction of colo-
rectal cancer incidence and mortality was well dem-
onstrated by the US National Polyp Study76,78. Recent
20-year follow-up data from this study showed a reduc-
tion in colorectal cancer-related mortality of 53%76,
which is an encouraging result that has been echoed
by a more-recent study79. The quality of colonoscopy is
a determining factor in the diagnostic yield of cancer
and adenoma, which is the most certain way of avoid-
ing interval cancers (that is, a tumour arising in between
screening visits)9,75,80,81.
The image quality of colonoscopy has markedly
improved over the past 20years, from original fibre-
optic to videochip endoscopes. Videochip endoscopes
were further improved over the years, leading to higher
resolution and wider angle of view. The current standard
combines high-power endoscopes with high- resolution
videoscreens to yield high-definition white-light
endo scopy (hWLE). Although various technologies
for further image enhancement in colonoscopy have
been introduced over the past decade, none of them
have beenshown to improve the diagnosis of polyps
and colorectal cancer compared withhWLE82. Only
chromo endoscopy (BOX2) has proven to be superior
to hWLE in the identifi cation of adenomas83. Narrow-
band imaging, imaging with the Fujinon Intelligent
Colour Enhancement system (Fujinon Corporation,
Saitama, Japan) and autofluorescence endoscopy
are not advan tageous over hWLE in the detection of
adeno mas or carci nomas82. The Third Eye Retroscope®
device (Avantis Medical Systems, California, USA) was
designed to address the fact that lesions behind mucosal
folds in the gut are often missed. This endoscope pro-
vides a simultaneous retrograde view of the colon that
complements the forward view of a standard colono-
scope. Several pilot studies have indicated that it might
be useful84–86, but more data are needed. The invasive
nature of colonoscopy poses a burden to screenees and
patients, which might affect participation in screening
programmes. In recent years, several alternative diag-
nostic methods have been i ntroduced, such as capsule
endoscopy and biomarker tests.
Capsule endoscopy. Capsule endoscopy uses a wireless
capsule device that is swallowed by the screenee and
enables examination of almost the entire gastro intestinal
tract without the use of conventional endo scopy87–90.
Capsule endoscopy is useful in diagnosing adenomas
and colorectal cancer. The first-generation capsule
endoscopy was found to be able to detect p olyps >6 mm
in size with a sensitivity of approximately 60% and
specificity of >80%87. Cancer detection was achieved in
74% of patients with colorectal cancer87. With the devel-
opment of the second-generation capsule endoscopy
for the colon (PillCam® Colon2 (Given Imaging Ltd,
Yokne’am Illit, Israel)), the frame speed was increased
from a fixed speed of four pictures per second to a vari-
able 4–35 pictures per second depending on capsule
movement. The angle of view was widened from 156°
to 172° on both ends of the capsule, providing a 344°
view. A large trial in the United States and Israel assessed
the accuracy of this new capsule to diagnose colorectal
neoplasia. With 884 patients included, sensitivity was
shown to be 88% and specificity 82% for the detection
of adenomas >6 mm insize91.
The European Society for Gastrointestinal Endoscopy
guideline for colon capsule endoscopy recommends cap-
sule endoscopy as a feasible and safe tool for the visual-
ization of the colonic mucosa in patients who have
undergone no or incomplete colonoscopies90. This rec-
ommendation was then also incorporated in the Asia–
Pacific guidelines on colorectal cancer screening92. The
indications for capsule endoscopy are at this moment
limited to patients who refuse conventional colono-
scopy and to those in whom a complete colonoscopy is
not possible for anatomical reasons. The presence of a
s tenosis is a contraindication for capsule endoscopy as
it could lead to capsule retention.
CT colonography. CT colonography uses low-dose CT
scanning to obtain an interior view of the colon. The
technique is well established as a diagnostic modality
for colorectal cancer93. In a systematic review and meta-
analysis that included >11,000 people from 49centres,
CT colonography was shown to have a sensitivity of 96%
for the detection of colorectal cancer94. This performance
is similar to that of conventional colono scopy. A recent
study reported similar performance of CT colonography
and capsule endoscopy in patients with previous incom-
plete colonoscopy95. A large trial in 411 patients with
obstructive cancers showed excellent performance of CT
colonography for the evaluation of proximal synchro-
nous lesions96. An observational study based on data
from England of 2,731 people with a positive guaiac
f aecal occult blood test (gFOBT, see below) showed that
the detection rate of advanced neoplasia was signifi-
cantly lower for subsequent CT colonography than for
subsequent colonoscopy97. Furthermore, the detection
and accuracy rates for advanced neo plasia were bette r
in high-volume centres. These findings underline the
need for adequate quality assurance s imilar to measures
implemented for colonoscopy screening.
CT colonography requires full bowel preparation
(that is, clearance of the bowel), air inflation and a
change in position of the patients during the examina-
tion. The discomfort to the screenee undergoing CT
colonography is similar to colonoscopy in experienced
hands, particularly because of the need for substantial
bowel insufflation98, but it has the advantage of obviat-
ing the use of sedation and can be used as part of the
s taging procedure in a confirmed case of colorectal can-
cer. However, CT colonography has low sensitivity for
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small (6–9 mm) and flat lesions99. The technique is asso-
ciated with high colonoscopy referral rates (up to 30%)
and high rates of extra-colonic findings in non-cancer
cases, which translate to unnecessary investigations and
increased anxiety for individuals100,101. The costs of CT
colonography and the need for further investigation in
a subset of screenees limit the usefulness of this method
for population screening in mostcountries.
CT colonography has been recommended as one of
the options for colorectal cancer screening in guidelines
in the United States and Europe102,103. In many countries,
CT colonography has replaced double-contrast barium
enema examination (the conventional X-ray-based
imaging modality for the colon) and is increasingly
being used as an alternative to conventional colonos-
copy. However, CT colonography has not readily been
accepted in Europe because of radiation exposure, costs,
burden to patients and high colonoscopy referral rates.
In the Asia–Pacific region, CT colonography is not rec-
ommended for colorectal cancer screening, except in
those for whom total colonoscopy is not possible92.
Biomarkers of colorectal cancer. Molecular detection
of colorectal cancer offers a non-invasive test that is
appealing to patients and clinicians as samples of mul-
tiple patients can be analysed in batch. The ideal molec-
ular marker should be highly discriminating between
cancer and advanced adenomas from other lesions, be
continuously released into the bowel lumen or circula-
tion, and disappear or reduce after the lesion is removed
or treated. Indeed, assays using proteins, RNA and DNA
in the blood, stool and urine have been developed but
with varying degrees of success (TABLE1). Stool tests are
based on the fact that early cancers as well as advanced
pre-malignant lesions can bleed and shed cells into
the bowel lumen, which can be detected. Blood tests
obviate the handling of stool and urine and can be per-
formed alongside routine checking of blood sugar and
c holesterol in the elderly population.
SEPT9 belongs to a class of GTPases, and hyper-
methylation of its promoter region is associated with
colorectal cancer; aberrant methylation of SEPT9 at the
tissue level discriminates colorectal neoplasia from nor-
mal mucosa. Early case–control studies from referral
centres showed that SEPT9 methylation testing yielded
a moderate sensitivity of 50–70% for colorectal cancer,
with a specificity of 85–90%104. However, a more-recent
larger scale study in the population with average risk
of developing the disease suggested a colorectal cancer
detection rate of <50% when using SEPT9 methyl ation
testing105. The reported detection of advanced colonic
adenoma by SEPT9 methylation status is only approxi-
mately 10%. As such, SEPT9 assays are out performed
by current quantitative faecal immunochemical
tests(FITs).
Mutations of APC and KRAS have been tested in
DNA shed by epithelial cells and isolated from stool
samples. The first-generation faecal DNA tests only gave
satisfactory results with fair sensitivity for the detection
of colorectal cancer but low sensitivity for thedetec-
tionof advanced colonic adenomas106. Since then, several
technological improvements have been made, includ-
ing the use of a stabilizing buffer, the addition of other
more-discriminating markers (KRAS mutations, aber-
rant NDRG family member4 (NDRG4), bone morpho-
genetic protein3 (BMP3) methylation and the presence
of β-actin), the use of more-sensitive analytical methods
and the optimization of the determining algorithm — all
of which have improved the accuracy of the assay (see
further description below)107. Other potentially useful
markers under investigation include circulating tumour
mRNA, microRNA and circulatingcytokeratins108.
Screening and prevention
Colorectal cancer is more suitable for population
screening than any other malignancy owing to a com-
bination of factors1. First, the incidence of the disease
is high, and outcome for a significant proportion of
affected patients is poor despite intense, burdensome
and often very costly treatments109. Colorectal cancer
also has a long preclinical stage. For instance, 7,151
Dutch men 55–75years of age were newly diagnosed
with colorectal cancer in 2012 (see the Dutch Cancer
Registry: www.cijfersoverkanker.nl), which corresponds
to approximately 0.2% of the 3.5million people in that
age group. Such an incidence is in line with similar
annual incidences in other western European c ountries.
However, colonoscopy screening studies generally tend
to find prevalent colorectal cancer in 0.5–0.9% of the
participants in the same age group53,62,63. Although
an increased willingness of symptomatic screenees
might confound this difference, these data indicate
that colorectal cancer on average progresses for several
years before becoming symptomatic. Furthermore,
colorectal cancer is preceded by colorectal adenoma.
Inindivid uals with sporadic (non-hereditary) disease,
the progression from adenoma to cancer takes at least
5–10years110. The long preclinical stage of the d isease
offers a large window of opportunity for screening.
Second, colorectal cancer is also suitable for screen-
ing because adenomas and early cancers are detectable
and treatable entities, which is in contrast to precursors
of other highly common cancers of the breast, prostate
andlung.
Last, both endoscopic removal of adenomas and
treatment of early-stage cancers have a profound
effect on colorectal cancer mortality. After a 20-year
follow-up of the US National Polyp Study cohort, colo-
rectal cancer- specific mortality was approximately 50%
lower among subjects who at baseline had undergone
endoscopic removal of adenomas than in an unscreened
control cohort76. Furthermore, the 5-year survival rates
for patients with early-stage cancer are approximately
90%, compared with 10% for patients diagnosed with
advanced-stage metastatic disease. Together, these fac-
tors form the background for various international
guidelines on colorectal cancer screening. Screening
in most countries aims to capture men and women
whoare 50–75years of age, although different age ranges
arebeing used in various programmes depending on the
available resources111. Adoption of lifestyle measures can
also substantially affect colorectal cancer incidence.
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Endoscopy. Given that imaging of the colon can
confirm a diagnosis or exclude colorectal neoplasia,
clinicians often favour these methods for screening
purposes. Colorectal adenomas and early-stage c ancers
can directly be visualized by endoscopy, CT colono-
graphy or capsule endoscopy76,88,94,101. A randomized
comparison between CT colonography and colono-
scopy for primary population screening has shown a
slightly higher uptake of CT colonography, counter-
balanced by a slightly lower sensitivity for advanced
neoplasia101. Capsule endoscopy screening might in the
near future provide an alternative visualization method
for primary screening88. Overall, colonoscopy has the
highest accuracy, is generally considered the gold
standard for screening and is associated with several
advantages (TABLE2). Recent large observational stud-
ies showed that screening colonoscopy reduced the
risk of colorectal cancer by approximately 80%, and
had a similar effect on related mortality112,113. This
preventive effect of colonoscopy strongly depends
on procedural quality, which can be measured in
terms of adenoma detection rate of the performing
endoscopist75. Other measures for procedural quality
include the level of bowel preparation, caecal intuba-
tion rates, complication rates, average sedative medi-
cation dose and patient burden scores9. In a study
from the United States, adenoma detection rates per
colonoscopist ranged from 7% in the lowest quintile
of detection to 50% in the highest quintile — a dif-
ference that is associated with an almost twofold risk
in interval cancer80. The correlation between risk of
post-colonoscopy cancer and adenoma detection rates
was also reported in a study from Poland75. Training
and quality-assurance m easures, and adherence to sur-
veillance guidelines also have an effect on the rate of
post-colonoscopycancers74,114.
Sigmoidoscopy, which images the rectum and sig-
moid colon and can include the descending colon,
has been shown in several randomized prospective
trials to reduce the incidence of colorectal cancer by
approximately 33% and reduce related mortality by
38–59%1,115–117. This effect was obtained by single sig-
moidoscopy screening, with further colonoscopy in
those with signs of advanced polyps — a finding that
formed the basis for the current roll-out of nation-
wide primary sigmoidoscopy screening in England.
The wide use of colonoscopy and sigmoidoscopy for
primary screening in various countries supports the
introduction of non-physician endoscopists who can
perform diagnostic endoscopy according to inter-
national standards118. Further studies are needed to
assess p erformance and cost efficacy119.
Population screening. Given the considerable rise in
treatment costs, colorectal cancer screening is a cost-
saving exercise in many countries120. Screening can
Table 2 | Key performance indicators for organized screening with different modalities
Test Advantages Disadvantages Refs
gFOBT • Cheap
• Low screenee burden
• Reasonable uptake
• Limited sensitivity for advanced neoplasia
• Need for short screening intervals
• No effect on the incidence of colorectal cancer
• Qualitative, not automated
• Multiple sampling
• Moderate positive predictive value
123,124,
225
FIT • Cheap
• Low screenee burden
• Quantitative, automated
• Single sample
• Sensitive for colorectal cancer
• Highest uptake
• Effect on incidence and mortality
• Limited sensitivity for advanced adenoma
• Moderate positive predictive value
• Repeated screening needed (interval can be
longer than for gFOBT)
• Temperature-dependent performance*
124,126,
127,131,
226
Sigmoidoscopy • Sensitive for distal advanced
neoplasia
• Long screening interval
• Effect on incidence and mortality
• Low uptake
• Expensive
• Moderately sensitive for proximal advanced
neoplasia
115–117,
227
Colonoscopy • Sensitive and specific
• Long screening interval
• Effect on incidence and mortality
• Low uptake
• Expensive
• Burdensome
• Associated with complications
75,76,80,
135,228
CT colonography • Sensitive and specific
• Long screening interval
• Likely effect on incidence and
mortality
• Low uptake
• Expensive
• Need for repeated lavage in case of advanced
neoplasia
• Radiation exposure
• Burdensome
93,94,
96–98,
101,103,
229
Multi-target
faecal DNA test
• Sensitive and specific • Uptake unknown
• Expensive
• Lack of prospective data
107,108
FIT, faecal immunochemical test; gFOBT, guaiac faecal occult blood test. *Less problematic with newer-generation tests.
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be carried out using a range of methods, both inva-
sive and non-invasive (TABLE2). Most programmes are
based on a single primary screening test, followed by
colonoscopy in those who test positive111. In other set-
tings, screenees are offered a choice between different
screening methods, which might increase or decrease
participation rates depending on the local setting121,122.
Population screening must consider more than
just test accuracy, but should take test uptake and
the demand on resources into account. Accordingly,
screening results must be reported in terms of identifi-
cation of subjects with advanced neoplasia per 1,000
invited and in numbers needed to scope. Avery accu-
rate test by definition has no effect on cancer incidence
and mortality in a population if not widely applied1,109.
Similarly, limitations in endoscopy capacity pre-
clude the use of colonoscopy for primary screening.
For these reasons, many countries prefer a two-step
approach in population screening, first using a non-
invasive screening test to select a subgroup of screenees
who are at high risk of cancer for subsequent colono-
scopy. Typically, a faecal occult blood test is this pri-
mary screen1, either using gFOBTs or FITs. FITs are
now more widely used than gFOBTs because of easier
handling, resulting on average in approximately 10%
higher uptake, higher sensitivity for advanced neo-
plasia and automated analy sis123,124. Indeed, quanti-
tative FITs offer the additional advantage that their
cut-off points can be adjusted to match colonoscopy
capa city125. For an optimal impact on the population
level, adequate quality assurance is needed over the
full range of the screening programme, as is organized
active call–recallscreening1.
The effect of uptake on the yield of screening
was shown by a randomized study comparing pri-
mary colonoscopy and FIT screening in Spain126. The
c ancer detection rate was similar in both groups, but
a consider able proportion of cancers in the colono-
scopy group were actually detected by primaryFIT
screening after screenees first refused primary
colono scopy. Similarly, in a range of screening trials
in the Rotterdam area, the highest detection rate was
observed with repeated FIT screening1,127. This detec-
tion rate can be further increased with the use of two
samples per screening round, especially in the first
screening round128, although this approach is less cost
effective than screening with one sample129. gFOBT
screening r outinely makes use of a 1–2-year interval,
and the higher accuracy of FIT screening can allow for
extension of the screening interval to 3years130.
The performance of the aforementioned multi-
target faecal DNA test plus FIT was compared with
FITs alone for the detection of colorectal neoplasia107.
All participants in the study underwent each of the
‘experimental’ screening methods and a confirmatory
colonoscopy. The combined tests identified 60 out of
65 patients(92%) with colorectal cancer and 321 out
of 757 patients (42%) with advanced adenomas; FITs
alone detected 48 patients with colorectal cancer (74%;
P = 0.002) and 180 patients with advanced adenomas
(24%; P < 0.001)107. These results provide evidence
for the accuracy of the DNA test in asymptomatic
average- risk individuals, and led to US FDA approval
of the multi-target f aecal DNA test plus FIT. However,
thepositive predictive value of the multi-target faecal
DNA test was low (24%) for a non-invasive test, and
theDNA testplus FIT yielded a 16.1% positivity rate
versus 7% for FIT alone, thus necessitating 2.3-fold
more colonoscopies in the DNA test plus FIT arm.
Ifboth tests were compared at the same positivity
rate — a crucial determinant in c ountries with limited
colono scopy resources — the actual diagnostic yield and
positive predictive value could have been approximated.
This assumption is supported by previous studies that
reported a similar n umber needed to screen to detect
advanced neo plasia131. Finally, study design did not
include a component to examine uptake of either test.
For these reasons, further studies are needed to p osition
the DNA test as a population-screeningmethod.
Surveillance after resection
Patients who have adenomatous polyps or colo rectal
cancer continue to be at risk for new neoplastic lesions
after these have initially been removed — either
because of biological or environmental factors, or
both132. These patients could benefit from surveil-
lance to detect and remove new lesions. Most evidence
supporting this hypothesis is based on surveillance
studies that have documented higher rates of tubu-
lar adenomas >10 mm in size, adenomas with villous
histology, high-grade dysplasia or cancer in patients
with neoplasia at the baseline colonoscopy examina-
tion; the risk of developing subsequent tumours also
depends on the size and histology of polyps at the index
examination132–134. Furthermore, there is a relationship
between the index lesion and subsequent risk of death
from colorectal cancer135. Together, this body of data
provides a strong justification for surveillance, but does
not prove with certainty that surveillance will actually
prevent recurrent cancer or reduce mortality.
Guidelines for surveillance in patients without
hereditary syndromes vary in the United States and
Europe133,136,137. The underlying premise of all such rec-
ommendations is that the baseline examination must
be complete (including the caecum), with adequate
bowel preparation, and that any detected lesions are
removed completely. If the completeness of the resec-
tion or quality of the examination comes into question,
early re-examination is recommended. The guidelines
stratify risk based on the findings of the index exami-
nation (BOX3). The US guidelines endorse a 10-year
interval if the baseline examination is negative or if the
patient only has hyperplastic polyps in the rectum or
sigmoid colon. New evidence adds further support for
this recommendation79,138. Interval faecal blood test-
ing is generally not recommended, owing to a lack of
e vidence of benefit133,136.
Several longitudinal studies of patients after ade-
noma removal have provided some guidance for the
optimal intervals for surveillance examinations132,134.
Surveillance intervals are based on the findings at the
last colonoscopy (BOX3). If the patient has an adenoma
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with high-risk features at baseline but no polyp or an
adenoma with low-risk features at surveillance, the
next examination is recommended at 5years. If the
patient has an adenoma with low-risk features at base-
line and at surveillance, the next examination interval
is recommended at 5years; if there is no polyp at sur-
veillance, the next examination interval is at 10years.
Finally, if a high-risk adenoma is found at surveillance,
the next examination is recommended at 3years. These
recommendations are designed to reduce the frequency
of surveillance for many individuals with low-risk
lesions and are based on findings using high-quality
colono scopy. Complete examinations with good bowel
prepar ation9 are required, but the role of other mitigat-
ing factors during surveillance such as lifestyle, sex and
race are unknown. Surveillance should be discontinued
when the risks of performing the bowel prepar ation
and/or colonoscopy could outweigh any potential
bene fit. These factors should also be considered in
elderly patients with co-morbid conditions that might
limit life expectancy, diminish any potential benefit of
polyp removal and increase the risk of co mplications
during the colonoscopyprocedure139,140.
How to conduct surveillance of patients with
s errated lesions is under debate. Understanding the nat-
ural history of these lesions requires accurate histologi-
cal definition, endoscopic detection and longitudinal
follow-up141. Furthermore, inter-observer variability in
histological interpretation, wide variation in detection
rates and virtually no longitudinal follow-up study of
these patients have hindered surveillance assessment142.
Nevertheless, some evidence suggests that this pathway
accounts for >20% of colorectal cancers, and patients
may be at risk for recurrent disease and, therefore,
require surveillance after resection. Further studies have
to substantiate the risk for recurrent polyps and define
optimal surveillance schedules.
In addition to endoscopic surveillance after cancer
resection, follow-up surveillance by measuring carcino-
embryonic antigen (CEA) levels in the plasma and/or
CT imaging might detect curatively treatable meta-
static recurrence143. There have been concerns about
the cost, benefit and number needed to test to achieve
a survival benefit. A randomized study found that CEA
testing resulted in 6.7% of patients receiving treatment
with curative intent and CT resulted in 8% receiving
treatment, which was significantly more than a group
receiving minimum follow-up care that involved only
targeted diagnostic assessment if symptomatic144. The
actual survival benefit was probably small. The cost-
effectiveness is also uncertain, but CEA testing is likely
to be more cost effective than CT, depending on the cost
in different countries.
Management
Although the molecular drivers of colorectal cancer
have been described, where in the gut a tumour occurs
has implications for treatment. That is, colon cancer and
rectal cancer are two distinct cancers requiring different
approaches, also depending on their stage. Cancer reg-
istries from different countries show huge differences in
outcomes after treatment for colorectal c ancer, although
a trend for improvement is emerging145. Fortunately,
increasing attention is being paid to quality assurance
in cancer care146. Indeed, unravelling the effects of
treatment on outcome is of utmost importance and, for
this, population-based registries and audits are used to
c ritically assess practice.
Surgery
Surgery is the mainstay curative treatment for patients
with non-metastasized colorectal cancer. However,
outcome is strongly related to the quality of sur-
gery147,148, the quality of preoperative staging and treat-
ment selection. The dissection should ideally follow
theembryological anatomical planes to ensure thatthe
tumour and its principle zone of lymphatic spread
are removed. Special attention should be given to the
circum ferential surgical resection margins148,149 (FIG.4).
In more-advanced cases of rectal cancer, neoadjuvant
treatment (for example, preoperative chemotherapy
for T4 colon cancer, and chemoradiotherapy or radio-
therapy for locally advanced cancer) can reduce tumour
load and even tumour stage, and might be necessary to
Box 3 | Surveillance guidelines
Colorectal cancer
• Patients with colorectal cancer should have intensive follow‑up care
• If a complete colonoscopy was not possible before surgical resection, colonoscopy
should be offered within 3–6months to detect synchronous lesions
• If a complete colonoscopy was performed at baseline, patients with colorectal cancer
should have colonoscopy at 1year; if negative, every 3–5years thereafter
High-risk adenoma
• High‑risk features include adenomas with high‑grade dysplasia, villous histology,
tubular adenoma >10 mm in size, serrated lesions >10 mm in size, serrated lesions
with dysplasia or ≥3 adenomas
• The risk of advanced neoplasia during surveillance is 15–20%, which is approximately
2–3‑fold higher than individuals with 1–2 small (<10 mm) tubular adenomas and
5–6‑fold higher than individuals with no polyps at baseline colonoscopy133
• The US Multi‑Society Task Force on Colorectal Cancer (USMSTF)133 and European
Society of Gastrointestinal Endoscopy (ESGE)136 guidelines recommend a 3‑year
interval for surveillance
• The UK guidelines define highest‑risk features as >5 small adenomas or >3 adenomas,
in which at least one is >10 mm in size, and recommends annual surveillance137 based
on data indicating a high likelihood of finding additional high‑risk adenomas at
1year221
• The UK guidelines define intermediate‑risk features as 3–4 small (<10 mm) adenomas
or ≥1 large (>10 mm) adenomas, irrespective of histology, and suggest a 3‑year
screening interval
Low-risk adenoma
• Individuals with 1–2 tubular adenomas <10 mm in size represent a low‑risk group
• A statistically insignificant increase in risk, relative to patients with no polyps at
baseline colonoscopy, are attributed to these patients
• The UK guidelines recommend no specific follow‑up137; the ESGE guidelines
recommend follow‑up at 10years136; the USMSTF guidelines recommend surveillance
at 5–10years, with evidence supporting the 10‑year interval if the index examination
preparation was adequate133
• Serrated lesions <10 mm in size with no dysplasia might also represent a low‑risk
lesion, but evidence is weak; the USMSTF recommends a 5‑year interval for
surveillance and the ESGE recommends a 10‑year interval
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optimize the chances for a successful resection146,148,150.
Thus, a multidisciplinary approach before beginning
treatment, based on adequate staging information,
ismandatory147,149,151,152.
Preoperative assessment. When considering a patient
for surgery, several factors such as their age, fitness,
the perioperative management plan, tumour s taging,
type of surgery (including resection planes and recon-
struction) and quality assurance are important. In
terms of age, elderly patients with colorectal cancer
have lower overall survival rates than their younger
counterparts145. Indeed, postoperative mortality rates
increase in elderly patients in the immediate post-
operative period (that is, the first 30days) and can
double in the first 6–12 postoperative months153–156.
However, ‘elderly patients’ as a group are hetero-
geneous, with varying co-morbidities, degrees of
fitness for surgery and risks for postoperative compli-
cations. Accordingly, age alone should not be a reason
not tooperate.
Before patients undergo surgery for colorectal
c ancer, it is important to be informed about the whole
colon to rule out synchronous cancers, which occur in
approximately 4% of patients157. If preoperative endo-
scopy was incomplete owing to tumour obstruction,
visualization of the colon should either be completed
before surgery by CT colonography or endoscopy
should be performed in the 3months following surgi-
cal resection96,157. Active search for distant metastases in
the lungs and liver by means of a chest and abdominal
CT is also recommended before surgery151. CEA levels
are preferably obtained before colorectal cancer surgery
to provide a baseline value for postoperative surveil-
lance. Genetic counselling is advised in young patients
with a positive family history of colorectal cancer. Fast-
track protocols and laparoscopy should be considered
to minimize the surgical trauma. In those with obstruc-
tive colorectal disease, abdominal CT imaging can also
assess for T4. In patients with rectal cancer, preoperative
MRI of the pelvis is further recommended for planning
purposes, as well as to distinguish the tumour in relation
to the mesorectal fascia, and to assess Tstage158. This
information is necessary to select patients with T3c, T3d
and T4 tumours for preoperative c hemoradiotherapy
orradiotherapy.
Colon surgery. Laparoscopic resection of colorectal
cancer (FIG. 5) has been shown to be as safe as open
surgery159–161. As with any surgical procedure, the team
needs to be skilled in laparoscopic colorectal surgery
and adequately select patients. Contraindications for
laparoscopic approach are obesity, previous abdominal
surgeries and advanced-stage disease147,148,160. If, dur-
ing the laparoscopic procedure, conversion to open
surgery is necessary, the earlier this is done the better
theoutcomes.
In colon surgery, anatomical planes of the meso-
colon with the parietal cavity wall and retroperitoneum
should be followed to avoid damage of the ureters, duo-
denum, pancreas and spleen. Moreover, the mesenteric
margins are planned accurately, ensuring proficient
Hepatic flexure Splenic flexure
Transversum
Ascending
colon Descending
colon
Caecum
Rectum
Out
Sphincter ani
Muscle leviator ani
Dissection planes
Fascia anterior
Mesocolon
Serosa
Mucosa Ascending
colon
Retroperitoneum
Ureter
a b
White line
of Toldt
(b)
Sigmoid
colon
Mesocolon
White line
of Toldt
Nature Reviews | Disease Primers
Parietal
peritoneum
Visceral
peritoneum
Parietal
fascia
Visceral
fascia
Figure 4 | Surgical planes for right colon surgery. a | The mesocolon harbours the main blood vessels and draining
lymph nodes; surgical planning involves considering the large blood vessels and the resection lines. For the caecum and
the ascending colon (before the hepatic flexure), the main vessels are the ileocolic and right colic artery. The transverse
colon begins at the hepatic flexure and ends at the splenic flexure; important vessels to consider in this region are the
middle colic artery (via the superior mesenteric artery) arcading on the left side, with branches of the left colic artery
(inferior mesenteric artery). The descending colon ‘bends’ at the sigmoid colon (at the left iliac crest) before continuing to
the rectum. b | In the paracolic grooves, the parietal peritoneum is attached to the lateral border of the visceral
peritoneum that overlies the colon and forms the surgical planes referred to as the White line of Toldt, which gives access
to the avascular plane above the fascia of Gerota — the fascia on top of the retroperitoneum covering the kidney and
ureter — without interfering with the perirenal space or ureters.
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vascularization of the remnant bowel loops for the
anasto mosis. Atension-free and torsion-free anasto-
mosis must be created to avoid the feared complication
of an anastomotic leakage.
Some patients might require perioperative place-
ment of a stoma, in which the faeces are diverted into a
bag on the outside of the body. Loop ileostomy or loop
colostomy (FIG.6), or permanent colostomies, are an
essential part of surgery for rectal and sigmoid c ancers,
either to protect the anastomosis or when the distal rec-
tum is resected. In cases of a rectal obstruction, aloop
colostomy is placed on the right (ascending) side; a
permanent stoma is placed in cases of an abdomino-
perineal excision (that is, removal of the anus, rectum
and part of the sigmoid colon along with the associated
lymph nodes). Each stoma has its advantages and dis-
advantages; there is no strong argument for superior-
ity of one over the other162. Complications of stomas
are numerous and cumbersome for the patient, and
include prolapse, retraction, dermatitis, leakage, para-
stomal hernia, obstruction and anastomotic leakage
after stoma closure.
In patients presenting with subtotal or total obstruc-
tion due to a left-sided (descending) tumour, temporary
preoperative stenting can be considered to reduce peri-
operative morbidity and risks of surgery, but the risk
of perforation must be considered147,148,163. Colostomy
versus stent for palliation could be considered in
patients presenting with obstruction and multiple
distantmetastases147,148,164.
Rectal surgery. There are several surgical approaches
for patients with rectal cancer, depending on the
tumour stage. Each technique aims for adequate onco-
logical treatment with complete tumour and local
node resection to minimize locoregional and distant
recurrence, and optimize disease-free and overall sur-
vival. In addition, sphincter preservation and avoid-
ance of a permanent stoma are important additional
goals of rectal cancer treatment. Accordingly, a care-
ful, balanced choice of treatment is needed for each
individualpatient.
For early-stage rectal cancer, advances in minimally
invasive techniques have reduced the number of open
rectal resections and have improved functional out-
come dramatically. Transanal endoscopic micro surgery
(TEM) is just such a minimally invasive technique for
local tumour excision of well-differentiated T1N0
tumours165–167. TEM is associated with better functional
outcomes and is performed through the anus (and,
therefore, does not leave an abdominal scar or require
a stoma), but has the trade-off of higher local recur-
rences. Thus, TEM is not recommended for tumours
that are unlikely to be completely resected, as well as
for poorly differentiated tumours given their high risk
of local recurrence. The technical complexity of TEM
and the high costs of the apparatus led to the introduc-
tion of new transanal techniques, in particular trans-
anal minimally invasive surgery. This technique makes
use of a disposable multichannel port that is positioned
transanally and provides access for conventional
laparoscopicequipment168.
Total mesorectal excision (TME) is the gold- standard
surgical technique for rectal tumours staged T1, T2 and
favourable T3 (that is, T3 with negative nodal status
(T3N0M0) and excluding low-seated rectal cancers, and
T3c and T3d disease). In patients with the unfavour-
able rectal tumours, TME surgery is only recommended
after neoadjuvant therapy to reduce the risk of local
recurrences. For tumour resection, the anatomical plane
Nature Reviews | Disease Primers
ab
1
4
3
X
2
5
3
4
2
1
X
Figure 5 | Laparoscopic surgery for colorectal cancer. a | A sigmoidectomy can be performed using three to six
trocars. The laparoscopic exploration via the supraumbilical trocar (2) is a guide for the location of the other operating
trocars. X indicates the tumour location. (1) A 5 mm trocar in the left hypochondrium, for retracting the descending colon.
(2) The first trocar to be introduced is a 12 mm trocar through the umbilical port. (3) A 12 mm trocar is used as an optical
and operating port. (4) A 5 mm trocar is used for retracting tissue. (5) Carbon dioxide insufflation: pneumoperitoneum.
b|The number of trocar ports for right colectomy varies depending on the surgeon and operative difficulties. Trocar
positioning is also variable, but our standard for a tumour in the caecum (shown in insert; X) is to place: (1) a 12 mm trocar
in the left hypochondrium as an optical or operating port. (2) The umbilical port side can be extended to a small
laparotomy to extract the dissected colon and perform the extracorporeal anastomosis. (3) A 5 mm trocar is placed for
operating and retracting the tissue (ascending colon or caecum). (4) A 5 mm trocar is used to retract the hepatic flexure, to
expose the ileocolic and right colic vessels, and perform the division. In both images, the patient’s head is at the top, their
feet are at the bottom.
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is the mesorectal fascia and the circumferential resec-
tion margin is just outside of this fascia169–171 (FIG.7). The
intact mesorectum — the fatty envelope that surrounds
the rectal bowel wall — includes the draining lymph
nodes. Complete resection involves removal of the
bowel wall and these nodes. TME can be performed by
an open approach as well as laparoscopically; both have
similar rates of locoregional recurrence and disease-free
and overall survival160. Rectal cancer surgery in locally
advanced stages is associated with more blood loss;
longer operation duration; more concomitant organ
resections; and more postoperative complications, such
as anastomotic leakage, pelvic floor dysfunction, incon-
tinence and genitourinary problems. However, robotic
rectal resection may improve perioperative outcomes,
such as reduction of perioperative blood loss, and is
being explored172.
Local recurrences after rectal surgery can be mini-
mized using short-course radiotherapy173–175, although
long-term data (12-year follow-up) showed no effect
on overall survival for this approach176. The timing of
surgery after short-course radiotherapy is important.
Surgery after a longer waiting period is associated
with fewer complications than immediate surgery after
radiotherapy177. Importantly, neoadjuvant radiotherapy
(that is, before surgery) is associated with an increased
risk for low anterior syndrome (a complex of symp-
toms that include frequent and urgent stools, numerous
bowel movements over a few hours, stool incontinence
and sexual dysfunction)178.
Neoadjuvant radiotherapy (or chemoradiotherapy)
can be proposed for patients with unfavourable T3
(upper and mid T3c, T3d and low T3b) rectal tumours:
those that invade >5 mm into the meso rectal fat
and/or approach within 2 mm of the meso rectalf ascia
as visualized on MRI. T4 and lymph node-positive rec-
tal cancer need short-course fractionated radiotherapy
or chemoradiotherapy depending on the patient and
tumour characteristics179. After the primary radio-
therapy or chemoradiotherapy, restaging by means of
endoscopy and MRI is recommended for these patients.
TME surgery can be possible when the tumour has
been downsized sufficiently. In patients with advanced
and recurrent rectal cancer, surgery should aim for
complete resection and conventional surgical planes
may not be adhered to180. In some patients, a clinical
complete response can be achieved after chemoradia-
tion alone. This raises the question whether surgery
can be omitted in these patients. In the largest series
of patients treated non-surgically, highresponse rates
were reported181. Other series had lower response
rates182,183. Prospective research will be necessary for
this group of patients. Indeed, in 2015, the prospec-
tive International Watch & Wait Database (http://
www.iwwd.org) for rectal cancer was launched;
this i nitiative aims to assess whether non-surgical
approaches are valuable alternatives to surgery.
Finally, a prospective multicentre randomized
trial in Japan comparing TME alone versus TME with
dissec tion of lateral nodes was recently completed184.
Subcostal line
Anterosuperior
iliac spine
Pubic tubercle
Linea alba
Rectus abdominis
Umbilicus
1
2 3
4
End colostomy
Colon
Lumen
Bowel
wall
Skin
Mucosa
Loop colostomy
Produces faeces
Mesocolon
In Out
Lateral barrier of
the rectus muscle
acb
Nature Reviews | Disease Primers
Skin
Subcutaneous fat
Anterior
fascia
Muscle
Posterior
fascia
Peritoneum Abdominal
cavity
Figure 6 | Stoma surgery for colorectal cancer. A colostomy is a surgical procedure in which a stoma (from the Greek for
‘mouth’ or ’opening’) is formed by drawing the healthy end of the colon through an incision in the anterior abdominal wall
and suturing it into place. a | For stoma positioning (sites 1–4), the subcostal line, lateral border of the rectus abdominus
muscle, anterosuperior spine of the ilium, shape of the abdomen and abdominal creases (for example, when trousers
andbelt are worn, and while sitting) are considered. Ill-placed ostomies result in invalidating leakage and dermatitis.
Theposition of an end ileostomy or a loop ileostomy is preferable in the right hypochondria (site 1); a loop transversostomy
is preferred in the right upper quadrant (site 2) to preserve the upper and lower quadrants of the left-side (site 3 and site 4,
respectively) for a definitive end colostomy if necessary. b | In end stoma formation, the inside of the intestinal loop with
the mucosa is placed at the abdominal wall. End stomas provide only one lumen, commonly formed to stay. A well-placed
ostomy is about 2–3 cm above the skin, which ensures that the faeces are not in contact with the skin. c|In loop stoma
formation, two openings are sewn into the skin: afferent (in) and efferent (out). The afferent limb produces the stool
andthe efferent limb enables the passage of flatus from the distal portion of the bowel.
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In this study, approximately 10% of patients had
patho logical pelvic sidewall lymph nodes. Given that
preoperative radiotherapy on lateral nodes might not
completely eradicate nodal metastases, TME surgery
with lateral lymph node clearance might be justified.
Quality assurance. The resected tumour specimen can
be used to judge the quality of surgery; if the margin
around the specimen is free of cancer cells in both
colon and rectal cancer, the surgery is considered
high quality169,170. The removal and assessment of the
lymph nodes is another guide for determining whether
the mesocolic or mesorectal resection is adequate149.
Internationally, removal of 12 lymph nodes is viewed
as the cut-off value needed to provide adequate histo-
pathological staging; the lymph nodes can also be used
to prognosticate patients. However, the role of proce-
dures to remove the sentinel node (the first lymph node
or group of nodes draining the cancer) in colorectal
cancer is still unclear.
Furthermore, quality assurance in colorectal
c ancer care has been defined for several aspects of
the care continuum: performing trials, working in
multidisciplinary teams, integrated care pathways,
shared decision making, auditing cancer care, central-
ization of complex procedures and international com-
parison of cancer outcomes. Auditing is a powerful
instrument to improve cancer care. Especially for rectal
cancer, survival and local recurrences have been shown
to drastically improve with national auditing initia-
tives146,185,186. To reduce the differences in Europe, an
international, multidisciplinary, outcome-based qual-
ity improvement project — European Registration of
Cancer Care (EURECCA) — was launched in 2007
(REF.152). EURECCA aims to capture the best practices
and promote uniform structured data collection and
analysis to study outcomes of all patients with cancer.
Although these analyses are used for feedback for sur-
geons on the best techniques at hand, volume is another
issue that has been shown to improve patient outcome
in colorectal cancer management187.
Recovery after surgery. Perioperative protocols such
as fast-track protocols and Enhanced Recovery After
Surgery have been designed to minimize surgical com-
plications188,189. The protocol describes the perioperative
care pathway and lists elements of care for patients at
various steps in the perioperative process. Considering
these elements are supported by evidence to improve
recovery time after surgery, Enhanced Recovery after
Surgery was first implemented for patients undergoing
colectomy190 and includes elements such as preoperative
counselling and bowel preparation, perioperative fluid
management and the prevention of ileus (that is, obsti-
pation and intolerance to oral intake), and post operative
glucose control and early mobilization. Indeed, for
patients at high risk of postoperative ileus, enteral
n utrition should be anticipated even before surgery191.
Systemic treatments for primary disease
The systemic treatment of patients with colorectal
cancer has substantially developed over the past two
decades, with major improvements in the neoadjuvant
setting for rectal cancer and the adjuvant setting for
cancer of thecolon.
Neoadjuvant treatment. There is no accepted neo-
adjuvant treatment for colon cancer. However, for
rectal cancer, neoadjuvant radiotherapy or chemo-
radiotherapy are recommended for intermediate-stage
and advanced-stage cancer (for example, very low-tract
anteriorly located cT2 lesions, most T3 lesions, some
T4a lesions with limited peritoneal involvement, N+
lesions, cT3 lesions that invade the mesorectal fascia,
and cT4a and cT4b lesions with positive lateral nodes)
to reduce the rate of local recurrence. The neoadjuvant
treatment can either be given as short-course radio-
therapy followed by surgery or as chemoradiotherapy
with 5-fluorouracil or capecitabine (an oral fluoro-
pyrimidine). Although preoperative radiotherapy or
chemoradiotherapy is more effective than postopera-
tive treatment in reducing local recurrence, it does not
improve overall survival176,192. Strategies that aimed to
improve neoadjuvant treatment by intensifying the
Rectum
Rectal serosa
Rectal mucosa
Plane of dissection
mesorectal fascia
Bladder
Ureter
Seminal vesicle
Sacral spinal
nerve 3
Sacrum
Piriformis
muscle
Internal iliac artery
Pudendal nerve
Inferior hypogastric
plexus
Pelvic splanchnic
nerve
Hypogastric
nerve
Obturator lymph
node
Internal iliac node
Mesorectum
Nature Reviews | Disease Primers
Sympathetic
trunk
Prostate
Sympathetic
ganglion
Figure 7 | Surgical planes for rectal surgery. The plane between the urogenitoury
structures (the prostate, urethra and seminal vesicle in men, and the vagina, uterus and
ovaries in women) and the rectum is called Denonvilliers’ fascia. The dissection plane of
the total mesorectal excision is sharp around the mesorectal fascia and surrounds the
mesorectal fat, in which the draining lymph nodes and the rectum are located. The plane
is avascular, and avoids the parasympatethic and sympathetic nerves in the pelvic lateral
space, which coordinate sexual and urinary function. The superior hypogastric plexus is
formed at the level of the sacral promontory, distally dividing in the hypogastric nerves.
Together with the parasympathetic erigente nerves, these form the inferior hypogastric
(pelvic) plexus, which should not be clamped during surgery to avoid damage. The
pudendal nerve innervates the external sphincter, puborectalis muscle and external
genitalia, among other structures.
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chemoradiotherapy regimen (for example, by combin-
ing 5-fluorouracil and oxaliplatin with radiotherapy
instead of using 5-fluorouracil with radiotherapy)
did not exhibit clear survival benefit, but increased
t oxicity193; more research isneeded.
Adjuvant treatment. The cure rate by surgery alone
for T3, T4a, T4b and N0M0 colon cancers (Union for
International Cancer Control (UICC) stage II) is high,
and only approximately 5% of patients bene fit from
adjuvant chemotherapy. However, guidelines endorsed
by European and Japanese societies recommend
consider ing adjuvant therapy in high-risk cases (that is,
poorly differentiated tumours; when <12lymph nodes
were resected; in cases with vascular, lymphatic or peri-
neural tumour invasion; in cases with obstructiveor
perforated tumours; or with pT4 stage tumours)194.
By contrast, adjuvant treatment is standard for UICC
stageIII tumours (any T, N1–2 (3 or more positive
nodes) and M0); a combination of 5-fluorouracil plus
oxaliplatin is used (orally, as in the XELOX protocol
(capecitabine and oxaliplatin), or intravenously as in
the FOLFOX4 protocol (leucovorin, 5-fluorouracil and
oxaliplatin)). Currently, no data support that the addi-
tion of targeted therapies (such as epidermal growth
factor receptor (EGFR)-specific or vascular endothelial
growth factor (VEGF)-specific monoclonal antibodies)
improves the outcome for patients in the adjuvant set-
ting194. Data from pooled analyses suggest that patients
>70years of age might not benefit profoundly from
oxaliplatin-based chemotherapy combinations in the
adjuvant setting. These patients may benefit from
fluoropyrimidine chemotherapy, similar to younger
patients195. For rectal cancer, postoperative chemo-
radiotherapy can be applied if no preoperative treat-
ment was given and if certain risk factors (including
positive resection margins, perforation in the tumour
area or defects in the mesorectum) are present; a djuvant
chemotherapy typically uses fluoropyrimidines.
Metastatic disease
The survival of patients with metastatic disease has
substantially improved over the past two decades,
and a median overall survival of 30months has been
achieved in clinical trials. This improvement in sur-
vival can be attributed to the use of chemotherapeutics
such as oxaliplatin and irinotecan, the introduction of
targeted therapies that address specific properties of the
tumour or its microenvironment and the incorpor ation
of multidisciplinary approaches, including s urgical
resection of liver metastases.
Chemotherapy combinations. The chemotherapy
backbone for first-line treatment of metastatic disease
is typically a combination of leucovorin, 5- fluorouracil
and either oxaliplatin (FOLFOX protocol) or irino tecan
(FOLFIRI protocol). 5-Fluorouracil in the FOLFOX reg-
imen can be replaced by capecitabine, but the combina-
tion of capecitabine with irinotecan is more toxic than
FOLFIRI. Doublet (two chemotherapeutic agents) and
triplet (three chemotherapeutic agents) chemotherapy
regimens comprising leucovorin, 5- fluorouracil,
oxaliplatin and irinotecan (the FOLFOXIRI protocol)
have been shown to be efficacious196. As compared
with single-agent fluoropyrimidine, combination
chemotherapy achieves better tumour growth control.
However, elderly and frail patients in particular might
benefit from a sequential approach with initial single-
agent fluoropyrimidine chemotherapy or combined
fluoro pyrimidine with VEGF-A-targeted therapy (for
e xample, bevacizumab; see below).
Targeted therapies. Alongside these combined chemo-
therapy regimens, targeted agents are used for meta-
static colorectal cancer treatment. In particular, these
include three main groups of drugs: monoclonal anti-
bodies against EGFR (cetuximab and panitumumab),
monoclonal antibodies against VEGF-A (bevaci-
zumab), and fusion proteins that target multiple pro-
angiogenic growth factors (for example, aflibercept)
and small-molecule-based multikinase inhibitors (for
example, regorafenib).
Approximately 80% of all colorectal cancers express
or overexpress EGFR; overexpression correlates with
reduced survival and increased risk of metastases. The
EGFR tyrosine kinase can be blocked by mono cloncal
antibodies specific to the extracellular domain of
thereceptor, decoy receptors that bind to and block the
soluble ligand, or small molecules that inhibit recep-
tor dimerization or fit into the ATP-binding pocket of
its cytoplasmic tyrosine kinase domain. Most clinical
data in colorectal cancer are available for receptor-
blocking antibodies, such as cetuximab, which is a
recombinant chimeric monoclonal IgG1 antibody, and
panitumumab, which is a human EGFR-specific anti-
body. These antibodies show efficacy in chemotherapy-
naive patients, as well as in patients whose tumours
are refractory to chemotherapy by improving the
overall response rate of the tumours. These strategies
also improve progression-free survival (PFS) and even
overall survival in patients with metastatic colorectal
cancer. However, a prerequisite for the efficacy of these
agents is that the tumours do not harbour activating
mutations in KRAS and NRAS197,198.
RAS is mutated in about half of all patients with colo-
rectal cancers, with codons 12 and 13 being the most
commonly affected; codons 61 and 146 of KRAS and
codons 12, 13 and 61 of NRAS are affected to a lesser
extent. HRAS mutations have so far not been described
in colorectal cancer. The mutations render the RAS
GTPase constitutively active; active RAS induces a pleth-
ora of tumorigenic intracellular signalling pathways.
Thus, the RAS status of the tumour must be e xamined
before treatment with EGFR-specificantibodies.
Tumours establish a vascular network of their
own once they reach a critical size199. Accordingly, a
key effector of tumour angiogenesis is the secreted
glycoprotein VEGF-A, which binds to VEGF recep-
tor1 (VEGFR1) and VEGFR2. VEGF-A is produced
by many tumour and stromal cells, promotes prolifer-
ation and migration of endothelial cells and increases
vessel permeability. VEGF is also a growth factor
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for various tumour cells. VEGF-specific therapies
are used in metastatic colorectal cancer, but the pre-
cise mechanisms of action are not fully understood.
These compounds might act by normalizing the dys-
regulated tumour vasculature, which would lead to
improved tumour oxygen ation and delivery of chemo-
therapy200. There are as yet no predictive biomarkers
for anti-angiogenicagents.
Bevacizumab has demonstrated efficacy in com-
bination with chemotherapy in the metastatic set-
ting; combined with 5-fluorouracil and irinotecan,
bevacizumab significantly improved median PFS and
median overall survival of patients in a PhaseIII trial
compared with chemotherapy alone6. The addition
of bevacizumab also significantly improved median
PFS in patients receiving a combination of fluoro-
pyrimidine and oxaliplatin. Interestingly, the combina-
tion of bevacizumab and 5-fluorouracil or oxaliplatin
also yielded a significant improvement in tumour
response, median PFS and median overall survival
compared to chemotherapy alone in patients with
chemo refractory metastatic disease201. Bevacizumab is
also one of the few compounds that confer a survival
benefit to patients when treatment is continued even
after diseaseprogression202.
Aflibercept also targets angiogenesis. This drug
is a recombinant fusion protein that consists of
the VEGF-binding portions from the extracellular
domains of human VEGFR1 and VEGFR2 fused to
the Fc p ortion of human IgG1. Aflibercept also binds
to the placenta growth factor and, therefore, has a
somewhat broader anti-angiogenic activity than beva-
cizumab. Aflibercept has been shown to improve PFS
and overall survival when used in combination with
FOLFIRI in the s econd-line setting for treatment of
metastaticdisease203.
Metastatic resection. For patients with colorectal c ancer
who have isolated liver and/or lung metastases that are
technically R0 resectable, surgery should be consid-
ered — particularly when the metastases are l imited in
n umber and size. The 5-year overall survival rate in this
group is about 20%204,205, an i mpressive figure for meta-
static disease. One clinical trial has used a perioperative
FOLFOX protocol in this group of patients and has shown
an improvement in PFS, but no signifi cant d ifference in
overall survival compared with surgeryalone196.
In the majority of patients with isolated liver and/or
lung metastases, a R0 resection cannot be primarily
achieved. However, if the metastases can be downsized
and combined with adjuvant chemotherapy, the 5-year
overall survival rate is similar to R0 resections206. Inthis
situation, the most active chemotherapy should be
employed to ‘convert’ the disease to a resectable state;
FOLFOXIRI triplet chemotherapy regimen confers high
response rate (approximately 60%)207. In a RAS wild-type
population, chemotherapy doublets plus EGFR-specific
treatment also results in high response rates. According
to data from the FIRE3 study, EGFR-specific anti bodies
in combination with FOLFIRI seem to induce more
pronounced tumour shrinkage than FOLFIRI plus
bevacizumab. Thus, this combination is an option if the
tumour is RAS wild-type208.
If a more-active treatment with the intent to downsize
metastases for secondary resectability is used, it is impor-
tant to ensure that the tumour is regularly re-evaluated
by a multidisciplinary team and resection of metastases
is performed at the earliest time point when an R0 resec-
tion is possible. In doing so, chemotherapy toxicity is
reduced and perioperative morbidity is minimized. The
‘disappearance’ of the metastases on CT imaging does
not necessarily indicate a complete destruction of the
metastases in most patients, and makes it difficult for
thesurgeon to completely resect all lesions209.
Further considerations. Patients with symptomatic or
more-aggressive metastatic disease without chance of
secondary metastatic resection benefit from active first-
line treatment to achieve optimal tumour control. This
can generally be achieved using doublet chemotherapy
in combination with a targeted agent such as bevaci-
zumab. In patients with RAS wild-type tumours, doublet
chemotherapy together with an EGFR-specific antibody
treatment can also be used. For those who respond to
this ‘induction’ treatment, or who have a stable disease
after 4–6months of the treatment, the intensity of the
treatment should be reduced to avoid excessive toxi city.
This is particularly important if a FOLFOX protocol is
used to avoid the cumulative neuro toxicity of oxali-
platin. A PhaseIII trial showed that, after FOLFOX plus
bevacizumab induction therapy, a maintenance strategy
with fluoropyrimidine chemotherapy plus bevacizumab
prolonged PFS without significantly improving overall
survival compared to a complete treatment break210.
Thus, active maintenance, but also treatment discon-
tinuation, can be considered when tumours respond to
or are stable during a 4–6-month induction treatment
and the tumour burden is nothigh.
Box 4 | Supportive palliative care for patients with colorectal cancer
Maintenance of adequate nutrient intake
Surgery and chemoradiotherapy can impair energy intake temporarily or for prolonged
periods. Nutritional counselling and dietary monitoring can improve nutritional status,
which benefits physical condition.
Pain relief
A substantial proportion of patients with advanced‑stage disease require opioid
treatment in the last months of their life. In a large UK study222, approximately 20% of
patients received intense opioid combination therapy. Such pain relief requires
adequate patient monitoring, physician training and access to a dedicated pain
treatment team222.
Physical condition maintenance
Various studies focusing on patients with advanced‑stage colorectal as well as other
cancers have reported that exercise programmes can improve the patient’s physical
condition, mobility and sleep, and reduce fatigue27,223.
Prevention of avoidable hospital admission
A considerable proportion of hospital admissions in patients with advanced‑stage
colorectal cancer are potentially avoidable by adequate support at home and hospice
access. Potentially avoidable admissions seem to occur more often in elderly patients
and those with end‑stage disease.
Psychosocial support
Routine assessment at outpatient clinic visits or visits at home can help to identify
patients who need specific psychosocial support in a timely manner.
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In the palliative setting, a less-aggressive approach with
monotherapy with fluoropyrimidine c hemotherapy or a
combination of fluoropyrimidinechemotherapy with bev-
acizumab is possible. Such a strategy requires the patient
to be at low risk for rapid deterioration. Upon disease pro-
gression, treatment should be escalated and combination
chemotherapy (together with bevacizumab) should be
used. However, recent data from the FIRE3 and CALGB
trials suggest that using a more-intensive treatment in the
first-line setting can achieve a median overall survival of
about 30months in a RAS wild-type p opulation. Such sur-
vival rates have so far not been reported in a sequential
setting when treatment starts with just f luoropyrimidine
chemotherapy with or without bevacizumab196.
In the second-line palliative setting, upon further dis-
ease progression, chemotherapy should be changed to a
regimen that is not used in the first-line setting (either
FOLFOX/XELOX or FOLFIRI). Arecent study showed
that bevacizumab can be given after disease progression
and improves overall survival in the second-line setting202.
Apart from bevacizumab, aflibercept can be used in the
second-line setting (in combination with FOLFIRI).
Cetuximab or panitumumab can also be used if not
previously used and if the tumour is RAS wild-type. For
these compounds, efficacy beyond progression has not
beendemonstrated.
In cancers that are refractory to two lines of chemo-
therapy, EGFR-specific antibodies can be used if the
tumour is RAS wild-type and an EGFR-specific antibody
has not been used previously197. Regorafenib is an orally
available multikinase inhibitor that has shown efficacy in
patients who had previously been treated with all avail-
able therapies. Accordingly, it has become the standard
in pre-treated patients211.
Quality of life
Colorectal cancer can manifestly impair quality of
life through, for example, direct consequences of the
Nature Reviews | Disease Primers
EGF
EGFR2 ERBB2BMPR
TGFβR
WNT
LRP
Frizzled PIP2
PI3K
PIP3
AKT
AKT
P
PDK
PX-866
BKM120
SF1126
GSK1059615
XL147
GDC-0941
Combination
therapy
CI-1040
MEK162
SMAD1/2 SMAD1/5/8SMAD1/2
P
SMAD1/5/8
P
SFRP
PTEN
Axin
GSK3 CK1
APC
Dsh
PRI-724
Cell growth
Cell survival
Motility
Metabolism
Cell cycle
control
Transcription
Transcription factors
for example, c-MYC
Cytoplasm
Nucleus
WNT974 Antisense
oligonucleotides
Receptor kinase
inhibitors
Cetuximab
Panitumumab
TGFβBMP
SMAD4
β-Catenin mTOR
RAF
N/KRAS
MEK
MAPK
Figure 8 | Emerging drug targets and drug candidates in colorectal cancer. The Cancer Genome Atlas and various
other genomics projects have identified several novel potential molecular targets and markers in colorectal cancer that
might be used to guide specific treatments for subgroups of patients. These targets include the WNT, transforming growth
factor-β (TGFβ) and epidermal growth factor receptor (EGFR) signalling pathways. Experimental agents that target these
molecules are included in grey boxes. APC, adenomatous polyposis coli; BMP, bone morphogenetic protein; BMPR,
BMPreceptor; CK1, casein kinase 1; Dsh, Dishevelled; GSK3, glycogen synthase kinase 3; LRP, low-density lipoprotein
receptor-related protein; MAPK, mitogen-activated protein kinase; mTOR, mammalian target of rapamycin; P(in a red
circle), phosphate; PDK, 3-phosphoinositide-dependent protein kinase; PI3K, phosphatidylinositol 3-kinase; PIP2,
phosphatidylinositol-4,5-bisphosphate; PIP3, phosphatidylinositol-3,4,5-trisphosphate; PTEN, phosphatase and tensin
homologue; SFRP, secreted frizzled-related protein; SMAD, SMAD family member; TGFβR, TGFβ receptor.
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disease, such as abdominal pain, change in bowel move-
ments, blood loss and anaemia, fatigue and weight loss.
Furthermore, treatment incurs a burden to quality
of life by means of surgery, chemotherapy and radio-
therapy, which can be associated in the short term
with impaired nutrient intake and physical activity212.
Indeed, weight loss and reduced physical condition is
particularly relevant for elderly patients and those with
co- morbidities, and should be adequately monitored
during treatmen tand follow-upcare.
Each treatment modality can be associated with
further specific adverse effects and complications. One
of the most feared surgical complications is the occur-
rence of leakage of the anastomosis, at the suture line of
the intestinal loops after removal of the tumour. This
event usually requires further surgical or radiological
intervention and is associated with significant morbid-
ity, lengthening of hospital stay and mortality. Other
more-common complications of surgery are wound
dehiscence (that is, rupture of the wound along a surgi-
cal suture) and abdominal scar herniation. Overall, the
effect on quality of life does not differ between open
and laparoscopic surgery130. A range of stoma-related
complications can also substantially impair social func-
tioning and quality of life; these can sometimes be man-
aged conservatively, but may require surgical revision
of thestoma.
Treatment for rectal cancer is frequently associated
with long-term complications. These include faecal
incontinence and increased numbers of stools. These
complications are well defined in the validated low
a nterior resection syndrome score213. Pelvic floor prob-
lems are more frequent in patients with rectal cancer
receiving neoadjuvant chemoradiotherapy or radio-
therapy214. Toxicity is higher after chemoradiotherapy
in comparison to radiotherapy alone215. Moreover, erec-
tile dysfunction in men and dyspareunia in women are
c ommon after rectal cancer treatment216,217.
With respect to chemotherapy, 5-fluorouracil is usu-
ally well tolerated, but oxaliplatin or irinotecan more
often give rise to adverse effects, such as neutropenia
and diarrhoea. Targeted therapies have important
adverse effects that must be considered. For the EGFR-
specific antibodies, papulopustular rash and paronychia
(infection of the nail) occur within days of treatment,
followed by skin atrophy after several weeks and alo-
pecia that occurs within a few months. High-grade
skin toxicity can involve pain and secondary infec-
tions. Anti-angiogenic agents cause bleeding, arterial
thrombo embolic events, impaired wound healing,
hypertension and proteinuria6. Aflibercept increases
(to some extent) chemotherapy-induced adverse events,
such as d iarrhoea, neutropenia and asthenia203.
Metastatic disease can give rise to a range of addi-
tional symptoms that affect quality of life, such as
cachexia, loss of appetite, anaemia, liver failure, bili-
ary obstruction and impaired pulmonary function218.
These symptoms relate to duration of survival to some
extent218. A range of interventions, with focus on the
management of pain, improvement of food intake and
maintenanceof physical activity benefit individual
patient groups. For example, a systematic review of
three studies reported that increased physical activ-
ity improved quality of life in patients with colorectal
c ancer219. Clinicians are aware of the potential major
impact of colorectal cancer on many aspects of qual-
ity of life, and individualized options to improve this
should be given220 (BOX4).
Outlook
Over the past several decades, colorectal cancer has
become one of the most common cancers, and its inci-
dence is expected to continue to increase in coming
years. Despite major advances in treatment, mortal-
ity from colorectal cancer remains high and 40–50%
of patients eventually die because of their disease. As
discussed above, colorectal cancer arises as a result of
environmental factors and genetic factors cooperat-
ing to generate colon polyps that progress to colo rectal
cancer. The polyp to cancer progression sequence is
primarily driven at the cellular level by gene muta-
tions and epi genetic alterations, and is now recognized
to be a hetero geneous process. It is widely anticipated
that insights into the unique gene mutations will lead
to more-precise and individualized care for p eople
with polyps and cancers, which will be guided by
the m olecular characterization of the individual’s
colontumour.
The future of cancer surgery for colorectal disease
is aimed at minimizing surgical trauma and preserving
organ function. Population-based studies to unravel the
effects of multimodal strategies for elderly patients and
those with co-morbidities need to be undertaken. High-
precision imaging will lead to image-guided techniques.
Each patient is unique and surgery needs to be tailor-
made, aimed at complete removal for cure. Feedback
on performance is required to keep on improving
ourefforts.
Chemotherapy has made substantial progress in
recent years. We can now individualize the treatment
according to the type of metastases (isolated liver or
lung metastases, resectable or primarily not resectable),
the RAS mutation state of the tumour and the response
to a given treatment (for maintenance strategies or
thera peutic breaks). The Cancer Genome Atlas and
various other genomic projects have identified several
novel potential molecular targets and markers for colo-
rectal cancer that might be used to guide more-specific
treatments for s ubgroups of patients (FIG.8).
These developments in surgery and chemoradio-
therapy or radiotherapy will improve and further
individ ualize treatment in the near future, which should
prolong the survival of patients. However, the largest
impact on incidence and mortality will come from
widespread organized population screening. Screening
programmes should aim for optimal uptake and smart
use of available resources. Opportunistics creeningpro-
grammes must be replaced by organized s creening,
together with the incorporation of strict quality-
assurance measures. With such an approach, the
foreseen rapid rise in colorectal cancer incidence and
mortality could be reversed in the comingdecade.
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1. Kuipers,E.J., Rösch,T. & Bretthauer,M. Colorectal
cancer screening — optimizing current strategies and
new directions. Nat. Rev. Clin. Oncol. 10, 130–142
(2013).
A review of the current state of the art of colorectal
cancer screening.
2. Warthin,A.S. Heredity with reference to carcinoma:
as shown by the study of the cases examined in the
pathological laboratory of the University of Michigan.
Arch. Intern. Med. 12, 546–555 (1913).
3. Capelle,L.G. etal. Risk and epidemiological time
trends of gastric cancer in Lynch syndrome carriers
inthe Netherlands. Gastroenterology 138, 487–492
(2010).
4. Vasen,H.F.A., Tomlinson,I. & Castells,A. Clinical
management of hereditary colorectal cancer
syndromes. Nat. Rev. Gastroenterol. Hepatol. 12,
88–97 (2015).
5. Papamichael,D. etal. Treatment of colorectal cancer
in older patients: International Society of Geriatric
Oncology (SIOG) consensus recommendations 2013.
Ann. Oncol. 26, 463–476 (2014).
6. Hurwitz,H. etal. Bevacizumab plus irinotecan,
fluorouracil, and leucovorin for metastatic colorectal
cancer. N.Engl. J.Med. 350, 2335–2342 (2004).
7. Heemskerk-Gerritsen,B.A.M. etal. Improved overall
survival after contralateral risk-reducing mastectomy
in BRCA1/2 mutation carriers with a history of
unilateral breast cancer: aprospective analysis.
Int.J.Cancer 136, 668–677 (2015).
8. DeJonge,V. etal. Quality evaluation of colonoscopy
reporting and colonoscopy performance in daily
clinical practice. Gastrointest. Endosc. 75, 98–106
(2012).
9. Valori,R. etal. European guidelines for quality
assurance in colorectal cancer screening and
diagnosis. First Edition — quality assurance in
endoscopy in colorectal cancer screening and
diagnosis. Endoscopy 44, SE88–SE105 (2012).
This paper describes the results of extensive
international consensus on quality-assurance
measures for colorectal cancer screening.
10. GLOBOCAN. GLOBOCAN 2012: estimated cancer
incidence, mortality and prevalence worldwide in
2012. GLOBOCAN [online], http://globocan.iarc.fr/
Default.aspx (2015).
11. Rohani-Rasaf,M., Abdollahi,M., Jazayeri,S.,
Kalantari,N. & Asadi-Lari,M. Correlation of cancer
incidence with diet, smoking and socio-economic
position across 22 districts of Tehran in 2008.
AsianPac. J.Cancer Prev. 14, 1669–1676 (2013).
12. Draft,C. etal. Global, regional and national levels
ofage-specific mortality and 240 causes of death,
1990–2013: asystematic analysis for the Global
Burden of Disease Study 2013. Lancet 385,
1990–2013 (2015).
13. Tiwari,A.K., Roy,H.K. & Lynch,H.T. Lynch syndrome
in the 21st century: clinical perspectives. QJM
http://dx.doi.org/10.1093/qjmed/hcv137 (2015).
14. Pérez-Carbonell,L. etal. Comparison between
universal molecular screening for Lynch syndrome
andrevised Bethesda guidelines in a large population-
based cohort of patients with colorectal cancer. Gut
61, 865–872 (2012).
15. Van Lier,M.G.F. etal. Yield of routine molecular
analyses in colorectal cancer patients ≤70years to
detect underlying Lynch syndrome. J.Pathol. 226,
764–774 (2012).
16. Jess,T., Rungoe,C. & Peyrin-Biroulet,L. Risk of
colorectal cancer in patients with ulcerative colitis:
ameta-analysis of population-based cohort studies.
Clin. Gastroenterol. Hepatol. 10, 639–645 (2012).
17. Jess,T. etal. Decreasing risk of colorectal cancer
inpatients with inflammatory bowel disease over
30years. Gastroenterology 143, 375–381.e1
(2012).
18. Castaño-Milla,C., Chaparro,M. & Gisbert,J.P.
Systematic review with meta-analysis: the declining
risk of colorectal cancer in ulcerative colitis.
Aliment.Pharmacol. Ther. 39, 645–659 (2014).
19. Herrinton,L.J. etal. Incidence and mortality
ofcolorectal adenocarcinoma in persons with
inflammatory bowel disease from 1998 to 2010.
Gastroenterology 143, 382–389 (2012).
20. World Cancer Research Fund/American Institute for
Cancer Research. Continuous update project report.
Food, nutrition, physical activity, and the
preventionofcolorectal cancer. Diet and Cancer
Report [online], http://www.dietandcancerreport.org/
cancer_resource_center/downloads/cu/Colorectal-
Cancer-2011-Report.pdf (2011).
21. Guraya,S.Y. Association of type2 diabetes mellitus
and the risk of colorectal cancer: ameta-analysis
andsystematic review. World J.Gastroenterol. 21,
6026–6031 (2015).
22. Fedirko,V. etal. Alcohol drinking and colorectal
cancer risk: an overall and dose-response meta-
analysis of published studies. Ann. Oncol. 22,
1958–1972 (2011).
23. Liang,P.S., Chen,T.-Y. & Giovannucci,E. Cigarette
smoking and colorectal cancer incidence and
mortality: systematic review and meta-analysis.
Int.J.Cancer 124, 2406–2415 (2009).
24. Botteri,E. etal. Smoking and colorectal cancer:
ameta-analysis. JAMA 300, 2765–2778 (2008).
25. Song,M., Garrett,W.S. & Chan,A.T. Nutrients, foods,
and colorectal cancer prevention. Gastroenterology
148, 1244–1260.e16 (2015).
An extensive review of the current knowledge
onnutrients and colorectal cancer risk as well
asprevention.
26. Dahm,C.C. etal. Dietary fiber and colorectal cancer
risk: anested case–control study using food diaries.
102, 614–626 (2010).
27. Arem,H. etal. Physical activity and cancer-specific
mortality in the NIH-AARP Diet and Health Study
cohort. Int. J.Cancer 135, 423–431 (2014).
28. Algra,A.M. & Rothwell,P.M. Effects of regular
aspirin on long-term cancer incidence and metastasis:
asystematic comparison of evidence from
observational studies versus randomised trials.
LancetOncol. 13, 518–527 (2012).
29. Doubeni,C.A. etal. Contribution of behavioral risk
factors and obesity to socioeconomic differences in
colorectal cancer incidence. J.Natl Cancer Inst. 104,
1353–1362 (2012).
30. Erdrich,J., Zhang,X., Giovannucci,E. & Willett,W.
Proportion of colon cancer attributable to lifestyle
inacohort of US women. Cancer Causes Control 26,
1271–1279 (2015).
31. Platz,E.A. etal. Proportion of colon cancer risk that
might be preventable in a cohort of middle-aged US
men. Cancer Causes Control 11, 579–588 (2000).
32. Aleksandrova,K. etal. Combined impact of healthy
lifestyle factors on colorectal cancer: alarge European
cohort study. BMC Med. 12, 168 (2014).
33. Andersen,V. & Vogel,U. Systematic review:
interactions between aspirin, and other nonsteroidal
anti-inflammatory drugs, and polymorphisms in
relation to colorectal cancer. Aliment. Pharmacol.
Ther. 40, 147–159 (2014).
34. Nan,H. etal. Association of aspirin and NSAID use
with risk of colorectal cancer according to genetic
variants. JAMA 313, 1133–1142 (2015).
A large study combining data from multiple case–
control and cohort studies looking at the preventive
effect of aspirin and NSAID use on the risk of
colorectal cancer.
35. Bardou,M., Barkun,A. & Martel,M. Effect of statin
therapy on colorectal cancer. Gut 59, 1572–1585
(2010).
A review on the preventive effects of statin therapy
on the development of colorectal cancer.
36. Liu,Y. etal. Association between statin use and
colorectal cancer risk: ameta-analysis of 42studies.
Cancer Causes Control 25, 237–249 (2014).
37. Limsui,D. etal. Postmenopausal hormone therapy and
colorectal cancer risk by molecularly defined subtypes
among older women. Gut 61, 1299–1305 (2012).
38. Ogino,S., Chan,A.T., Fuchs,C.S. & Giovannucci,E.
Molecular pathological epidemiology of colorectal
neoplasia: anemerging transdisciplinary and
interdisciplinary field. Gut 60, 397–411 (2011).
39. Hanahan,D. & Weinberg,R.A. The hallmarks of
cancer. Cell 100, 57–70 (2000).
40. Hanahan,D. & Weinberg,R.A. Hallmarks of cancer:
the next generation. Cell 144, 646–674 (2011).
41. Colussi,D., Brandi,G., Bazzoli,F. & Ricciardiello,L.
Molecular pathways involved in colorectal cancer:
implications for disease behavior and prevention.
Int.J.Mol. Sci. 14, 16365–16385 (2013).
42. Grady,W.M. & Carethers,J.M. Genomic and
epigenetic instability in colorectal cancer
pathogenesis. Gastroenterology 135, 1079–1099
(2008).
43. Fearon,E.R. & Vogelstein,B. A genetic model for
colorectal tumorigenesis. Cell 61, 759–767 (1990).
44. Lengauer,C., Kinzler,K.W. & Vogelstein,B. Genetic
instabilities in human cancers. Nature 396, 643–649
(1998).
45. Kinzler,K.W. & Vogelstein,B. Lessons from hereditary
colorectal cancer. Cell 87, 159–170 (1996).
46. Zeki,S.S., Graham,T.A. & Wright,N.A. Stem cells
and their implications for colorectal cancer. Nat. Rev.
Gastroenterol. Hepatol. 8, 90–100 (2011).
47. Jones,S. etal. Comparative lesion sequencing
provides insights into tumor evolution. Proc. Natl
Acad. Sci. USA 105, 4283–4288 (2008).
48. Luo,Y. etal. Differences in DNA methylation
signatures reveal multiple pathways of progression
from adenoma to colorectal cancer. Gastroenterology
147, 418–429.e8 (2014).
49. VanEngeland,M., Derks,S., Smits,K.M., Meijer,G.A.
& Herman,J.G. Colorectal cancer epigenetics: complex
simplicity. J.Clin. Oncol. 29, 1382–1391 (2011).
50. Goldstein,N.S. Serrated pathway and APC
(conventional)-type colorectal polyps: molecular–
morphologic correlations, genetic pathways, and
implications for classification. Am. J.Clin. Pathol. 125,
146–153 (2006).
51. Jass,J.R. Hyperplastic polyps and colorectal cancer:
isthere a link? Clin. Gastroenterol. Hepatol. 2, 1–8
(2004).
52. Bettington,M. etal. The serrated pathway to
colorectal carcinoma: current concepts and challenges.
Histopathology 62, 367–386 (2013).
53. Rex,D.K. etal. Serrated lesions of the colorectum:
review and recommendations from an expert panel.
Am. J.Gastroenterol. 107, 1315–1329 (2012).
Expert panel recommendations for the detection
and management of serrated colorectal polyps.
54. Kambara,T. etal. BRAF mutation is associated with
DNA methylation in serrated polyps and cancers
ofthe colorectum. Gut 53, 1137–1144 (2004).
55. Noffsinger,A.E. Serrated polyps and colorectal
cancer: new pathway to malignancy. Annu. Rev. Pathol.
4, 343–364 (2009).
56. Cancer Genome Atlas Network. Comprehensive
molecular characterization of human colon and
rectalcancer. Nature 487, 330–337 (2012).
57. Chittenden,T.W. etal. Functional classification
analysis of somatically mutated genes in human breast
and colorectal cancers. Genomics 91, 508–511
(2008).
58. Jubb,A.M., Bell,S.M. & Quirke,P. Methylation and
colorectal cancer. J.Pathol. 195, 111–134 (2001).
59. Starr,T.K. etal. A transposon-based genetic screen
inmice identifies genes altered in colorectal cancer.
Science 323, 1747–1750 (2009).
60. Parsons,D.W. etal. Colorectal cancer: mutations
inasignalling pathway. Nature 436, 792 (2005).
61. Brennan,C.W. etal. The somatic genomic landscape
of glioblastoma. Cell 155, 462–477 (2013).
62. Grady,W.M. & Pritchard,C.C. Molecular alterations
and biomarkers in colorectal cancer. Toxicol. Pathol.
42, 124–139 (2014).
A review on the molecular pathways that lead to
colorectal cancer.
63. Bardelli,A. etal. Mutational analysis of the tyrosine
kinome in colorectal cancers. Science 300, 949
(2003).
64. Lao,V.V. & Grady,W.M. Epigenetics and colorectal
cancer. Nat. Rev. Gastroenterol. Hepatol. 8, 686–700
(2011).
65. Kim,Y.-H. etal. CpG island methylation of genes
accumulates during the adenoma progression step of
the multistep pathogenesis of colorectal cancer.
GenesChromosomes Cancer 45, 781–789 (2006).
66. Bird,A. The essentials of DNA methylation. Cell 70,
5–8 (1992).
67. Worthley,D.L. etal. DNA methylation within the
normal colorectal mucosa is associated with
pathway-specific predisposition to cancer. Oncogene
29, 1653–1662 (2010).
68. Yamauchi,M. etal. Assessment of colorectal cancer
molecular features along bowel subsites challenges
the conception of distinct dichotomy of proximal
versus distal colorectum. Gut 61, 847–854 (2012).
A study showing the correlation between the
molecular features of colorectal cancer and
thelocation of the tumour.
69. Rosty,C. etal. PIK3CA activating mutation in
colorectal carcinoma: associations with molecular
features and survival. PLoS ONE 8, e65479 (2013).
70. Galon,J. etal. Towards the introduction of the
“Immunoscore” in the classification of malignant
tumours. J.Pathol. 232, 199–209 (2014).
71. Kostic,A.D. etal. Genomic analysis identifies
association of Fusobacterium with colorectal
carcinoma. Genome Res. 22, 292–298 (2012).
72. Tahara,T. etal. Fusobacterium in colonic flora
andmolecular features of colorectal carcinoma.
Cancer Res. 74, 1311–1318 (2014).
PRIMER
22
|
2015
|
VOLUME 1 www.nature.com/nrdp
© 2015 Macmillan Publishers Limited. All rights reserved

73. Mima,K. etal. Fusobacterium nucleatum and Tcells
in colorectal carcinoma. JAMA Oncol. 1, E1–E9
(2015).
74. Morris,E.J.A., Rutter,M.D., Finan,P.J.,
Thomas,J.D. & Valori,R. Post-colonoscopy colorectal
cancer (PCCRC) rates vary considerably depending on
the method used to calculate them: aretrospective
observational population-based study of PCCRC in the
English National Health Service. Gut 64, 1248–1256
(2014).
75. Kaminski,M.F. etal. Quality indicators for
colonoscopy and the risk of interval cancer. N.Engl.
J.Med. 362, 1795–1803 (2010).
The first study to show that the risk of
post-colonoscopy cancer is higher when the
colonoscopy was performed by an endoscopist
withlow adenoma detection rates.
76. Zauber,A.G. etal. Colonoscopic polypectomy and
long-term prevention of colorectal-cancer deaths.
N.Engl. J.Med. 366, 687–696 (2012).
This study is a long-term follow-up of the National
Polyp Study, showing persistently lower mortality
ofcolorectal cancer after colonoscopy with
adenoma removal.
77. Pox,C.P. etal. Efficacy of a nationwide screening
colonoscopy program for colorectal cancer.
Gastroenterology 142, 1460–1467.e2 (2012).
78. Winawer,S.J. etal. Prevention of colorectal cancer
bycolonoscopic polypectomy. The National Polyp
Study Workgroup. N.Engl. J.Med. 329, 1977–1981
(1993).
79. Nishihara,R. etal. Long-term colorectal-cancer
incidence and mortality after lower endoscopy.
N.Engl. J.Med. 369, 1095–1105 (2013).
80. Corley,D. A. etal. Adenoma detection rate and risk
ofcolorectal cancer and death. N.Engl. J.Med. 370,
1298–1306 (2014).
This paper provides important confirmation
thatthe risk of colorectal cancer and death
withlong-term follow-up after colonoscopy relates
to adenoma detection rates.
81. Sanduleanu,S. etal. Definition and taxonomy
ofinterval colorectal cancers: aproposal for
standardising nomenclature. Gut 64, 1257–1267
(2015).
82. Nagorni,A., Bjelakovic,G. & Petrovic,B. Narrow band
imaging versus conventional white light colonoscopy
for the detection of colorectal polyps.
CochraneDatabase Syst. Rev. 1, CD008361 (2012).
83. Pohl,J. etal. Pancolonic chromoendoscopy with indigo
carmine versus standard colonoscopy for detection
ofneoplastic lesions: arandomised two-centre trial.
Gut 60, 485–490 (2010).
84. Waye,J.D. etal. A retrograde-viewing device improves
detection of adenomas in the colon: aprospective
efficacy evaluation (with videos). Gastrointest. Endosc.
71, 551–556 (2010).
85. Leufkens,A.M. etal. Effect of a retrograde-viewing
device on adenoma detection rate during colonoscopy:
the TERRACE study. Gastrointest. Endosc. 73,
480–489 (2011).
86. DeMarco,D.C. etal. Impact of experience with a
retrograde-viewing device on adenoma detection rates
and withdrawal times during colonoscopy: the Third
Eye Retroscope Study Group. Gastrointest. Endosc.
71, 542–550 (2010).
87. VanGossum,A. etal. Capsule endoscopy versus
colonoscopy for the detection of polyps and cancer.
N.Engl. J.Med. 361, 264–270 (2009).
88. Spada,C. etal. Second-generation colon capsule
endoscopy compared with colonoscopy.
Gastrointest.Endosc. 74, 581–589.e1 (2011).
89. Spada,C. etal. Meta-analysis shows colon capsule
endoscopy is effective in detecting colorectal polyps.
Clin. Gastroenterol. Hepatol. 8, 516–522.e8 (2010).
90. Spada,C. etal. Colon capsule endoscopy: European
Society of Gastrointestinal Endoscopy (ESGE)
Guideline. Endoscopy 44, 527–536 (2012).
91. Rex,D.K. etal. Accuracy of capsule colonoscopy in
detecting colorectal polyps in a screening population.
Gastroenterology 148, 948–957.e2 (2015).
92. Sung,J.J.Y. etal. An updated Asia Pacific Consensus
Recommendations on colorectal cancer screening. Gut
64, 121–132 (2014).
93. Kim,D.H. etal. CT colonography versus colonoscopy
for the detection of advanced neoplasia. N.Engl.
J.Med. 357, 1403–1412 (2007).
94. Pickhardt,P.J., Hassan,C., Halligan,S. & Marmo,R.
Colorectal cancer: CT colonography and colonoscopy
for detection — systematic review and meta-analysis.
Radiology 259, 393–405 (2011).
95. Spada,C. etal. Colon capsule versus CT colonography
in patients with incomplete colonoscopy:
aprospective, comparative trial. Gut 64, 272–281
(2015).
96. Park,S.H. etal. CT colonography for detection and
characterisation of synchronous proximal colonic
lesions in patients with stenosing colorectal cancer.
Gut 61, 1716–1722 (2012).
97. Plumb, A.A. etal. CT colonography in the English
Bowel Cancer Screening Programme: national survey
of current practice. Clin. Radiol. 68, 479–487 (2013).
98. DeWijkerslooth,T.R. etal. Burden of colonoscopy
compared to non-cathartic CT-colonography in
acolorectal cancer screening programme: randomised
controlled trial. Gut 61, 1552–1559 (2012).
99. DeHaan,M.C., vanGelder,R.E., Graser,A., Bipat,S.
& Stoker,J. Diagnostic value of CT-colonography
ascompared to colonoscopy in an asymptomatic
screening population: ameta-analysis. Eur. Radiol. 21 ,
1747–1763 (2011).
100. Pooler,B.D., Kim,D.H., Lam,V.P., Burnside,E.S.
&Pickhardt,P.J. CT Colonography Reporting and
Data System (C-RADS): benchmark values from
aclinical screening program. Am. J.Roentgenol. 202,
1232–1237 (2014).
101. Stoop,E.M. etal. Participation and yield of
colonoscopy versus non-cathartic CT colonography
inpopulation-based screening for colorectal cancer:
arandomised controlled trial. Lancet Oncol. 13,
55–64 (2012).
102. Yee,J. etal. ACR Appropriateness Criteria colorectal
cancer screening. J.Am. Coll. Radiol. 11, 543–551
(2014).
103. Spada,C. etal. Clinical indications for computed
tomographic colonography: European Society of
Gastrointestinal Endoscopy (ESGE) and European
Society of Gastrointestinal and Abdominal Radiology
(ESGAR) Guideline. Endoscopy 46, 897–915 (2014).
104. Grützmann,R. etal. Sensitive detection of colorectal
cancer in peripheral blood by septin9 DNA
methylation assay. PLoS ONE 3, e3759 (2008).
105. Church,T.R. etal. Prospective evaluation of
methylated SEPT9 in plasma for detection of
asymptomatic colorectal cancer. Gut 63, 317–325
(2014).
106. Ahlquist,D.A. etal. Stool DNA and occult blood
testing for screen detection of colorectal neoplasia.
Ann. Intern. Med. 149, 441–450 (2008).
107. Imperiale,T.F. etal. Multitarget stool DNA testing
forcolorectal-cancer screening. N.Engl. J.Med. 370,
1287–1297 (2014).
108. Bosch,L.J.W. etal. Molecular tests for colorectal
cancer screening. Clin. Colorectal Cancer 10, 8–23
(2011).
109. Kuipers,E.J. Colorectal cancer: screening — one small
step for mankind, one giant leap for man. Nat. Rev.
Clin. Oncol. 11, 5–6 (2014).
110 . Brenner,H., Altenhofen,L., Stock,C. &
Hoffmeister,M. Natural history of colorectal
adenomas: birth cohort analysis among 3.6million
participants of screening colonoscopy. Cancer
Epidemiol. Biomarkers Prev. 22, 1043–1051 (2013).
111. Schreuders,E.H. etal. Colorectal cancer screening:
aglobal overview of existing programmes. Gut 64,
1637–1649 (2015).
A review of existing colorectal cancer
programmesworldwide.
112 . Singh,H. etal. The reduction in colorectal cancer
mortality after colonoscopy varies by site of the
cancer. Gastroenterology 139, 1128–1137 (2010).
113 . Brenner,H., Stock,C. & Hoffmeister,M. Effect of
screening sigmoidoscopy and screening colonoscopy
on colorectal cancer incidence and mortality:
systematic review and meta-analysis of randomised
controlled trials and observational studies. Br. Med.J.
2467, 1–12 (2014).
A systematic review on the long-term effect of
sigmoidoscopy and colonoscopy on colorectal
cancer incidence and mortality.
114 . LeClercq,C.M.C. etal. Metachronous colorectal
cancers result from missed lesions and non-
compliance with surveillance. Gastrointest. Endosc.
82, 325–333.e2 (2015).
115 . Hoff,G., Grotmol,T., Skovlund,E. & Bretthauer,M.
Risk of colorectal cancer seven years after flexible
sigmoidoscopy screening: randomised controlled trial.
BMJ 338, b1846 (2009).
116 . Atkin,W.S. etal. Once-only flexible sigmoidoscopy
screening in prevention of colorectal cancer:
amulticentre randomised controlled trial. Lancet 375,
1624–1633 (2010).
117 . Segnan,N. etal. Once-only sigmoidoscopy in
colorectal cancer screening: follow-up findings of the
Italian Randomized Controlled Trial — SCORE. J.Natl
Cancer Inst. 103, 1310–1322 (2011).
118 . VanPutten,P.G. etal. Nurse endoscopists perform
colonoscopies according to the international standard
and with high patient satisfaction. Endoscopy 44,
1127–1132 (2012).
119 . Stephens,M. etal. Non-physician endoscopists:
asystematic review. World J.Gastroenterol. 21,
5056–5071 (2015).
120. Lansdorp-Vogelaar,I., vanBallegooijen,M.,
Zauber,A.G., Habbema,J.D.F. & Kuipers,E.J. Effect
of rising chemotherapy costs on the cost savings of
colorectal cancer screening. J.Natl Cancer Inst. 101,
1412–1422 (2009).
121. Inadomi,J.M. etal. Adherence to colorectal cancer
screening: arandomized clinical trial of competing
strategies. Arch. Intern. Med. 172, 575–582 (2012).
122. VanDam,L., Kuipers,E.J., Steyerberg,E.W.,
vanLeerdam,M.E. & deBeaufort,I.D. The price of
autonomy: should we offer individuals a choice of
colorectal cancer screening strategies? Lancet Oncol.
14, e38–e46 (2013).
123. Hol,L. etal. Screening for colorectal cancer:
randomised trial comparing guaiac-based and
immunochemical faecal occult blood testing and
flexible sigmoidoscopy. Gut 59, 62–68 (2009).
124. VanRossum,L.G. etal. Random comparison of guaiac
and immunochemical fecal occult blood tests for
colorectal cancer in a screening population.
Gastroenterology 135, 82–90 (2008).
125. Wilschut,J.A. etal. Fecal occult blood testing when
colonoscopy capacity is limited. J.Natl Cancer Inst.
103, 1741–1751 (2011).
126. Quintero,E. etal. Colonoscopy versus fecal
immunochemical testing in colorectal-cancer
screening. N.Engl. J.Med. 366, 697–706 (2012).
127. Kapidzic,A. etal. Attendance and yield over three
rounds of population-based fecal immunochemical
testscreening. Am. J.Gastroenterol. 109,
1257–1264 (2014).
128. VanRoon,A.H.C. etal. Diagnostic yield improves
with collection of 2 samples in fecal immunochemical
test screening without affecting attendance.
Clin.Gastroenterol. Hepatol. 9, 333–339 (2011).
129. Goede,S.L. etal. Cost-effectiveness of one versus two
sample faecal immunochemical testing for colorectal
cancer screening. Gut 62, 727–734 (2012).
130. VanRoon,A.H.C. etal. Random comparison of
repeated faecal immunochemical testing at different
intervals for population-based colorectal cancer
screening. Gut 62, 409–415 (2012).
131. Hol,L. etal. Screening for colorectal cancer: random
comparison of guaiac and immunochemical faecal
occult blood testing at different cut-off levels.
Br.J.Cancer 100, 1103–1110 (2009).
132. VanHeijningen,E.M.B. etal. Features of adenoma
and colonoscopy associated with recurrent colorectal
neoplasia based on a large community-based study.
Gastroenterology 144, 1410–1418 (2013).
133. Lieberman,D.A. etal. Guidelines for colonoscopy
surveillance after screening and polypectomy:
aconsensus update by the US Multi-Society Task
Force on Colorectal Cancer. Gastroenterology 143,
844–857 (2012).
134. Martínez,M.E. etal. A pooled analysis of advanced
colorectal neoplasia diagnoses after colonoscopic
polypectomy. Gastroenterology 136, 832–841
(2009).
135. Løberg,M. etal. Long-term colorectal-cancer
mortality after adenoma removal. N.Engl. J.Med.
371, 799–807 (2014).
136. Hassan,C. etal. Post-polypectomy colonoscopy
surveillance: European Society of Gastrointestinal
Endoscopy (ESGE) Guideline. Endoscopy 45,
842–851 (2013).
137. Cairns,S.R. etal. Guidelines for colorectal cancer
screening and surveillance in moderate and high risk
groups. Gut 59, 666–689 (2010).
138. Lieberman,D.A. etal. Low rate of large polyps
(>9 mm) within 10years after an adequate baseline
colonoscopy with no polyps. Gastroenterology 147,
343–350 (2014).
139. Lansdorp-Vogelaar,I. etal. Personalizing age of cancer
screening cessation based on comorbid conditions:
Model estimates of harms and benefits. Ann. Intern.
Med. 161, 104–112 (2014).
140. vanHees,F. etal. Should colorectal cancer screening
be considered in elderly persons without previous
screening? Ann. Intern. Med. 160, 750–759 (2014).
PRIMER
NATURE REV IEWS
|
DISEASE PRIMERS VOLUME 1
|
2015
|
23
© 2015 Macmillan Publishers Limited. All rights reserved

141. Hazewinkel,Y. etal. Prevalence of serrated polyps and
association with synchronous advanced neoplasia in
screening colonoscopy. Endoscopy 46, 219–224
(2014).
142. IJspeert,J.E.G. etal. Development and validation of
the WASP classification system for optical diagnosis
ofadenomas, hyperplastic polyps and sessile serrated
adenomas/polyps. Gut http://dx.doi.org/10.1136/
gutjnl-2014-308411 (2015).
143. Jeffery,G.M., Hickey,B.E. & Hider,P.Follow-up
strategies for patients treated for non-metastatic
colorectal cancer. Cochrane Database Syst. Rev. 1,
CD002200 (2002).
144. Primrose,J.N. etal. Effect of 3 to 5years of
scheduled CEA and CT follow-up to detect recurrence
of colorectal cancer: the FACS randomized clinical trial.
JAMA 311, 263–270 (2014).
145. Brenner,H. etal. Progress in colorectal cancer survival
in Europe from the late 1980s to the early 21st
century: the EUROCARE study. Int. J.Cancer 131,
1649–1658 (2012).
146. Breugom,A.J. etal. Quality assurance in the
treatment of colorectal cancer: the EURECCA initiative.
Ann. Oncol. 25, 1485–1492 (2014).
147. Van de Velde,C.J.H. etal. EURECCA colorectal:
multidisciplinary management: European consensus
conference colon & rectum. Eur. J.Cancer 50,
1.e1–1.e34 (2014).
148. Van de Velde,C.J.H. etal. Experts reviews of the
multidisciplinary consensus conference colon and
rectal cancer 2012: science, opinions and experiences
from the experts of surgery. Eur. J.Surg. Oncol. 40,
454–468 (2014).
A review of the EURECCA consensus on colorectal
cancer surgery.
149. Quirke,P., West,N.P. & Nagtegaal,I.D. EURECCA
consensus conference highlights about colorectal
cancer clinical management: the pathologists expert
review. Virchows Arch. 464, 129–134 (2014).
150. Valentini,V. etal. EURECCA consensus conference
highlights about rectal cancer clinical management:
the radiation oncologist’s expert review.
Radiother.Oncol. 110 , 195–198 (2014).
151. Tudyka,V. etal. EURECCA consensus conference
highlights about colon and rectal cancer
multidisciplinary management: the radiology experts
review. Eur. J.Surg. Oncol. 40, 469–475 (2014).
152. Van de Velde,C.J.H. etal. EURECCA colorectal:
multidisciplinary mission statement on better care
forpatients with colon and rectal cancer in Europe.
Eur. J.Cancer 49, 2784–2790 (2013).
153. Rutten,H.J.T., den Dulk,M., Lemmens,V.E.,
vandeVelde,C.J.H. & Marijnen,C.A.M. Controversies
of total mesorectal excision for rectal cancer in elderly
patients. Lancet Oncol. 9, 494–501 (2008).
154. Gooiker,G.A. etal. Risk factors for excess mortality
inthe first year after curative surgery for colorectal
cancer. Ann. Surg. Oncol. 19, 2428–2434 (2012).
155. Van den Broek,C.B.M. etal. The survival gap
between middle-aged and elderly colon cancer
patients. Time trends in treatment and survival.
Eur.J.Surg. Oncol. 37, 904–912 (2011).
156. Dekker,J.W.T. etal. Cause of death the first year
after curative colorectal cancer surgery; aprolonged
impact of the surgery in elderly colorectal cancer
patients. Eur. J.Surg. Oncol. 40, 1481–1487 (2014).
157. Mulder,S.A. etal. Prevalence and prognosis of
synchronous colorectal cancer: aDutch population-
based study. Cancer Epidemiol. 35, 442–447 (2011).
158. Taylor,F.G.M. etal. Preoperative magnetic resonance
imaging assessment of circumferential resection
margin predicts disease-free survival and local
recurrence: 5-year follow-up results of the MERCURY
study. J.Clin. Oncol. 32, 34–43 (2014).
159. Veldkamp,R. etal. Laparoscopic surgery versus open
surgery for colon cancer: short-term outcomes of a
randomised trial. Lancet Oncol. 6, 477–484 (2005).
160. Bonjer,H.J. etal. A randomized trial of laparoscopic
versus open surgery for rectal cancer. N.Engl. J.Med.
372, 1324–1332 (2015).
A randomized trial with long-term follow-up,
showing similar results for open and laparoscopic
rectal cancer surgery.
161. Colon Cancer Laparoscopic or Open Resection Study
Group etal. Survival after laparoscopic surgery versus
open surgery for colon cancer: long-term outcome of a
randomised clinical trial. Lancet Oncol. 10, 44–52
(2009).
162. Chen,J. etal. Meta-analysis of temporary ileostomy
versus colostomy for colorectal anastomoses.
ActaChir. Belg. 113 , 330–339 (2013).
163. VanHooft,J.E. etal. Self-expandable metal stents for
obstructing colonic and extracolonic cancer: European
Society of Gastrointestinal Endoscopy (ESGE) Clinical
Guideline. Endoscopy 46, 990–1053 (2014).
164. Fiori,E. etal. Palliative management for patients with
subacute obstruction and stageIV unresectable
rectosigmoid cancer: colostomy versus endoscopic
stenting: final results of a prospective randomized
trial. Am. J.Surg. 204, 321–326 (2012).
165. De Graaf,E.J.R. etal. Transanal endoscopic
microsurgery versus total mesorectal excision of T1
rectal adenocarcinomas with curative intention.
Eur.J.Surg. Oncol. 35, 1280–1285 (2009).
166. Doornebosch,P.G. etal. Transanal endoscopic
microsurgery for T1 rectal cancer: size matters!
Surg.Endosc. 26, 551–557 (2011).
167. Lezoche,E. etal. Randomized clinical trial of
endoluminal locoregional resection versus
laparoscopic total mesorectal excision for T2 rectal
cancer after neoadjuvant therapy. Br. J.Surg. 99,
1211–1218 (2012).
168. Martin-Perez,B., Andrade-Ribeiro,G.D., Hunter,L.
&Atallah,S. A systematic review of transanal
minimally invasive surgery (TAMIS) from 2010 to
2013. Tech. Coloproctol. 18, 775–788 (2014).
169. Nagtegaal,I.D., Marijnen,C.A.M., Kranenbarg,E.K.,
van de Velde,C.J.H. & vanKrieken,J.H.
Circumferential margin involvement is still an
important predictor of local recurrence in rectal
carcinoma: not one millimeter but two millimeters
isthe limit. Am. J.Surg. Pathol. 26, 350–357 (2002).
170. Quirke,P. etal. Effect of the plane of surgery achieved
on local recurrence in patients with operable rectal
cancer: aprospective study using data from the MRC
CR07 and NCIC-CTG CO16 randomised clinical trial.
Lancet 373, 821–828 (2009).
171. Heald,R.J., Husband,E.M. & Ryall,R.D.
Themesorectum in rectal cancer surgery — the clue to
pelvic recurrence? Br. J.Surg. 69, 613–616 (1982).
172. Ramji,K.M. etal. Comparison of clinical and
economic outcomes between robotic, laparoscopic,
and open rectal cancer surgery: early experience at
atertiary care center. Surg. Endosc. http://dx.doi.org/
10.1007/s00464-015-4390-8 (2015).
173. Kapiteijn,E. etal. Preoperative radiotherapy
combined with total mesorectal excision for resectable
rectal cancer. N.Engl. J.Med. 345, 638–646 (2001).
174. Folkesson,J. etal. Swedish rectal cancer trial: long
lasting benefits from radiotherapy on survival and
local recurrence rate. J.Clin. Oncol. 23, 5644–5650
(2005).
175. Sebag-Montefiore,D. etal. Preoperative radiotherapy
versus selective postoperative chemoradiotherapy in
patients with rectal cancer (MRC CR07 and NCIC-CTG
C016): amulticentre, randomised trial. Lancet 373,
811–820 (2009).
176. VanGijn,W. etal. Preoperative radiotherapy
combined with total mesorectal excision for resectable
rectal cancer: 12-year follow-up of the multicentre,
randomised controlled TME trial. Lancet Oncol. 12,
575–582 (2011).
A randomized trial showing that preoperative
radiotherapy reduces local recurrence rates after
TME surgery.
177. Pettersson,D. etal. Interim analysis of the
StockholmIII trial of preoperative radiotherapy
regimens for rectal cancer. Br. J.Surg. 97, 580–587
(2010).
178. Juul,T. etal. Low anterior resection syndrome and
quality of life. Dis. Colon Rectum 57, 585–591
(2014).
179. García,M. etal. PhaseII study of preoperative
bevacizumab, capecitabine and radiotherapy for
resectable locally-advanced rectal cancer. BMC Cancer
15, 59 (2015).
180. Beyond TME Collaborative. Consensus statement on
the multidisciplinary management of patients with
recurrent and primary rectal cancer beyond total
mesorectal excision planes. Br. J.Surg. 100, E1–E33
(2013).
181. Habr-Gama,A., Perez,R.O., São Julião,G.P.,
Proscurshim,I. & Gama-Rodrigues,J. Nonoperative
approaches to rectal cancer: acritical evaluation.
Semin. Radiat. Oncol. 21, 234–239 (2011).
182. Maas,M. etal. Wait-and-see policy for clinical
complete responders after chemoradiation for rectal
cancer. J.Clin. Oncol. 29, 4633–4640 (2011).
183. Dalton,R.S.J. etal. A single-centre experience of
chemoradiotherapy for rectal cancer: is there potential
for nonoperative management? Colorectal Dis. 14,
567–571 (2012).
184. Fujita,S. etal. Postoperative morbidity and mortality
after mesorectal excision with and without lateral
lymph node dissection for clinical stageII or stageIII
lower rectal cancer (JCOG0212): results from a
multicentre, randomised controlled, non-inferiority
trial. Lancet Oncol. 13, 616–621 (2012).
185. Påhlman,L. etal. The Swedish rectal cancer registry.
Br. J.Surg. 94, 1285–1292 (2007).
186. Wibe,A. etal. Effect of hospital caseload on long-term
outcome after standardization of rectal cancer surgery
at a national level. Br. J.Surg. 92, 217–224 (2005).
187. Birkmeyer,J.D. etal. Hospital volume and surgical
mortality in the United States. N.Engl. J.Med. 346,
1128–1137 (2002).
188. Kehlet,H. Multimodal approach to control
postoperative pathophysiology and rehabilitation.
Br.J.Anaesth. 78, 606–617 (1997).
189. Kehlet,H. & Mogensen,T. Hospital stay of 2days after
open sigmoidectomy with a multimodal rehabilitation
programme. Br. J.Surg. 86, 227–230 (1999).
190. Lassen,K. etal. Consensus review of optimal
perioperative care in colorectal surgery: Enhanced
Recovery After Surgery (ERAS) Group
recommendations. Arch. Surg. 144, 961–969 (2009).
191. Boelens,P.G. etal. Reduction of postoperative ileus
by early enteral nutrition in patients undergoing major
rectal surgery. Ann. Surg. 259, 649–655 (2014).
192. Sauer,R. etal. Preoperative versus postoperative
chemoradiotherapy for rectal cancer. N.Engl. J.Med.
351, 1731–1740 (2004).
193. Glimelius,B., Tiret,E., Cervantes,A. & Arnold,D.
Rectal cancer: ESMO Clinical Practice Guidelines for
diagnosis, treatment and follow-up. Ann. Oncol. 24,
vi81–vi88 (2013).
194. Labianca,R. etal. Early colon cancer: ESMO Clinical
Practice Guidelines for diagnosis, treatment and
follow-up. Ann. Oncol. 24, vi64–vi72 (2013).
195. McCleary,N.J. etal. Impact of age on the efficacy
ofnewer adjuvant therapies in patients with stageII/III
colon cancer: findings from the ACCENT database.
J.Clin. Oncol. 31, 2600–2606 (2013).
196. Van Cutsem,E., Cervantes,A., Nordlinger,B.
&Arnold,D. Metastatic colorectal cancer: ESMO
Clinical Practice Guidelines for diagnosis, treatment
and follow-up. Ann. Oncol. 25, iii1–iii9 (2014).
European Society of Medical Oncology guidelines
for the management of metastatic colorectal cancer.
197. Amado,R.G. etal. Wild-type KRAS is required for
panitumumab efficacy in patients with metastatic
colorectal cancer. J.Clin. Oncol. 26, 1626–1634
(2008).
198. Douillard,J.-Y. etal. Panitumumab–FOLFOX4
treatment and RAS mutations in colorectal cancer.
N.Engl. J.Med. 369, 1023–1034 (2013).
199. Ferrara,N., Hillan,K.J., Gerber,H.-P. & Novotny,W.
Discovery and development of bevacizumab,
ananti-VEGF antibody for treating cancer. Nat. Rev.
Drug Discov. 3, 391–400 (2004).
200. Willett,C.G. etal. Direct evidence that the VEGF-
specific antibody bevacizumab has antivascular effects
in human rectal cancer. Nat. Med. 10, 145–147
(2004).
201. Giantonio,B.J. etal. Bevacizumab in combination
with oxaliplatin, fluorouracil, and leucovorin
(FOLFOX4) for previously treated metastatic colorectal
cancer: results from the Eastern Cooperative Oncology
Group Study E3200. J.Clin. Oncol. 25, 1539–1544
(2007).
202. Kubicka,S. etal. Bevacizumab plus chemotherapy
continued beyond first progression in patients with
metastatic colorectal cancer previously treated with
bevacizumab plus chemotherapy: ML18147 study
KRAS subgroup findings. Ann. Oncol. 24, 2342–2349
(2013).
203. Van Cutsem,E. etal. Addition of aflibercept to
fluorouracil, leucovorin, and irinotecan improves
survival in a PhaseIII randomized trial in patients with
metastatic colorectal cancer previously treated
withanoxaliplatin-based regimen. J.Clin. Oncol. 30,
3499–3506 (2012).
204. Tomlinson,J.S. etal. Actual 10-year survival after
resection of colorectal liver metastases defines cure.
J.Clin. Oncol. 25, 4575–4580 (2007).
205. Evrard,S. etal. Combined ablation and resection
(CARe) as an effective parenchymal sparing treatment
for extensive colorectal liver metastases. PLoS ONE 9,
e114404 (2014).
206. Ayez,N. etal. Outcome of microscopic incomplete
resection (R1) of colorectal liver metastases in the era
of neoadjuvant chemotherapy. Ann. Surg. Oncol. 19,
1618–1627 (2012).
PRIMER
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2015
|
VOLUME 1 www.nature.com/nrdp
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207. Falcone,A. etal. PhaseIII trial of infusional
fluorouracil, leucovorin, oxaliplatin, and irinotecan
(FOLFOXIRI) compared with infusional fluorouracil,
leucovorin, and irinotecan (FOLFIRI) as first-line
treatment for metastatic colorectal cancer:
theGruppoOncologico Nord Ovest. J.Clin. Oncol. 25,
1670–1676 (2007).
208. Heinemann,V. etal. FOLFIRI plus cetuximab versus
FOLFIRI plus bevacizumab as first-line treatment for
patients with metastatic colorectal cancer (FIRE-3):
arandomised, open-label, phase3 trial. Lancet Oncol.
15, 1065–1075 (2014).
209. Benoist,S. etal. Complete response of colorectal liver
metastases after chemotherapy: does it mean cure?
J.Clin. Oncol. 24, 3939–3945 (2006).
210. Simkens,L.H.J., Koopman,M. & Punt,C.J.A.
Optimal duration of systemic treatment in metastatic
colorectal cancer. Curr. Opin. Oncol. 26, 448–453
(2014).
211 . Grothey,A. etal. Regorafenib monotherapy for
previously treated metastatic colorectal cancer
(CORRECT): aninternational, multicentre,
randomised, placebo-controlled, phase 3 trial. Lancet
381, 303–312 (2013).
212. Smith,J.J. & Weiser,M.R. Outcomes in
non-metastatic colorectal cancer. J.Surg. Oncol. 110,
518–526 (2014).
213. Juul,T. etal. International validation of the low
anterior resection syndrome score. Ann. Surg. 259,
728–734 (2014).
214. Feddern,M.-L., Jensen,T.S. & Laurberg,S. Chronic
pain in the pelvic area or lower extremities after rectal
cancer treatment and its impact on quality of life:
apopulation-based cross-sectional study. Pain 156,
1765–1771 (2015).
215. De Caluwé,L., Van Nieuwenhove,Y. & Ceelen,W.P.
Preoperative chemoradiation versus radiation alone
for stageII and III resectable rectal cancer. Cochrane
Database Syst. Rev. 2, CD006041 (2013).
216. Bregendahl,S., Emmertsen,K.J., Lindegaard,J.C.
&Laurberg,S. Urinary and sexual dysfunction in women
after resection with and without preoperative
radiotherapy for rectal cancer: apopulation-based
cross-sectional study. Colorectal Dis. 17, 26–37 (2015).
217. Gilbert,A. etal. Systematic review of radiation
therapy toxicity reporting in randomized controlled
trials of rectal cancer: acomparison of patient-
reported outcomes and clinician toxicity reporting.
Int.J.Radiat. Oncol. Biol. Phys. 92, 555–567 (2015).
218. Diouf,M. etal. Could baseline health-related quality of
life (QoL) predict overall survival in metastatic colorectal
cancer? The results of the GERCOR OPTIMOX1 study.
Health Qual. Life Outcomes 12, 69 (2014).
219. Otto,S.J. etal. Association of change in physical
activity and body weight with quality of life and
mortality in colorectal cancer: asystematic review and
meta-analysis. Support. Care Cancer 23, 1237–1250
(2015).
220. Averyt,J.C. & Nishimoto,P.W. Psychosocial issues
incolorectal cancer survivorship: the top ten questions
patients may not be asking. J.Gastrointest. Oncol. 5,
395–400 (2014).
221. Martínez,M.E. etal. One-year risk for advanced
colorectal neoplasia: U. S. versus U. K. risk-stratification
guidelines. Ann. Intern. Med. 157, 856–864 (2012).
222. Gao,W., Gulliford,M., Bennett,M.I.,
Murtagh,F.E.M. & Higginson,I.J. Managing cancer
pain at the end of life with multiple strong opioids:
apopulation-based retrospective cohort study in
primary care. PLoS ONE 9, e79266 (2014).
223. Zhong,S. etal. Association between physical activity
and mortality in breast cancer: ameta-analysis of
cohort studies. Eur. J.Epidemiol. 29, 391–404
(2014).
224. Davies,R.J., Miller,R. & Coleman,N. Colorectal
cancer screening: prospects for molecular stool
analysis. Nat. Rev. Cancer 5, 199–209 (2005).
225. Towler,B.P., Irwig,L., Glasziou,P., Weller,D.
&Kewenter,J. Screening for colorectal cancer
usingthe faecal occult blood test, hemoccult.
CochraneDatabase Syst. Rev. 2, CD001216 (2000).
226. Brenner,H. & Tao,S. Superior diagnostic performance
of faecal immunochemical tests for haemoglobin in
ahead-to-head comparison with guaiac based faecal
occult blood test among 2235participants
ofscreening colonoscopy. Eur. J.Cancer 49,
3049–3054 (2013).
227. Schoen,R.E. etal. Colorectal-cancer incidence and
mortality with screening flexible sigmoidoscopy.
N.Engl. J.Med. 366, 2345–2357 (2012).
228. Brenner,H., Chang-Claude,J., Seiler,C.M.,
Rickert,A. & Hoffmeister,M. Protection from
colorectal cancer after colonoscopy: apopulation-
based, case–control study. Ann. Intern. Med. 154,
22–30 (2011).
229. Cash,B.D. etal. CT colonography of a medicare-aged
population: outcomes observed in an analysis of more
than 1400patients. Am. J.Roentgenol. 199, 27–34
(2012).
Author contributions
Introduction (E.J.K.); Epidemiology (T.W. and E.J.K.);
Mechanisms/pathophysiology (W.M.G.); Diagnosis, screening
and prevention (J.J.S., E.J.K. and D.L.); Management (P.G.B.,
C.J.H.v.d.V., T.S. and E.J.K.); Quality of life (E.J.K.); Outlook
(All authors); Overview of the Primer (E.J.K.).
Competing interests
T.S. has received honoraria for lectures or advisory boards
from Roche, Merck-Serono, Amgen and Bayer. All other
authors declare no competing interests.
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