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Benefits and harms of mammography screening

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Mammography screening for breast cancer is widely available in many countries. Initially praised as a universal achievement to improve women's health and to reduce the burden of breast cancer, the benefits and harms of mammography screening have been debated heatedly in the past years. This review discusses the benefits and harms of mammography screening in light of findings from randomized trials and from more recent observational studies performed in the era of modern diagnostics and treatment. The main benefit of mammography screening is reduction of breast-cancer related death. Relative reductions vary from about 15 to 25% in randomized trials to more recent estimates of 13 to 17% in meta-analyses of observational studies. Using UK population data of 2007, for 1,000 women invited to biennial mammography screening for 20 years from age 50, 2 to 3 women are prevented from dying of breast cancer. All-cause mortality is unchanged. Overdiagnosis of breast cancer is the main harm of mammography screening. Based on recent estimates from the United States, the relative amount of overdiagnosis (including ductal carcinoma in situ and invasive cancer) is 31%. This results in 15 women overdiagnosed for every 1,000 women invited to biennial mammography screening for 20 years from age 50. Women should be unpassionately informed about the benefits and harms of mammography screening using absolute effect sizes in a comprehensible fashion. In an era of limited health care resources, screening services need to be scrutinized and compared with each other with regard to effectiveness, cost-effectiveness and harms.
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REVIE W Open Access
Benefits and harms of mammography screening
Magnus Løberg
1,2,3
, Mette Lise Lousdal
4
, Michael Bretthauer
1,2,3,5
and Mette Kalager
1,3,6*
Abstract
Mammography screening for breast cancer is widely available in many countries. Initially praised as a universal
achievement to improve women's health and to reduce the burden of breast cancer, the benefits and harms of
mammography screening have been debated heatedly in the past years. This review discusses the benefits and harms
of mammography screening in light of findings from randomized trials and from more recent observational studies
performed in the era of modern diagnostics and treatment. The main benefit of mammography screening is reduction
of breast-cancer related death. Relative reductions vary from about 15 to 25% in randomized trials to more recent
estimates of 13 to 17% in meta-analyses of observational studies. Using UK population data of 2007, for 1,000 women
invited to biennial mammography screening for 20 years from age 50, 2 to 3 women are prevented from dying of
breast cancer. All-cause mortality is unchanged. Overdiagnosis of breast cancer is the main harm of mammography
screening. Based on recent estimates from the United States, the relative amount of overdiagnosis (including ductal
carcinoma in situ and invasive cancer) is 31%. This results in 15 women overdiagnosed for every 1,000 women invited
to biennial mammography screening for 20 years from age 50. Women should be unpassionately informed about the
benefits and harms of mammography screening using absolute effect sizes in a comprehensible fashion. In an era of
limited health care resources, screening services need to be scrutinized and compared with each other with regard to
effectiveness, cost-effectiveness and harms.
Introduction
The verb 'to screen' is defined as 'to sift by passing
through a screen' [1]. 'To 'sift'; derives from an old Dutch
word ('zeef'); a 'utensil consisting of a circular frame with
a finely meshed or perforated bottom, used to separate the
coarser from the finer particles of any loose material' [1].
The definitions of screening vary among different cultures,
settings, and time periods [2,3]. In general, all definitions of
screening include an identification of disease or disease pre-
cursor among presumptively healthy individuals. There are
mainly two different approaches of cancer screening: pre-
vention of disease by finding and removing premalignant
precursors of cancer; and early detection of cancer where
the goal is to treat the invasive cancer in an early curable
stage [4]. In 1968, the World Health Organization suggested
10 principles that should be fulfilled before implementing
screening in a population (Table 1) [5]. Some of the princi-
ples regard knowledge about biologic development of cancer
(principles 4 and 7).
Screening for breast cancer with mammography aims at
detecting breast cancer at an early, curable stage. For early
detection by screening to be beneficial, we anticipate a
continuous, linear growth pattern of tumors, and that
breast cancer has not spread at the time when tumors are
detectable at mammography. Thus, if the assumptions of
tumor growth are not correct or if growth of tumors is
heterogenic, screening mammography might not be an
adequate tool to reduce the burden of breast cancer [6].
The idea of early detection started in the US in the early
20
th
century with educational mass campaigns where the
message of 'do not delay' seeking medical help for a variety
of cancer signs and symptoms was central [7]. However,
none of these early campaigns had an effect on the mor-
tality of breast cancer [8]. In 1963 the first randomized
trial of mammography screening was launched within the
Health Insurance Plan in New York [8], and several other
trials followed [9]. Most of the trials were performed be-
fore widespread use of anti-estrogens and modern chemo-
therapy with the exception of the Canadian National
Breast Screening Study and the age trial [10,11].
In contrast to other cancer screening tools, mammog-
raphy screening was evaluated in randomized trials before it
was widely recommended and implemented. Nevertheless,
* Correspondence: mkalager@hsph.harvard.edu
1
Institute of Health and Society, University of Oslo, N-0317 Oslo, Norway
3
Department of Epidemiology, Harvard School of Public Health, Boston, MA
02115, USA
Full list of author information is available at the end of the article
© 2015 Løberg et al.; licensee BioMed Central. This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain
Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article,
unless otherwise stated.
Løberg et al. Breast Cancer Research (2015) 17:63
DOI 10.1186/s13058-015-0525-z
there has been a continuous discussion of mammography
screening, which started in full in 2000 after a Cochrane re-
view of the randomized trials indicated little effect of screen-
ing [12]. More recently, the effect of mammography
screening outside the experimental setting, in the modern
era with improvements in awareness, diagnostics, and treat-
ment, has been discussed [13,14].
The mammography debate has not only been about the
beneficial effects of mammography screening, but more
recently also the harms. In the last 10 years increasing
awareness of overdiagnosis in mammography screening
has emerged. Overdiagnosis is defined as the detection of
tumors at screening that might never have progressed to
become symptomatic or life-threatening in the absence of
screening. This is a direct harm of screening because
markers to distinguish the overdiagnosed tumors from the
potential life-threatening tumors are lacking and, thus, all
tumors are treated. Women with overdiagnosed tumors
only experience the harms and side effects of treatment,
without any benefit. In this review we discuss the benefits
and harms of mammography screening and give an over-
view of the findings from randomized trials and from
more recent observational studies from the era of modern
diagnostics and treatment. We aim at presenting the bene-
fits and harms per 1,000 women invited to mammography
screening who started screening at age 50 years and were
screened every second year until age 69 years; screening of
this age group has been shown to achieve most of the
benefit with less harm [15,16].
Screening mammography
Attendance rates
Mammography screening is recommended (and in Europe
offered through organized programs) in most Western
countries. However, in Switzerland an independent panel
of experts (the Swiss Medical Board) reviewed the evidence
on mammography screening and concluded that harms out-
weighed the benefits and recommended against mammog-
raphy screening [17]; that is, that screening programs
should not be implemented in areas where such programs
do not exist and that the ongoing programs should be
phased out. When screening is recommended, the eligible
age range differs in different countries from 40 to 74 years
[4,18,19]. The recommended interval between two screens
varies from 1 to 3 years [18]. Mammography screening is
well accepted; on average, more than half of eligible women
attend screening mammography. In most countries, attend-
ance rates are higher than 70%. Women aged 50 to 69 years
have the highest attendance rate [18,19]. The attendance
rate varies between countries (19.4% to 88.9%), and in differ-
ent age groups. Most women who have participated once
continue to participate.
False positive tests
As with every diagnostic test the sensitivity and spe cifi-
city of mammography scre ening are not perfe ct; various
levels of sensitivity and specificity for detecting breast
cancer have bee n published [20,21]. The risk of experi-
encing a fa lse positive mammogram for women under-
going b iennial screening from age 50 to 69 years in
Europe is a bout 20% [21], and the risk o f experiencing a
biopsyduetoafalsepositivetestis3%[21].Basedon
data from the UK , 2.3% of all women with a false posi-
tive test had a lumpe ctomy, representing 76 out of
100,000 women screened in one screening round [22].
The risk is even h igher in the US, w here the 10-year
false positive rate is 30%, and 50% of all women will ex-
perience a false positive mammogram at one time
[23,24]. The challenges w ith a false positive test , a part
from the monetary costs, are impaired psychological
well-being and changes in health behavior among
women with the false positive test. After 6 months, only
64% of those reca lled due to a false positive test were
declared cancer-free; after 1 year approximately 90%
were de clared cancer-free, and only after 2 years were
all those who were in fact free of cancer declared
cancer-free [25]. Research has s hown that false positive
results negatively influence women's psychological well-
being during the period immediately after the tests , and
a recent study showed that women with false positive
findings experience psy chological harm for at least
3 years after scre ening [26]. Women with false positive
findings had higher use of health care services; 55% of
women who experienced a positive recall returned to
the outpatient clinic in the first year after screening,
some up to eight times [27], and reported lower quality
of life t han those without [ 27,28]. Some w omen may
also have altered health behavior and trust in the health
care system [28].
Table 1 The World Health Organizations 10 principles of
screening
1. The condition sought should be an important health problem
2. There should be an accepted treatment for patients with recognized
disease
3. Facilities for diagnosis and treatment should be available
4. There should be a recognizable latent or early symptomatic stage
5. There should be a suitable test or examination
6. The test should be acceptable to the population
7. The natural history of the condition, including development from
latent to declared disease, should be adequately understood
8. There should be an agreed policy on whom to treat as patients
9. The cost of case-findings (including diagnosis and treatment of
patients diagnosed) should be economically balanced in relation to
possible expenditure on medical care as a whole
10. Case finding should be a continuing process and not a 'once and
for all' project
Løberg et al. Breast Cancer Research (2015) 17:63 Page 2 of 12
False negative tests
Inter val cancers are cancers dete cted after a normal
screening mammogram and before the next scheduled
mammogram. Interval cancers either were overlooked
at the l ast mammogram or are rapidly growing cance rs
that become apparent in the screening interval [29]. In a
re-interpretation of interval cancers, around 35% were
overlooked [30], w hile 65% were not visible at the late st
mammogram and appeared in the interval between
screening mammograms. Of all breast cancers dete cted
among women who participate in screening, 28 to 33%
are interval cancers [20], and this proportion seems to
be stable in the diffe ren t screening rounds [29 ]. Use of
digital mammography is increasing, and dete ction rates
of ductal carcinoma in situ (DCIS) and invasive cancers
are higher. Whether this w ill decrease the proportion of
inter va l cancers i s unknown, bu t the rate of missed can-
cers seems to be similar to that of analogue, screen-film
mammography [31]. One might anticipate, therefore,
that the proportion of interval cancers with digital
mammography will be comparable to that with analogue
screen-film mammography. Howe ver, the increa sing de-
tection rates with digital mammography might increase
the amount of overdiagno sis.
Women diagnosed with interval cancer do not benefit
from early detection , but could be falsely reassured by
their last normal mammogram and delay seeking med-
ical care. However, this might not seem to be the case as
women with interval cancer do not have poorer progno-
sis than women who chose not to utilize mammography
screening [ 29].
For 1,000 women invited to mammography screening
every second year for 20 years from age 50, 200 will ex-
perience a false positive mammogram, 30 will undergo a
biopsy due to a false positive mammogram, and 3 will be
diagnosed with interval cancer [32,33] (Figure 1).
Figure 1 Summary of benefits and harms when 1,000 women are screened every second years for 20 years starting at age 50. Number
of women with false positive mammograms and false positive biopsies are based on a review [32]. Number of interval cancers are based on
reported number of interval cancer in the National Health Service breast screening programme [33]. The numbers of overdiagnosed and
prevented breast cancer deaths are estimated based on 31% overdiagnosis [19] and 13 to 17% reduction in mortality from breast cancer [35].
These relative numbers are applied to the observed incidence of invasive breast cancer (women aged 50 to 69 years) and mortality (women
aged 55 to 74 years) in the UK in 2007 [32]; this resulted in 15 overdiagnosed women and 2 to 3 prevented breast cancer deaths per 1,000
women. No deaths are prevented overall [9].
Løberg et al. Breast Cancer Research (2015) 17:63 Page 3 of 12
Overdiagnosis
Mammography screening inevitably entails increased
breast cancer incidence [36] due to earlier detection of
cancers that would otherwise have been diagnosed later in
life and due to diagnosis of cancers that would not have
been identified clinically in someone's remaining lifetime.
The latter category is commonly referred to as overdiag-
nosis. Theoretically, overdiagnosis can occur because the
tumor lacks potential to progress to a clinical stage, or
even regresses [37], or because the woman dies from other
causes before the breast cancer surfaces clinically. In real-
ity, these three alternatives cannot be reliably disen-
tangled. In any of the three scenarios the individual
woman would be diagnosed and treated with no possible
survival benefit. Hence, overdiagnosis represents a sub-
stantial ethical dilemma and burdens the patient and the
health care system. Treatment for breast cancer includes
surgery, radiotherapy, chemotherapy, and antiestrogen
treatment. Risk of death from cardiovascular disease is
increased in women treated with radiotherapy [38], and
adjuvant treatment may be cardiotoxic (for example, tax-
anes, anthracyclines, or trastuzumab) [39]. It is possible
that overtreatment causes increased mortality by other
causes besides breast cancer. This may explain why there
is no reduction in measurable overall mortality with
screening mammography [9] (Figure 2).
Overdiagnosis does apply to both carcinoma in situ
and invasive cancer; the lifetime risk of progression of
carcinoma in situ to invasive breast cancer is unknown,
but probably less than 50%; [40] and the lead-time is
longer for in situ than invasive cancers. Thus, it is logical
and intuitive that carcinoma in situ can be overdiag-
nosed. However, pathological verified invasive cancers
can also be overdiagnosed. This contradicts what most
clinicians were taught in medical school, and can be
hard to understand for both clinicians and the public.
One way of looking at this challenge is by using the 'ice-
berg model' [40]: the development of cancer is a lengthy
and complex process, where unrepaired genetic instabil-
ity and changes in tumor microenvironment could lead
to distinct, heterogeneous subpopulations of abnormal
cells. Cancer can be envisioned as an iceberg of disease,
where the visible tip above the waterline comprises the
most aggressive lesions - those that produce symp toms
and clinical disease. The majority of our body of know-
ledge concerning the natural history of malignancies
Figure 2 Scenarios for different outcomes of screening mammography. (A) Screening is ineffective. (B) Screening is effective. (C) Screening
leads to overdiagnosis. (D) Screening leads to overdiagnosis that causes death from side effects of treatment.
Løberg et al. Breast Cancer Research (2015) 17:63 Page 4 of 12
comes from observations from these 'top-of-the-iceberg',
symptomatic lesions above the waterline [40]. Under-
neath the water's surface, however, there might be mul-
tiple, indole nt cancer subpopulations of cells. These
subpopulations will look like cancer to the pathologist if
detected through screening [40]. Early detection (such as
mammography screening) dives under the surface and
picks up silent lesions. The natural history of these
asymptomatic lesions has not been studied and is there-
fore essentially unknown, but many of these may be in-
dolent over time and never generate symptoms or
disease without screening.
Estimates of overdiagnosis
Precise estimation of overdiagnosis is a complicated and
difficult task. There is no perfect analysis that would be
universally applica ble to this problem. Consequently, re-
cent studies show a large variation in the estimated over-
diagnosis of breast cancer, from none to 54% [41]. In
studies based on statistical modeling to adjust for lead-
time, estimates of overdiagnosis are consistently below
5% [42,43]. In contrast, observational studies have pub-
lished higher estimates, between 22 and 54% [37,41,42],
depending on the use of the denominator [44]. In
Table 2, we presen t the amount of overdi agnosis and re-
duction in mortality estimated with different denomina-
tors (incidence/death from breast cancer in different age
groups). It clearly shows that different denominators
(rows 2 to 4 in Table 2) result in different amounts of
overdiagnosis and mortality reduction. Thus, it is im-
portant that benefits and harms of mammography
screening are presented using similar denominators (in
Table 2).
Overdiagnosis might be underestimated in the statistical
modeling studies because they tested only one assumption
at a time, based either on assumptions for the risk of pro-
gression from carcinoma in situ to invasive cancer [42], or
on sojourn time with adjustment for lead-time [42,43]. In
statistical models based on sojourn time and lead-time,
overdiagnosis has been disregarded in the estimation of
lead-time, since the assumption of growth has been based
on a progressive disease. This, however, is not the case for
overdiagnosis where the disease is non-progressive or per-
haps even regressive [37]. Thus, when using these esti-
mates, overdiagnosis is likely to be underestimated [48].
Since we do not have any direct, biological evidence of
non-progression or regression of breast cancer, assump-
tions cannot easily be tested, and represent only a 'guess'.
Evidence from observational studies is more convincing.
The difference in the estimates from observational studies
(22 to 54%) might be due to different assumptions of ex-
pected changes in breast cancer incidence due to changes
in breast cancer risk factors, different follow-up time after
introduction of screening, and differences in accounting
for lead-time. After 25 years of follow-up, the Canadian
National Breast Screening Study [10], comparing physical
breast examination with combined physical breast exam-
ination and annual mammography in women aged 40 to
59 years, found an excess of invasive cancer in the screen-
ing arm, resulting in 22% overdiagnosis. When the num-
ber of breast cancers detected at screening is used as the
denominator (as in the Canadian study), the amount of
overdiagnosis observed in the previous randomized trials
is strikingly similar (22 to 24%) [10,49] and in line with
the 30% reported in the Cochrane review of screening for
breast cancer with mammography [9]. The amount of
overdiagnosis might even be higher because DCIS, which
accounts for one out of four breast cancers detected at
mammography screening, was not included in these esti-
mates [10]. If DCIS is a precursor of invasive breast can-
cer, we would expect a drop in incidence of invasive
breast cancer after detection and removal of DCIS. There
is no evidence for this. On the contrary, incidence rates
keep increasing in countries with mammography screen-
ing [50].
Given the uncertainty of the estimates from modeling
and observational studies, we used the best available esti-
mate of overdiagnosis from observational data from a US
study where DCIS and invasive cancer were included,
follow-up was more than 25 years after screening was ini-
tiated and no extensive untestable assumptions were made
[19]. However, in the US there is no mammography
screening program, and the rate of false positives is higher
than in Europe and Australia. Thus, it might be possible
Table 2 Different percentages of overdiagnosis and mortality reduction based on the number of cancers
overdiagnosed and deaths avoided from breast cancer using different denominators (incidence/death from breast
cancer in different age-groups) in Norway in 2010
Age (years) Expected number
of cancers
Percentage of overdiagnosis
(n = 714.4)
Expected number of
breast cancer deaths
Percentage of mortality
reduction (n = 53.7)
50-99 2,208 19.4 693 7.8
50-79 1,571 27.3 506 10.6
50-69 942 45.5 334 16.1
The expected number of breast cancers and breast cancer deaths is estimated as the observed incidence and mortality rates in Norway from 1980 to 1984
multiplied by the Norweg ian female population in 2010 [45-47]. The number of overdiagnosed cancers (714.4 cancers) is based on studies by Falk and coworkers
[45] and Kalager and coworkers [44] and the number of reduced breast cancers (53.7 avoided deaths from breast cancer) is estimated by reducing the number of
expected (358) breast cancer deaths by 15% in the age group 55 to 74 years (358 × 0.15 = 53.7).
Løberg et al. Breast Cancer Research (2015) 17:63 Page 5 of 12
that the amount of overdiagnosis differs between the US
and Europe and Australia. Since none of the estimates of
overdiagnosis from Europe or Australia were based on
follow-up as long as in the US study, we choose to use the
US estimate of 31% overdiagnosis (in line with what is ob-
served in the randomized trials) [19]. We estimated the
number of overdiagnosed women based on the observed
incidence of invasive breast cancer in women aged 50 to
69 years in the UK in 2007 [19,34,49]. For 1,000 women
invited to biennial mammography screening for 20 years
from age 50, 15 will be overdiagnosed (Figure 1). Based on
different meta-analyses and reviews of benefits and harms
of mammography screening [9,22,32] and our best esti-
mate [19,34,35], we present a figure showing the different
estimates of overdiagnosis and prevented deaths from
breast cancer (Figure 3).
To be able to differentiate between potential lethal and
non-lethal cancers, experimental studies have to be per-
formed, preferably as an interdisciplinary cooperation be-
tween the biomedical and clinical communities. First,
however, one has to accept that overdiagnosis does occur,
and perhaps also change the terminology of non-lethal can-
cer to 'IDLE tumor' (InDolent Lesions of Epithelial origin),
as recently suggested [6].
Breast cancer mortality
According to the randomized breast cancer screening
trials, the relative reduction in mortality from breast
cancer ranges between 15 and 25% [9,22,36,51] for
women aged 50 to 69 years. The differences in these
estimates are due to differences in inclusion of random-
ized trials in pooled estimates. For the 25% estimated
Figure 3 Different estimates of overdiagnosed women and saved lives from breast cancer in different meta-analyses and trials.
Euroscreen: estimates derived from a review of observational studies, where estimates of mortality reduction from casecontrol studies are
included [32]. UK Independent review: estimates on relative effect derived from randomized trials of mammography screening and applied to UK
national rates for women aged 55 to 79 years [22]. UK Observational: estimates based on 31% overdiagnosis [19] and 13 to 17% reduction in
mortality from breast cancer [35] and applied to the observed incidence of invasive breast cancer (women aged 50 to 69 years) and mortality
(women aged 55 to 74 years) in the UK in 2007 [34]; this resulted in 2 to 3 prevented deaths from breast cancer. Cochrane review: estimates
from the randomized trials of mammography screening [9]. The Cochrane review does not assume the effect of mammography screening to last
for 20 years as is assumed in the other estimates, but relates to what was observed in the randomized trials [9].
Løberg et al. Breast Cancer Research (2015) 17:63 Page 6 of 12
reduction, mammo graphy screening versus no-screening
is compared; thus, the Canadian trial was not included
because they compared physical breast examination to
combined physical breast examination and annual mam-
mography [10,36]. For the 15% estimated reduction,
methodological limitations in some of the randomized
trials was accounted for [9]; without this 'adjustment', a
20% reduction was found [9,22,52]. None of the ran-
domized trials showed any effect on cancer mortality or
all-cause mortality [9]. Given the number of women
enrolled in the randomized trials (660,000) and a 20%
reduction in breast cancer mortality, a 2% reduction in
all-cause mortality should have been detectable [52].
The absence of a reduction in all-cause mortality indi-
cates that women die of other diseases at about the same
time in life with and without screening.
Study designs
There are a number of methods to investigate the effect of
mammography screening in a non-experimental setting. Co-
hort studies, casecontrol studies, and trend studies show
different estimates of mortality reduction, ranging from no
effect to 50% reduction in breast cancer mortality [53,54].
Cohort studies
The optimal non-experimental design to investigate the
effect of mammography screening is a cohort study of
women invited and women not-invited to mammography
screening who have similar baseline risk for breast cancer
and breast cancer death and similar opportunities for opti-
mal breast cancer treatment. Only few such studies exist,
and the estimated effect of mammography screening on
breast cancer mortality varies from 10 to 25% reduction
[35]. A pooled estimate of these trials showed a reduction
in breast cancer mortality of 13 to 17% [35].
Casecontrol studies
In casecontrol studies (sometimes called case-referent
studies) cases are women who die of breast cancer and con-
trols are women who are alive stratified by whether they
have undergone screening mammography or not. Thus,
these studies when performed in settings where mammog-
raphy screening is recommended or where screening pro-
grams exist are comparisons of women who participate and
who do not participate in mammography screening. The
validity of these studies is low because of healthy screenee
and self-selection bias, as women with breast cancer are not
eligible to mammography screening or to be continued to
be screened (selection of the most healthy), and women
who choose to participate in mammography screening (se-
lection) may differ with regard to risk of death from those
who do not participate [55]. Attempts to adjust for these
biases have been done by adjusting for the relative risk in
breast cancer mortality between the non-participants and
the non-invited comparison group [7,56]. The underlying
assumption of these adjustments is that we do know the risk
of uninvited women. In randomized trials, we can easily find
the risk of breast cancer death for those not invited to
mammography screening (the control group). However, in
observational studies where everybody is invited or recom-
mended to undergo mammography screening, we have to
make assumptions on risk of death from breast cancer
among the uninvited women. These assumptions cannot be
tested and are therefore based on 'best guess' estimates. In
casecontrol studies, a 50% reduction in mortality from
breast cancer is found, and similar reductions are found in
cohort studies of participants and non-participants in mam-
mography screening [54,57]. When the randomized trial
from Malmö was analyzed as a casecontrol study, a 58%
reduction in mortality from breast cancer was found,
whereas the real, observed reduction in the trial was only
4% (8% when the results were adjusted for non-compliance
and contamination) [36]. Thus, estimates from casecontrol
studies systematically overestimate the effect of screening.
Trend studies
Trend studies are studies of population-based breast cancer
mortality over time in different ages (age-standardization)
and geographic areas. Data on population-based breast can-
cer mortality are easy to retrieve, but as the yearly mortality
rate is not reflective of time of diagnosis, deaths from breast
cancer diagnosed before invitation influences the mortality
rate some years after screening is implemented. Further,
when all eligible women are invited and a screening pro-
gram has been running for some time, the mortality rate is
expected to reach a steady state and further reduction can-
not be expected. After 7 years of follow-up in the Health
Insurance Plan study, the mortality reduction was no longer
apparent [58], indicating that screening has no effect if no
longer offered. For a continuing program, however, the
mortality effect will not disappear, but reach a steady state.
Thus, in the first years after screening has been introduced
and reached full coverage in the area studied, the cause of
change in trends of breast cancer mortality can be difficult
to study and interpre t. Most trend studies show that breast
cancer mortality has declined in most European countries
since the early to mid-1990s. The decline in mortality is
even higher among women younger than the eligible age
range for screening and for some countries a reduction is
observed also for women older than the eligible age range
[59]. The interpretation of these results could be that
heightened awareness and improved therapy rather than
mammography screening are responsible for the observed
reduction [53,59,60].
Tumor stage
Another benefit of mammography screening could be
that breast cancers detected at screening are smaller and
Løberg et al. Breast Cancer Research (2015) 17:63 Page 7 of 12
thus less advanced than those detected clinically. In gen-
eral, smaller tumors are more likely to be resected by
lumpectomy, and with less node-positive disease, less
adjuvant therapy is needed. Based on the randomized
mammography screening trials, however, this is not the
case; screening wa s associated with an increase in the
number of mastectomies of about 20% [9]. The reason is
that mammography increased both the number of
women diagnosed with invasive breast cancer and the
number found to have multiple microscopic cancers dis-
tributed throughout the breast, for which mastectomy is
recommended. Further, in the National Health Service
breast screening program in the UK, 30% of DCIS and
24% of invasive breast cancers were treated with mastec-
tomy, so earlier detection does not necessarily mean less
aggressive treatment [61]. As mentioned above, another
benefit of mammography screening could be less aggres-
sive adjuvant therapy, due to smaller and less aggressive
tumors. As seen in the stage distribu tion in screening
and non-screening groups in Norway [41], screening led
to the diagnosis of 58% more stage I (localized cancer)
and 22% more stage II (regional cancer or cancer involv-
ing the lymph nodes) cancers, without any reduction in
advanced stage disease (stages III and IV). Since all these
patients receive surgery (either mastectomy or breast-
conserving surgery with radiation) and most stage II
patients are recommended to receive adjuvant chemo-
therapy, screening may have led to 58% more women
undergoing breast surgery and 22% more women under-
going adjuvant chemotherapy [41]. Thus, screening
mammography does not seem to reduce the burden of
receiving more aggressive treatment.
Cause of death
The number of women saved from brea st cancer death
might be outweighed by death from other causes due to
harms of treatment; however, d ue to uncertainty about
the overall number of women saved, we present differ-
ent estimates of women saved from brea st cancer in dif-
ferent meta-analyses of randomized and obser vational
studies of breast cancer [19,22,32,34,35] (Figu re 3 ). The
number needed to be invited to ma mmography to save
or harm women is highly dependent on the underlying
risk of brea st cancer or death from breast cancer
(Figures 4 and 5, showing risk of breast canc er and
death from breast cancer i n the US and UK [49,62]). In
theestimatesshowninFigure1,weuseUKdatafrom
2007 for mortality from breast cancer in women aged
Figure 4 Benefit and harm with screening mammography and use of aspirin over 10 years [62]. Shown are the 10-year risk of death from
breast cancer (bars above 0) and the 10-year risk of the diagnosis of breast cancer (bars below 0) among women aged 40 years and 50 years, with and
without mammography screening. Also shown are the 10-year risk of death from cancer (bar above 0) and the 10-year risk of major extracranial
bleeding, defined as bleeding necessitating transfusion or resulting in death (bar below 0), associated with the use or non-use of aspirin as a primary
preventive measure (on the basis of findings from randomized trials). In each pair (no screening versus screening and no aspirin versus aspirin), the
difference between the percentages represented by the bars shows the absolute benefit or harm associated with screening mammography or the use
of aspirin. Background data are derived from the literature.
Løberg et al. Breast Cancer Research (2015) 17:63 Page 8 of 12
55 to 74 years [34], and the relative reduction of 13 to
17% in breast cancer mortality based on a meta-analysis
of observational studies [35]. For 1,000 women invited
to mammography screening e very second year for 20
twenty years from age 50, 2 to 3 women are prevented
from dying f rom breast cancer (Figure 1).
Information to women
Screening differs from clinical practice. Individuals who
undergo a screening procedure are invited to participate
with the implied expectation that they will benefit. This
contrasts with clinical practice, where the patients ap-
proach the medical practitioner with a symptom or com-
plaint for help [3]. Thus, it is of utmost importance that
information about benefits and harms of mammography
screening is balanced. However, the harms of screening
have not been communicated to the public as well as the
benefits [63,64]. With increasing evidence of overdiagno-
sis, this is of concern and violates the individual's possi-
bility to make an informed choice.
However, proper information on risks and benefits is
not easy. Firstly, how do clinicians communicate benefits
and harms? The use of relative risks may suggest greater
effects than exist, whereas the use of absolute risks (or
equivalents, such as the number needed to screen) pre-
vents this misunderstanding. The use of relative risks
should be avoided or employed only in combination
with more comprehensible forms of communicating risk ,
such as absolute risks or numbers needed to screen [65].
Secondly, many cannot interpret numbers as well as
words and have difficulty understanding numerical
expressions of risk [66]. In medical schools, courses in
statistics usually do not go far enough in teaching statis-
tical or probabilistic thinking, and few teach strategies
for effective communication. Hence, most physicians are
poorly equipped to discuss risk factors in a way that is
readily comprehensible to their patients. This deficiency
puts the ideal of informed consent in jeopardy [65,67].
Framing is the presentation of logically equivalent infor-
mation in different forms. Positive framing emphasizes
Figure 5 Twenty year risk for diagnosis of, and death from, breast and prostate cancer with and without screening in the United Kingdom [49].
Displayed are 20-year absolute risks for incidence (including overdiagnosis) and mortality with and without screening. Overdiagnosis is set to 45% for prostate
cancer and 22% for breast cancer, respectively (age 50 to 69 years). Mortality reduction is set to be 20% for both cancers (age 55 and 74 years). For prostate
cancer, the estimates are based on the observed incidence and mortality in 1998 (before any widespread use of prostate-specific antigen (PSA)) and forbreast
cancer in 2007 (latest data available).
Løberg et al. Breast Cancer Research (2015) 17:63 Page 9 of 12
the absence of disease; negative framing emphasizes the
presence of disease [65] (Figure 6). Based on the 20-year
risk for a woman in the UK to die of breast cancer, the risk
of dying from breast cancer with mammography screening
would be 15 per 1,000 women and 17 to 18 per 1,000
women without mammography screening [49]. Positive
framing would be that the number of women that will not
die from breast cancer rises from between 982 and 983 to
985 per 1,000 women with the addition of screening for
breast cancer [34,35]. An example of positive framing is il-
lustrated in Figure 6.
Women are not only overestimating their risk of breast
cancer, but also substantially overestimating the benefit of
mammography screening [67,69-71]. Over 50% of all
women asked thought mammography screening reduced
the risk of dying from breast cancer by at least 50% [67,69].
Further, women wanted to have balanced information and
share the decision with their physician [71], but many re-
ported they were never provided information on false posi-
tives and side effects [71]. A report from Norway, where
women are invited with a prescheduled time and date of a
screening mammography appointment, showed that if the
invitation letter included an information leaflet aimed at en-
abling women to make a free and informed choice, the pre-
scheduled appointment undermined the option of not
participating [72]. The authors concluded that the current
recruitment procedures gave priority to screening uptake at
the expense of informed choice [72]. Thus, the principle of
informed choice might be in jeopardy [72].
Conclusion
Women should be correctly informed about the benefits
and harms of mammography screening (Figures 1 and 2).
A comprehensible way of communicating information on
benefits and harms of mammography screening is pre-
sented in Figure 1: among 1,000 women who start screen-
ing at age 50 and are screened for 20 years, 2 to 3 will
avoid dying from breast cancer and 200 women will have
at least one false positive test, 30 will undergo a biopsy, 3
will be diagnosed with an interval cancer, and breast can-
cer will be overdiagnosed in 15.
In an era of limited resources for health care and pre-
ventive services, we need to scrutinize our efforts in
screening and prevention. One of the overarching goals
Figure 6 Positive framing. Out of 1,000 women aged 50 to 69 years invited every second year, 781 are alive with screening and the same
number without screening over the course of 20 years. Correspondingly, 985 women and 982 to 983 women without screening will not die of
breast cancer aged 55 to 74 years. Negative framing: out of 1,000 women aged 50 to 69 years invited every second year, 204 women will die
with screening and the same number without screening. Correspondingly, 15 women with screening and 17 to 18 women without screening
will die of breast cancer between 55 and 74 years old. Number of women dying among women aged 55 to 74 years is based on the observed
mortality rates in England and Wales in 2007 [68]. The number of women dying over a 20-year period is estimated by summing the mortality
rates for the ages 55 to 74 [68].
Løberg et al. Breast Cancer Research (2015) 17:63 Page 10 of 12
of screening is the reduction of incidence or mortality of
disease. Currently, we do recommend some screening
services (such as mammography), while others are de-
bated or discouraged (such as prostate-specific antigen
screening for prostate cancer or aspirin for primary pre-
vention of cardiovascular disease and premature death).
However, as Figures 4 and 5 show, these differ ences in
recommendations do often not reflect differences in ef-
fectiveness or harms between the different tests [49,62].
Abbreviation
DCIS: Ductal carcinoma in situ.
Competing interests
MK has been the head of the Norwegian Breast Cancer Screening Program.
ML, MLL and MB declare that they have no competing interests.
Acknowledgements
The study was supported by grants from the Norwegian Cancer Society
(PhD scholarship Magnus Løberg, grant number HS02-2009-0082), US-
Norway Fulbright Foundation for Educational Exchange (Fulbright fellowship
Magnus Løberg), and Helse SorOst (Research grant Mette Kalager, grant
number 2014106).
Author details
1
Institute of Health and Society, University of Oslo, N-0317 Oslo, Norway.
2
Department of Transplantation Medicine, Oslo University Hospital, 0424
Oslo, Norway.
3
Department of Epidemiology, Harvard School of Public
Health, Boston, MA 02115, USA.
4
Department of Public Health, Aarhus
University, 8000 Aarhus C, Denmark.
5
Department of Medicine, Sorlandet
Hospital, 4604 Kristiansand, Norway.
6
Telemark Hospital, 3710 Skien, Norway.
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Løberg et al. Breast Cancer Research (2015) 17:63 Page 12 of 12
... Breast cancer is the leading cause of tumor-related deaths among women and its incidence rate is increasing[1]. Mammography is one of the most common imaging modalities for breast cancer screening, and early diagnosis plays an important role in reducing mortality rates [2][3][4]. In routine clinical work ows, the Breast Imaging Reporting and Data System (BI-RADS) published by the American College of Radiology provides standardized guidelines for mammographic reports and facilitates breast cancer risk assessment and management [5, 6]. ...
... forced BI-RADS categorization (only [1][2][3][4][5][18, 19,22] and focused on comparing the performance of current clinical criteria and BI-RADS lexicon with those of AI. However, further research is need on whether AI can serve as a supportive tool to improve clinical decision-making on routine BI-RADS categorization, e.g., easier interpretation of BI-RADS 0 and better classi cation of BI-RADS 3 and 4 groups. ...
Preprint
Full-text available
Background Recent artificial intelligence has exhibited great potential in breast imaging, but its value in precise risk stratification of mammography still needs further investigation. This study is to develop an artificial intelligence system (AIS) for accurate malignancy diagnosis and supportive decision-making on mammographic risk stratification. Methods In this retrospective study, 49732 mammograms of 24866 breasts from 12815 women from two Asian clinics between August 2012 and December 2018 were included. We developed an AIS using multi-view mammograms and multi-level convolutional neural network features to diagnosis malignancy and further assess the relative strengths of AIS versus current BI-RADS categorization. We further evaluate AIS by conducting a counterbalance-designed AI-assisted study, where ten radiologists read 1302 cases with/without AIS assistance. The area under the receiver operating characteristic curve (AUC), sensitivity, specificity, accuracy, F1 score were measured. Results The AIS yielded AUC of 0.910 to 0.995 for malignancy diagnosis in the validation and testing sets. Within BI-RADS 3–4 subgroups with pathological results, AIS can downgrade 83.1% of false-positives into benign groups, and upgrade 54.1% of false-negatives into malignant groups. Compared with BI-RADS, AIS performed better sensitivity and specificity in dense and no-calcification subgroups. AIS also can successfully assist radiologists identify 7 out of 43 malignancies initially diagnosed with BI-RADS 0 with specificity of 96.7%. In the counterbalance-designed AI-assisted study, the average AUC across 10 readers was significantly improved with AIS assistance (P = 0.001). Conclusion AIS can identify malignancy on mammography and further serve as a supportive tool for stratifying BI-RADS categorization.
... Currently, BC screening measures are mostly based on mammography, which is considered the gold standard compared to other imaging methods. However, several recent studies have linked the increase in this type of screening with greater morbidity from BC due to overdiagnosis and overtreatment 37,[43][44][45][46] . According to Tesser and d'Ávila 47 , who question the recommendation of BC screening, overdiagnosis is a hypothesis to explain the mismatch between the sustained increase in the incidence of cancers after the initiation of screenings, disproportionate to the little or no change in mortality (compared to unscreened populations) and morbidity, as there is no proportional reduction in advanced forms of cancer. ...
Article
Full-text available
Objective: To identify spatial variability of mortality from breast and cervical cancer and to assess factors associated in the city of São Paulo. Methods: Between 2009 and 2016, 10,124 deaths from breast cancer and 2,116 deaths from cervical cancer were recorded in the Mortality Information System among women aged 20 years and over. The records were geocoded by address of residence and grouped according to Primary Health Care coverage areas. A spatial regression modeling was put together using the Bayesian approach with a Besag-York-Mollié structure to verify the association of deaths with selected indicators. Results: Mortality rates from these types of cancer showed inverse spatial patterns. These variables were associated with breast cancer mortality: travel time between one and two hours to work (RR-relative risk: 0.97; 95%CI-credible interval: 0.93-1.00); women being the head of the household (RR 0.97; 95%CI 0.94-0.99) and deaths from breast cancer in private health institutions (RR 1.04; 95%CI 1.00-1.07). The following variables were associated with mortality from cervical cancer: travel time to work between half an hour and one hour (RR 0.92; 95%CI 0.87-0.98); per capita household income of up to 3 minimum wages (RR 1.27; 95%CI 1.18-1.37) and ratio of children under one year of age related to the female population aged 15 to 49 years (RR 1.09; 95%CI 1.01-1.18). Conclusion: The predicted RR for mortality from these cancers were calculated and associated with the socioeconomic conditions of the areas covered. CONFLICT OF INTERESTS: nothing to declare. HOW TO CITE THIS ARTICLE: Aguiar BS, Pellini ACG, Rebolledo EAS, Ribeiro AG, Diniz CSG, Bermudi PMM, et al. Intra-urban spatial variability of breast and cervical cancer mortality in the city of São Paulo: analysis of associated factors. Rev Bras Epidemiol. 2023; 26:e230008. https://doi.
... Currently, BC screening measures are mostly based on mammography, which is considered the gold standard compared to other imaging methods. However, several recent studies have linked the increase in this type of screening with greater morbidity from BC due to overdiagnosis and overtreatment 37,[43][44][45][46] . According to Tesser and d'Ávila 47 , who question the recommendation of BC screening, overdiagnosis is a hypothesis to explain the mismatch between the sustained increase in the incidence of cancers after the initiation of screenings, disproportionate to the little or no change in mortality (compared to unscreened populations) and morbidity, as there is no proportional reduction in advanced forms of cancer. ...
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Objective To identify spatial variability of mortality from breast and cervical cancer and to assess factors associated in the city of São Paulo. Methods Between 2009 and 2016, 10,124 deaths from breast cancer and 2,116 deaths from cervical cancer were recorded in the Mortality Information System among women aged 20 years and over. The records were geocoded by address of residence and grouped according to Primary Health Care coverage areas. A spatial regression modeling was put together using the Bayesian approach with a Besag-York-Mollié structure to verify the association of deaths with selected indicators. Results Mortality rates from these types of cancer showed inverse spatial patterns. These variables were associated with breast cancer mortality: travel time between one and two hours to work (RR – relative risk: 0.97; 95%CI – credible interval: 0.93–1.00); women being the head of the household (RR 0.97; 95%CI 0.94–0.99) and deaths from breast cancer in private health institutions (RR 1.04; 95%CI 1.00–1.07). The following variables were associated with mortality from cervical cancer: travel time to work between half an hour and one hour (RR 0.92; 95%CI 0.87–0.98); per capita household income of up to 3 minimum wages (RR 1.27; 95%CI 1.18–1.37) and ratio of children under one year of age related to the female population aged 15 to 49 years (RR 1.09; 95%CI 1.01–1.18). Conclusion The predicted RR for mortality from these cancers were calculated and associated with the socioeconomic conditions of the areas covered. Keywords: Breast neoplasm; Uterine cervical neoplasm; Mortality; Spatial regression
... Atualmente, as medidas de rastreamento do CM são baseadas majoritariamente na mamografia, considerada um exame padrão-ouro em relação a outros métodos de imagem. Contudo, diversas pesquisas recentes têm relacionado o aumento desse tipo de rastreamento com maior morbidade por CM em razão do sobrediagnóstico e sobretratamento 37,[43][44][45][46] . De acordo com Tesser e d'Ávila 47 , que questionam a recomendação do rastreamento do CM, o sobrediagnóstico é uma hipótese para explicar o descompasso entre o aumento sustentado da incidência de cânceres após o início dos rastreamentos, desproporcional à pouca ou nenhuma alteração da mortalidade (em comparação às populações não rastreadas) e da morbidade, visto que não ocorre redução proporcional das formas avançadas de câncer. ...
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Objective: To identify spatial variability of mortality from breast and cervical cancer and to assess factors associated in the city of São Paulo. Methods: Between 2009 and 2016, 10,124 deaths from breast cancer and 2,116 deaths from cervical cancer were recorded in the Mortality Information System among women aged 20 years and over. The records were geocoded by address of residence and grouped according to Primary Health Care coverage areas. A spatial regression modeling was put together using the Bayesian approach with a Besag-York-Mollié structure to verify the association of deaths with selected indicators. Results: Mortality rates from these types of cancer showed inverse spatial patterns. These variables were associated with breast cancer mortality: travel time between one and two hours to work (RR - relative risk: 0.97; 95%CI - credible interval: 0.93-1.00); women being the head of the household (RR 0.97; 95%CI 0.94-0.99) and deaths from breast cancer in private health institutions (RR 1.04; 95%CI 1.00-1.07). The following variables were associated with mortality from cervical cancer: travel time to work between half an hour and one hour (RR 0.92; 95%CI 0.87-0.98); per capita household income of up to 3 minimum wages (RR 1.27; 95%CI 1.18-1.37) and ratio of children under one year of age related to the female population aged 15 to 49 years (RR 1.09; 95%CI 1.01-1.18). Conclusion: The predicted RR for mortality from these cancers were calculated and associated with the socioeconomic conditions of the areas covered.
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Resumo Objetivou-se avaliar os impactos da COVID-19 no rastreamento do câncer de mama no Brasil. Coletaram-se dados do Sistema de Informações Ambulatoriais referentes a “mamografia bilateral para rastreamento” de janeiro/2015 a dezembro/2021. As análises foram feitas por região e para o Brasil. Calculou-se a média de exames em cada mês do ano com base nos dados de 2015 a 2019, a qual foi comparada, mensalmente, com o quantitativo de exames em 2020 e 2021, obtendo-se a diferença bruta e percentual entre esses valores. A mesma análise foi realizada para o número total de exames em 2020 e 2021, individualmente, e para os dois anos em conjunto. Em 2020 houve quedas no número de exames que variaram de 25% (Norte) a 48% (Nordeste), culminando em 1,749 milhão de exames a menos no país (queda de 44%). Em 2021, a região Centro-Oeste apresentou quantitativo de exames 11% superior ao esperado, enquanto as demais regiões apresentaram quedas entre 17% (Norte) e 27% (Sudeste/Sul), culminando em negativo de 927 mil exames no país (redução de 23%). Na análise conjunta (2020/2021), encontraram-se reduções que variaram de 11% (Centro-Oeste) a 35% (Sudeste/Sul), culminando em negativo de 2,676 milhões de procedimentos no Brasil (queda de 33%).
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... Currently, mammography screening is one of breast cancer screening method that has proven to be the most effective [4]. Breast screening using the mammography method aims to detect abnormalities in the breast that cannot be touched so that it can anticipate the continuous growth pattern of these abnormalities [5]. The development of technology today has many methods that can be used to assist medical personnel in the detection of breast cancer. ...
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Breast cancer is one of the main causes of death in women and ranks first in cancer cases in Indonesia. Therefore, an early detection and prevention of breast cancer is necessary, one of which is through mammography procedures. A machine learning classifier such as Support Vector Machines (SVM) could be used as an aid to the doctors and radiologist in diagnosing breast cancer from the mammogram images. The aim of this paper is to compare two feature extraction methods used in SVM, namely the Gray Level Co-Occurrence Matrix (GLCM) and first order with two kernels for each method, namely Gaussian and Polynomial. Classification using SVM method is carried out by testing several parameters such as the value of C, gamma, degree and varying the pixel spacing values in GLCM, which usually in previous studies only used the default pixel spacing. The dataset consists of 500 mammogram images containing 250 benign and malignant images, respectively. This study is expected to find out the best method with the highest accuracy between these two texture feature extractions and and able to distinguish between benign and malignant classes correctly. The result achieved that Gray Level Co-Occurrence Matrix (GLCM) feature extraction method with both Gaussian and Polynomial kernel yields the best performance with an accuracy of 89%.
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Liquid biopsy is currently a non-destructive and convenient method of cancer screening, due to human blood containing a variety of cancer-related biomolecules. Therefore, the development of an accurate and rapid breast cancer screening technique combined with breast cancer serum is crucial for the treatment and prognosis of breast cancer patients. In this study, the surface enhanced Raman spectroscopy (SERS) technique is used to enhance the Raman spectroscopy (RS) signal of serum based on a high sensitivity thermally annealed silver nanoparticle/porous silicon bragg mirror (AgNPs/PSB) composite substrate. Compared with RS, SERS reflects more and stronger spectral peak information, which is beneficial to discover new biomarkers of breast cancer. At the same time, to further explore the diagnostic ability of SERS technology for breast cancer. In this study, the raw spectral data are processed by baseline correction, polynomial smoothing, and normalization. Then, the relevant feature information of SERS and RS is extracted by principal component analysis (PCA), and five classification models are established to compare the diagnostic performance of SERS and RS models respectively. The experimental results show that the breast cancer diagnosis model based on the improved SERS substrate combined with the machine learning algorithm can be used to distinguish breast cancer patients from controls. The accuracy, sensitivity, specificity and AUC values of the SVM model are 100%, 100%, 100% and 100%, respectively, as well as the training time of 4ms. The above experimental results show that the SERS technology based on AgNPs/PSB composite substrate, combined with machine learning methods, has great potential in the rapid and accurate identification of breast cancer patients.
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Purpose: Studying breast and cervical cancers in space and time and verifying divergences of different territorially established socioeconomic profiles. Methods: Ecological study using spatial scanning (with socioeconomic characterization), space-time, and spatial variation of temporal trends, in order to identify significant clusters of high- and low-risk or temporal trends, of deaths from breast cancer and cervical cancer, in the city of São Paulo, Brazil, during 2000-2016. Results: High-risk spatial clusters were identified in the central areas, and low-risk clusters were identified in the peripheral areas, which were associated with better and worse socioeconomic conditions, respectively. As for cervical cancer, the pattern was the opposite. High-risk space-time clusters occurred in the early years of the study, whereas low-risk clusters occurred in the most recent years. For breast cancer, the central areas showed a temporal trend of decreasing mortality and the peripheral areas showed an increasing trend. While for cervical cancer, in general, the temporal trend was for the identified clusters to fall. Conclusion: It is expected that this study will provide insights for the formulation of public policies to implement prevention and control measures, in order to reduce mortality and inequalities related to breast and cervical cancers.
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Objective: Early detection is the most important cornerstone of breast cancer in determining treatment outcome and survival. In this study, it was aimed to investigate the level of knowledge, attitude, and practice of mammography in the early diagnosis of breast cancer in a group of women. Material and Methods: Data of this descriptive study were collected under observation with the help of a questionnaire. Female patients over 40 years of age or over 30 years of age with a family history of breast cancer admitted to our general surgery outpatient clinic for a health problem other than breast were included. Results: A total of 300 female patients with a mean age of 48.7 ± 10.9 years (min-max, 33-83 years) were included. Median frequency of correct answers among the women participating in the study was 83.7% (76.0-92.0). Mean score obtained by the participants from the questionnaire was 75.7 ± 15.8 (the median score 80; 25 th -75 th centiles, 73.3-86.7). Slightly more than half of the patients (159 patients, 53%) had at least one mammography scan before. The level of mammography knowledge was negatively correlated with age and the number of previous mammographies, and positively correlated with education level (r= -0.700, p< 0.001; r= -0.419, p< 0.001 and r= 0.643, p< 0.001, respectively). Conclusion: Although the level of knowledge about breast cancer and early diagnosis methods in women was at a satisfactory level, it is obvious that mammography screening practice of women without any breast symptoms is very low. Therefore, it should be aimed to increase women’s awareness of cancer prevention and compliance with early diagnosis methods and to promote participation in mammography screening.
Article
Mammographic screening for breast cancer demonstrably lowers mortality in women aged 50 years and older. Its efficacy for younger women is less certain, although some randomized trials do suggest benefit. Meta-analysis of previous trials has indicated a 15% drop in mortality for women 40 to 49 years of age, but this could partly be due to the inclusion of older women. The Age trial enrolled 160,921 women 39 to 41 years of age and randomly assigned them, in a 1:2 ratio, to have annual mammography up to age 48 years or to usual medical care. The results of the trial—carried out at 23 breast-screening units in the United Kingdom—were analyzed by the intention-to-treat method. Mortality rates for the two groups were compared after a mean follow-up interval of 10.7 years. Just over 80% of women attended at least one routine screen, and the number of screens for these women averaged 5.6. A nonsignificant 17% reduction in breast cancer mortality was documented in the intervention group compared to control women. The relative risk (RR) was 0.83, and the 95% confidence interval (CI), 0.66–1.04. The absolute risk reduction was 0.40 per 1000 women asked to be screened (95% CI, 0.07–0.87). When adjusting for noncompliance in screened women, mortality was reduced 24% (RR, 0.76; 95% CI, 0.51–1.01). The number of women needed to screen to prevent one death in 10 years was estimated to be 2512, a figure equivalent to approximately 17,600 invitations to be screened. The Age trial failed to demonstrate significantly reduced breast cancer mortality in women 40 to 48 years of age who were offered annual mammographic screening. It is planned to again analyze mortality rates after an average follow-up of 14 years. At present, women should be fully informed about possible unwanted effects of screening as well as the possible benefit, and also about procedural costs.
Article
The Canadian National Breast Screening Study was a randomized controlled trial that compared breast cancer incidence and mortality rates between screening mammography and physical breast examination in 89,835 women, aged 40 to 59 years. The study was initiated in 1980. The results of follow-up at 11 to 16 years were previously published. The present study compared the incidence of breast cancer and mortality up to 25 years in women aged 40 to 59 years who did or did not undergo mammography screening. Follow-up data for a mean of 22 years were obtained by center coordinators, the study’s central office, and record linkage to cancer registries and vital statistics databases. The study was conducted at 15 screening centers in six Canadian provinces, (Nova Scotia, Quebec, Ontario, Manitoba, Alberta, and British Columbia). Women aged 40 to 59 years were randomly assigned to a mammography group (1 screening every year for 5 years or control group [no mammography]). Women aged 40 to 49 years in the mammography group and all women aged 50 to 59 years in both groups received annual physical breast examinations. Women aged 40 to 49 years in the control group had a single examination followed by routine care. The primary study outcome measure was death from breast cancer. During the 5-year screening period, breast tumors were detected in 1190 women (666 in the mammography group [n = 44,925] and 524 in the control group [n = 44,910]); of these women, 180 in the mammography group and 171 in the control group died of breast cancer during the 25-year follow-up period. The 25-year cumulative mortality from breast cancers diagnosed during the screening period was similar in both groups (hazard ratio, 1.05; 95% confidence interval, 0.85–1.30; P = 0.63). There was no difference in the 25-year cumulative mortality between the women aged 40 to 49 and 50 to 59 years. During the entire 25-year study period, 3250 women in the mammography group and 3133 in the control group were diagnosed with breast cancer; of these, 500 in the mammography group and 505 in the control group died of breast cancer. Thus, the cumulative mortality rates were similar in both groups; the hazard ratio was 0.99, with a 95% confidence interval of 0.88 to 1.12, P < 0.87. During the 5-year screening period, an excess of 142 cancers were observed in the mammography group, with 106 excess cancers recorded after 15 years of follow-up. This indicates that 22% (106/484) of the cancers were overdiagnosed, representing 1 overdiagnosed breast cancer for every 424 women screened with mammography. It was concluded that annual mammography screening in women aged 40 to 59 years fails to reduce breast cancer–specific mortality compared with physical examination alone or routine care.
Article
This book presents a wealth of experience derived from improvements in UK screening over recent years and it covers all aspects of screening. The first four chapters of the book deal with concepts, methods, and evidence, explaining what screening is and how it is evaluated. Chapters five to eight describe practical aspects, for example how to make policy, and how to deliver screening to a high standard. The book includes many examples and real-life case histories, a glossary of medical terms, and each chapter concludes with a summary and self-test questions. Reference is made to the UK National Health Service, a leader in screening, but the book is internationally relevant because the principles of good screening apply in any setting. The controversies, paradoxes, uncertainties, and ethical dilemmas of screening are explained in a balanced way.
Article
Importance Patients need to consider both benefits and harms of breast cancer screening.Objective To systematically synthesize available evidence on the association of mammographic screening and clinical breast examination (CBE) at different ages and intervals with breast cancer mortality, overdiagnosis, false-positive biopsy findings, life expectancy, and quality-adjusted life expectancy.Evidence Review We searched PubMed (to March 6, 2014), CINAHL (to September 10, 2013), and PsycINFO (to September 10, 2013) for systematic reviews, randomized clinical trials (RCTs) (with no limit to publication date), and observational and modeling studies published after January 1, 2000, as well as systematic reviews of all study designs. Included studies (7 reviews, 10 RCTs, 72 observational, 1 modeling) provided evidence on the association between screening with mammography, CBE, or both and prespecified critical outcomes among women at average risk of breast cancer (no known genetic susceptibility, family history, previous breast neoplasia, or chest irradiation). We used summary estimates from existing reviews, supplemented by qualitative synthesis of studies not included in those reviews.Findings Across all ages of women at average risk, pooled estimates of association between mammography screening and mortality reduction after 13 years of follow-up were similar for 3 meta-analyses of clinical trials (UK Independent Panel: relative risk [RR], 0.80 [95% CI, 0.73-0.89]; Canadian Task Force: RR, 0.82 [95% CI, 0.74-0.94]; Cochrane: RR, 0.81 [95% CI, 0.74-0.87]); were greater in a meta-analysis of cohort studies (RR, 0.75 [95% CI, 0.69 to 0.81]); and were comparable in a modeling study (CISNET; median RR equivalent among 7 models, 0.85 [range, 0.77-0.93]). Uncertainty remains about the magnitude of associated mortality reduction in the entire US population, among women 40 to 49 years, and with annual screening compared with biennial screening. There is uncertainty about the magnitude of overdiagnosis associated with different screening strategies, attributable in part to lack of consensus on methods of estimation and the importance of ductal carcinoma in situ in overdiagnosis. For women with a first mammography screening at age 40 years, estimated 10-year cumulative risk of a false-positive biopsy result was higher (7.0% [95% CI, 6.1%-7.8%]) for annual compared with biennial (4.8% [95% CI, 4.4%-5.2%]) screening. Although 10-year probabilities of false-positive biopsy results were similar for women beginning screening at age 50 years, indirect estimates of lifetime probability of false-positive results were lower. Evidence for the relationship between screening and life expectancy and quality-adjusted life expectancy was low in quality. There was no direct evidence for any additional mortality benefit associated with the addition of CBE to mammography, but observational evidence from the United States and Canada suggested an increase in false-positive findings compared with mammography alone, with both studies finding an estimated 55 additional false-positive findings per extra breast cancer detected with the addition of CBE.Conclusions and Relevance For women of all ages at average risk, screening was associated with a reduction in breast cancer mortality of approximately 20%, although there was uncertainty about quantitative estimates of outcomes for different breast cancer screening strategies in the United States. These findings and the related uncertainty should be considered when making recommendations based on judgments about the balance of benefits and harms of breast cancer screening.
Article
A variety of estimates of the benefits and harms of mammographic screening for breast cancer have been published and national policies vary. To assess the effect of screening for breast cancer with mammography on mortality and morbidity. We searched PubMed (22 November 2012) and the World Health Organization's International Clinical Trials Registry Platform (22 November 2012). Randomised trials comparing mammographic screening with no mammographic screening. Two authors independently extracted data. Study authors were contacted for additional information. Eight eligible trials were identified. We excluded a trial because the randomisation had failed to produce comparable groups.The eligible trials included 600,000 women in the analyses in the age range 39 to 74 years. Three trials with adequate randomisation did not show a statistically significant reduction in breast cancer mortality at 13 years (relative risk (RR) 0.90, 95% confidence interval (CI) 0.79 to 1.02); four trials with suboptimal randomisation showed a significant reduction in breast cancer mortality with an RR of 0.75 (95% CI 0.67 to 0.83). The RR for all seven trials combined was 0.81 (95% CI 0.74 to 0.87). We found that breast cancer mortality was an unreliable outcome that was biased in favour of screening, mainly because of differential misclassification of cause of death. The trials with adequate randomisation did not find an effect of screening on total cancer mortality, including breast cancer, after 10 years (RR 1.02, 95% CI 0.95 to 1.10) or on all-cause mortality after 13 years (RR 0.99, 95% CI 0.95 to 1.03).Total numbers of lumpectomies and mastectomies were significantly larger in the screened groups (RR 1.31, 95% CI 1.22 to 1.42), as were number of mastectomies (RR 1.20, 95% CI 1.08 to 1.32). The use of radiotherapy was similarly increased whereas there was no difference in the use of chemotherapy (data available in only two trials). If we assume that screening reduces breast cancer mortality by 15% and that overdiagnosis and overtreatment is at 30%, it means that for every 2000 women invited for screening throughout 10 years, one will avoid dying of breast cancer and 10 healthy women, who would not have been diagnosed if there had not been screening, will be treated unnecessarily. Furthermore, more than 200 women will experience important psychological distress including anxiety and uncertainty for years because of false positive findings. To help ensure that the women are fully informed before they decide whether or not to attend screening, we have written an evidence-based leaflet for lay people that is available in several languages on www.cochrane.dk. Because of substantial advances in treatment and greater breast cancer awareness since the trials were carried out, it is likely that the absolute effect of screening today is smaller than in the trials. Recent observational studies show more overdiagnosis than in the trials and very little or no reduction in the incidence of advanced cancers with screening.