Effect of a retrograde-viewing device on adenoma detection rate during colonoscopy: the TERRACE study.
ABSTRACT Although colonoscopy is currently the optimal method for detecting colorectal polyps, some are missed. The Third Eye Retroscope provides an additional retrograde view that may detect polyps behind folds.
To determine whether the addition of the Third Eye Retroscope to colonoscopy improves the adenoma detection rate.
Prospective, multicenter, randomized, controlled trial.
Nine European and U.S. centers.
Of 448 enrolled subjects, 395 had data for 2 procedures.
Subjects underwent same-day tandem examinations with standard colonoscopy (SC) and Third Eye colonoscopy (TEC). Subjects were randomized to SC followed by TEC or TEC followed by SC.
Detection rates for all polyps and adenomas with each method.
In the per-protocol population, 173 subjects underwent SC and then TEC, and TEC yielded 78 additional polyps (48.8%), including 49 adenomas (45.8%). In 176 subjects undergoing TEC and then SC, SC yielded 31 additional polyps (19.0%), including 26 adenomas (22.6%). Net additional detection rates with TEC were 29.8% for polyps and 23.2% for adenomas. The relative risk of missing with SC compared with TEC was 2.56 for polyps (P < .001) and 1.92 for adenomas (P = .029). Mean withdrawal times for SC and TEC were 7.58 and 9.52 minutes, respectively (P < .001). The median difference in withdrawal times was 1 minute (P < .001). The mean total procedure times for SC and TEC were 16.97 and 20.87 minutes, respectively (P < .001).
Despite randomization and a large cohort, there was disparity in polyp prevalence between the 2 groups of subjects.
The Third Eye Retroscope increases adenoma detection rate by visualizing areas behind folds. (Clinical trial registration number: NCT01044732.).
- [show abstract] [hide abstract]
ABSTRACT: Gastrointestinal endoscopy is undergoing major improvements, which are driven by new available technologies and substantial refinements of optical features. In this Review, we summarize available and evolving imaging technologies that could influence the clinical algorithm of endoscopic diagnosis. Detection, characterization and confirmation are essential steps required for proper endoscopic diagnosis. Optical and nonoptical methods can help to improve each step; these improvements are likely to increase the detection rate of neoplasias and reduce unnecessary endoscopic treatments. Furthermore, functional and molecular imaging are emerging as new diagnostic tools that could provide an opportunity for personalized medicine, in which endoscopy will define disease outcome or predict the response to targeted therapy.Nature Reviews Gastroenterology & Hepatology 09/2011; 8(10):547-53. · 10.43 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Colonoscopy is considered the 'gold standard' for detection and removal of premalignant lesions in the colon. However, studies suggest that colonoscopy is less protective for right-sided than for left-sided colorectal cancer. Optimizing the effectiveness of colonoscopy is a continuous process, and during the past decade several important quality indicators have been defined that can be used to measure the performance of colonoscopy and to identify areas for quality improvement. The quality of bowel preparation can be enhanced by split-dose regimens, which are superior to single-dose regimens. Cecal intubation rates should approximate 95% and can be optimized by good technique. In selected patients, specific devices can be used to facilitate cecal intubation. Adenoma detection rates should be monitored and exceed a minimum of 25% in men and 15% in women. To this aim, optimal withdrawal technique and adequate time for inspection are of utmost importance. Of all advanced imaging techniques, chromoendoscopy is the only technique with proven benefit for adenoma detection. Finally, the technique of polypectomy affects the number of complications as well as the success of completely removing a lesion. In this Review, we provide an overview of both standard and novel colonoscopy techniques and their impact on quality indicators.Nature Reviews Gastroenterology & Hepatology 09/2011; 8(10):554-64. · 10.43 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Wave-oriented data-processing techniques, successfully applied in the past to the analysis of periodicity-induced wave phenomenologies, have been applied in the present paper to more general aperiodically ordered configurations based on two-letter substitution rules. For a representative canonical example, it has been shown that GWT configuration-spectrum phase-space processing is still capable of extracting the relevant phenomenology-matched footprints. Results also suggest that peculiar phase-space signatures can be obtained, in principle, via judicious exploitation of available geometrical and/or constitutive degrees of freedom, with interesting potential applications (e.g., radar countermeasures).Antennas and Propagation Society International Symposium, 2005 IEEE; 08/2005
Risk factors and diagnostic
strategies in colorectal cancer
Anke Maria Leufkens
A.M. Leufkens was kindly supported by an unrestricted grant from Janssen-Cilag,
Tilburg, The Netherlands
Financial support for the publication of this thesis was kindly provided by:
Dr. P. Bielderman, MD, PhD, MBA van Bielderman International Clinical Research for
Medical Devices, Dr Falk Pharma Benelux B.V., Tramedico B.V., Merck Sharp & Dohme B.V.,
Olympus Nederland B.V., Roche Nederland B.V., EuroTec B.V., Nederlandse Vereniging
voor Gastroenterologie, Zambon Nederland B.V., Afdeling Maag-, Darm- en Leverziek-
ten UMC Utrecht, Janssen-Cilag B.V, Ferring.
Copyright © Anke M. Leufkens
Barbara Bovenschen, www.buroboven.nl
Josee Driessen, www.joseedriessen.nl
Risk factors and diagnostic
strategies in colorectal cancer
Risicofactoren en diagnostische strategieën
bij colorectaal carcinoom
(met een samenvatting in het Nederlands)
ter verkrijging van de graad van doctor aan de Universiteit Utrecht
op gezag van de rector magnificus, prof. dr. van der Zwaan,
ingevolge het besluit van het college voor promoties
in het openbaar te verdedigen op
dinsdag 31 mei 2011 des middags om 2.30 uur
Anke Maria Leufkens
geboren op 24 november 1981 te Heerlen
Prof. dr. P.D. Siersema
Dr. H.B. Bueno-de-Mesquita
Dr. F.J.B. van Duijnhoven
Chapter 1 General introduction
Cigarette Smoking and colorectal cancer risk in the European
Prospective Investigation into Cancer and nutrition study
Chapter 3 Educational level and risk of colorectal cancer in EPIC with
specific reference to tumor location
Chapter 4 Biomarkers of oxidative stress and risk of developing colorectal
cancer: a cohort-nested case-control study in the EPIC study
Chapter 5 Dietary factors and outcome of colorectal cancer:
A systematic review
Diagnostic accuracy of computed tomography for colon
cancer staging: A systematic review
Chapter 7 Diffusion-weighted whole-body imaging with background body
signal suppression (DWIBS) for colorectal cancer screening:
A prospective feasibility study
Chapter 8 Effect of a retrograde-viewing device on adenoma detection
rate during colonoscopy: the TERRACE study
Chapter 9 Factors influencing miss rate of polyps in a back-to-back
Chapter 10 General discussion
Epidemiology and risk factors
Colorectal cancer (CRC) is the 3rd most prevalent cancer, which worldwide accounts
for about 1.2 million new cases and 608,000 deaths per year (1). CRC incidence varies
at least 25-fold between countries with the highest incidence rate in North-America,
Australia/New Zealand, Western Europe, and Japan (2). The incidence is lower in Africa
and Asia (2). This variation in incidence rates in different parts of the world and the
increasing incidence of CRC over the last 40 years, strongly suggests an influence of
lifestyle and environmental factors over genetic factors (2-4). Several factors are related
to an increased risk of CRC (5). Examples of dietary factors include a low fruit and
vegetable intake (6) and a low calcium and vitamin D intake (7), and a high red meat (8)
and alcohol consumption (4). Other lifestyle factors that potentially increase the risk
of CRC are smoking (9), obesity (10), a large waist circumference (11) and a low physical
Oxidative stress has also been associated with the occurrence of DNA damage and
the development of (colorectal) cancer (13;14). Oxidative stress is an imbalance between
the production of reactive oxygen species (ROS), generated by cellular processes and
several environmental factors like UV light and inflammation, and the ability to detoxify
these intermediates or to repair cellular damage. Until now, only a few prospective
studies on the etiological role of oxidative stress in CRC have been performed.
Whereas the role of dietary factors in CRC for primary prevention is extensively
investigated, the influence of dietary factors on survival and recurrence of CRC is largely
unknown. For example, CRC survivors on a Western dietary pattern, including higher
intakes of red meat and processed meats, were reported to have a higher risk of CRC
recurrence and mortality, compared to CRC survivors on a more prudent diet (15). However,
other studies have not reported such an association between pre-diagnostic meat
consumption and CRC-specific mortality (16;17). As of today, no comprehensive reviews
have been published on the potential impact of dietary habits on survivors of CRC.
Prevention and screening
Sporadic CRC develops from a benign adenomatous polyp that transforms into
an advanced adenoma with high-grade dysplasia and finally into invasive cancer
(18). Colonoscopy is still regarded as the gold standard for detection of precancerous
polyps and cancers in the colon and is currently the only method that can also remove
polyps and small early cancer in a single session (19-22). Previous research has indicated
that polypectomy results in a 76-90% reduced risk of CRC (23;24) and that screening for
adenomas is an effective way to reduce CRC mortality (25;26).
A growing number of studies, however, has documented that significant numbers of
lesions are missed during routine colonoscopy (23;24;27). Interval cancer, CRC detected after
recent colonoscopy, can originate from these missed lesions (28). Therefore, improved
methods for polyp detection are required. Miss rates of 22-28% have been reported for
polyps of all sizes and 20% for adenomas of all sizes. If adenomas are further specified
into size, miss rates are 2.1% for adenomas ≥ 10 mm, 13% for adenomas 5-10 mm, and
26% for adenomas 1-5 mm (29;30).
Reported risk factors for colonoscopic miss rates are inadequate bowel preparation,
polyp localization behind folds or in curves, size of the polyp and withdrawal time (29).
With regard to the latter, it has recently been suggested that not withdrawal time but
instead experience of the endoscopist is the main factor involved in polyp miss rates
(31). Polyp diameter and total number of polyps detected (≥3) have also been reported
to be independently associated with a lower polyp miss rate, whereas sessile or flat
polyps and location in the left colon were associated with a higher miss rate (30). Finally,
undergoing a colonoscopy in the morning and not in the afternoon has been suggested
to increase the polyp detection rate (32).
As mentioned above, an established factor influencing polyp miss rates is polyp
location in the colon. Polyps on the proximal aspect of haustral folds and rectal valves,
behind the ileocecal valve and on the inner curve of flexures are less likely to be
detected (21;29;30;33-36). The Third Eye Retroscope (Avantis Medical Systems, Inc., Sunnyvale,
CA) has been found to increase polyp and adenoma detection rate during colonoscopy
by providing a retrograde view that complements the colonoscope’s forward view
(22;37;38). In a pilot study of the Third Eye Retroscope in 24 patients (22) 11.8% additional
polyps were found behind folds that were not seen with the standard colonoscope.
Two consecutive multicenter studies reported additional detection rates with the
Third Eye Retroscope compared to the colonoscope alone of 13.2-14.8% for all polyps
and 11.0-25.0% for all adenomas (37;38).
CRC screening of average risk subjects over 50 years of age is currently advised by
the American Cancer Society, the US Multi-society Task Force on Colorectal Cancer, the
American College of Radiology (39), and by the U.S. Preventive Services Task Force (25). The
council of the European Union already advised in 2003 to start CRC screening (40) and
in 2009 the Health Council in the Netherlands advised the Dutch Minister of Health
to consider CRC screening (41). However, based on financial reasons and shortage of
endoscopy-capacity this advice has not yet been implemented (42). Screening below the
age of 50 is not recommended since the incidence of CRC is low before this age (43).
Until now, it is still not clear what the optimal method for CRC screening is since all
tests have their pros and cons. Screening tests can be divided into stool-based tests,
endoscopic screening with colonoscopy or sigmoidoscopy, and radiological imaging.
Disadvantages of stool-based tests are a relatively high number of false-positive and
false-negative results, a low sensitivity (44) and the risk of missing polyps or cancers that
do not bleed or that bleed intermittently (39). Endoscopic screening methods have the
disadvantage that they are invasive, bowel preparation is needed and there is a risk of
complications (44). Additionally, endoscopic screening would require a great endoscopy
capacity, colonoscopy is usually performed under sedation, and sigmoidoscopy does
not visualize the proximal colon (44).
Computed tomography colonography (CTC) has been suggested for CRC screening,
as it is less invasive than colonoscopy and has a low risk of complications. However,
complete bowel preparation is until now still needed, and major disadvantages of
CTC for screening purposes are the potential risks of radiation exposure and the poor
accuracy for the detection of polyps <6 mm (25;44).
A non-invasive, safe, and accurate screening method would therefore be interesting.
Diffusion-weighted imaging (DWI) is a new advanced Magnetic Resonance Imaging
(MRI) technique that allows the visualization of the random (Brownian) motion of
water molecules. Because many malignant tumors, including CRC, exhibit an impeded
diffusion, they can be highlighted using DWI, while most normal background tissue
can be suppressed (45). In Diffusion-weighted whole-body imaging with background
body signal suppression (DWIBS), image acquisition is performed under free breathing,
which allows thin slices to be obtained (typically 4-5 mm) in a very time-efficient
manner, unlike in breath-hold or respiratory-gated acquisitions (45). DWIBS has been
shown to be useful for the detection of primary tumors and metastases throughout
the body (45-48) and could therefore play a role in CRC screening. Furthermore, this
method has some advantages over current screening techniques for CRC, in that it is
non-invasive, does not require administering contrast agents or bowel preparation,
and does not use potentially harmful ionizing radiation.
When CRC is diagnosed, accurate preoperative staging is important for optimal
therapeutic planning. The Tumor Node Metastasis (TNM) classification is the worldwide
accepted system for staging of colorectal cancer (49). Accurate detection of locoregional
lymph nodes and distant metastases is most important in pre-operative staging of
patients with CRC.
Several radiological techniques have been evaluated for the staging of CRC, including
endoscopic ultrasound (EUS), MRI and Computed Tomography (CT). In the literature,
often no distinction is made between staging of CRC and cancer located in the colon
or rectum. For rectal cancer staging, the clinical value of radiological techniques has
clearly been established, particularly with regard to CT and MRI (50). In colon cancer
staging the evidence is less convincing, with most studies being retrospective or
including a relatively small number of patients (51-53). Measurement of the depth of
tumor invasion through the colonic wall and extramural extension of the tumor
(T stage), detection of metastatic spread to regional lymph nodes (N stage) and
detection of distant metastases (M stage) can all be established by CT. The quality of CT
for colon carcinoma staging is highly dependent on the oral and rectal administration
of contrast agents and the use of intra-venous contrast (54). The combined use of
scanning during arterial and venous phases improves T- and N-stage classification (55).
Treatment and survival
Several treatment options can be considered after careful staging of the disease.
Resection of the primary tumor is performed in the vast majority of patients. Resection
is also often performed in a palliative setting, particularly in case symptoms such as
rectal bleeding or (subtotal) intestinal obstruction are present or are likely to develop
in the near future. Chemotherapy as adjuvant therapy reduces the risk of cancer
relapse after surgery, and for rectal cancer neoadjuvant radiotherapy is also performed
in most cases (56). For metastatic disease in the liver resection can still be considered
and in case of advanced metastatic disease chemotherapy can improve survival (56).
There are differences in CRC survival between countries worldwide. In the Western
world 5-year survival is about 60% for colon as well as for rectum cancer (57).
OUTLINE OF THIS THESIS
The aim of this thesis is to further elucidate risk factors for the development of CRC
and survival after CRC. In addition, the role of DWIBS for CRC screening, the endoscopic
detection of polyps and adenomas with the Third Eye Retroscope, factors involved in the
miss-rate of colorectal polyps, and staging of colon cancer with CT are investigated.
This thesis discusses the role of smoking habits and socioeconomic status (SES) as risk
factors for CRC. This has been investigated in the European Prospective Investigation
into Cancer and Nutrition (EPIC), a multi-center prospective cohort study designed to
investigate the relationship between diet, nutritional and metabolic characteristics,
lifestyle factors and risk of cancer. The relationship between pre-diagnostic oxidative stress
parameters in blood and risk of developing CRC in the EPIC study is also investigated.
Cigarette smoke contains carcinogens, which are able to produce DNA changes and
may cause irreversible damage to the colorectal mucosa (58;59). In previous epidemiologic
studies, active smoking has been consistently related to an increased risk of colorectal
adenomas (60) and the relationship between smoking and an increased risk of CRC is
already largely established (61;62). However, which sub-site of the colorectum is most
sensitive to the effects of smoking is still under debate. In Chapter 2, the relationship
between smoking and subsites of CRC is further investigated.
Several previous studies have examined the relationship between socio-economic
status (SES) and CRC incidence with contradictory results (63). In general, an increased
CRC incidence among participants with low SES was reported in the US and Canada (64-
66), whereas a decreased CRC incidence among participants with low SES was observed
in Europe (67-69). In Chapter 3, we used educational level, a frequently used indicator for
SES (70), to investigate the relationship between SES and CRC.
Only a few prospective studies investigating an association between biomarkers
of oxidative stress and the development of CRC have been performed. However,
results from previous case-control studies have shown increased blood levels of
oxidative stress markers in patients with familial adenomatous polyposis (71) or CRC (72).
Whether oxidative stress has an actual causal role in carcinogenesis or whether it is
an epiphenomenon in the pathophysiological process is however under debate (13). In
Chapter 4, we investigated pre-diagnostic serum levels of oxidative stress parameters
(Reactive Oxygen Metabolites (ROM) and Ferric Reducing Ability of Plasma (FRAP)), in
relation to subsequent risk of developing CRC.
Several studies have been undertaken to investigate the influence of dietary
factors on survival and recurrence of CRC, but the results are inconclusive. In Chapter
5, we present a review of the current literature addressing this issue. We focused on
energy intake, intake of animal (meat, fish, dairy products and eggs) en plant products
(fruit, vegetables, cereals/fiber and coffee/tea), intake of vitamins (vitamin A, C, folate
and multi-vitamins) and alcohol consumption in relation to mortality, survival and
recurrence of CRC.
CT is generally considered to be the technique of choice in staging colon cancer (52;73).
In Chapter 6, we investigated the diagnostic accuracy of CT for T, N and M staging
of colon cancer patients after a diagnosis of the primary tumor and we determined
the value of CT for colon cancer staging in clinical practice by reviewing the available
Several previous studies have indicated the potential utility of DWIBS for the
detection of CRC (74-77). However, the information provided by these studies is limited
because of the retrospective inclusion of patients (and controls) and patient selection
bias. In Chapter 7, the results of a prospective study to elucidate the feasibility of
DWIBS for CRC screening are reported.
Previous studies have suggested that the retrograde view provided by the Third
Eye Retroscope improves detection of polyps on the proximal aspect of haustral folds,
rectal valves, flexures and the ileocecal valve (22;38). In Chapter 8, we report the results
of a randomized controlled trial investigating the polyp detection rate of colonoscopy
with The Third Eye Retroscope compared to colonoscopy alone.
Factors related to miss rates of polyps during colonoscopy are to some extent
undetermined. The available studies are small in number and size, heterogeneous
in design and limited in their ability to clarify which of these factors influence the
risk of a polyp being missed. In Chapter 9, we studied factors involved in miss rates of
colorectal polyps in a large prospective, same day, back-to-back colonoscopy database,
which enabled us to investigate both patient- and polyp-related factors associated
with miss rates of polyps during colonoscopy.
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