Overdiagnosis in organised mammography screening in Denmark. A comparative study

Data-driven overdiagnosis definitions: A scoping review

INTRODUCTION

Adequate methods to promptly translate digital health innovations for improved patient care are essential. Advances in Artificial Intelligence (AI) and Machine Learning (ML) have been sources of digital innovation and hold the promise to revolutionize the way we treat, manage and diagnose patients. Understanding the benefits but also the potential adverse effects of digital health innovations, particularly when these are made available or applied on healthier segments of the population is essential. One of such adverse effects is overdiagnosis.

OBJECTIVE

to comprehensively analyze quantification strategies and data-driven definitions for overdiagnosis reported in the literature.

METHODS

we conducted a scoping systematic review of manuscripts describing quantitative methods to estimate the proportion of overdiagnosed patients.

RESULTS

we identified 46 studies that met our inclusion criteria. They covered a variety of clinical conditions, primarily breast and prostate cancer. Methods to quantify overdiagnosis included both prospective and retrospective methods including randomized clinical trials, and simulations.

CONCLUSION

a variety of methods to quantify overdiagnosis have been published, producing widely diverging results. A standard method to quantify overdiagnosis is needed to allow its mitigation during the rapidly increasing development of new digital diagnostic tools.

To Consent or Not to Consent to Screening, That Is the Question

The objective of this article is to address the controversial question of whether consent is relevant for persons invited to participate in screening programs. To do so, it starts by presenting a case where the provided information historically has not been sufficient for obtaining valid informed consent for screening. Then, the article investigates some of the most relevant biases that cast doubt on the potential for satisfying standard criteria for informed consent. This may indicate that both in theory and in practice, it can be difficult to obtain valid consent for screening programs. Such an inference is profoundly worrisome, as invitees to screening programs are healthy individuals most suited to make autonomous decisions. Thus, if consent is not relevant for screening, it may not be relevant for a wide range of other health services. As such, the lack of valid consent in screening raises the question of the relevance of one of the basic ethical principles in healthcare (respect for autonomy), one of the most prominent legal norms in health legislation (informed consent), and one of the most basic tenets of liberal democracies (individual autonomy). Thus, there are good reasons to provide open, transparent, and balanced information and minimize biases in order to ascertain informed consent in screening.

Quantification of overdiagnosis in randomised trials of cancer screening: an overview and re-analysis of systematic reviews

The degree of overdiagnosis in common cancer screening trials is uncertain due to inadequate design of trials, varying definition and methods used to estimate overdiagnosis. Therefore, we aimed to quantify the risk of overdiagnosis for the most widely implemented cancer screening programmes and assess the implications of design limitations and biases in cancer screening trials on the estimates of overdiagnosis by conducting an overview and re-analysis of systematic reviews of cancer screening. We searched PubMed and the Cochrane Library from their inception dates to November 29, 2021. Eligible studies included systematic reviews of randomised trials comparing cancer screening interventions to no screening, which reported cancer incidence for both trial arms. We extracted data on study characteristics, cancer incidence and assessed the risk of bias using the Cochrane Collaboration's risk of bias tool. We included 19 trials described in 30 articles for review, reporting results for the following types of screening: mammography for breast cancer, chest X-ray or low-dose CT for lung cancer, alpha-foetoprotein and ultrasound for liver cancer, digital rectal examination, prostate-specific antigen, and transrectal ultrasound for prostate cancer, and CA-125 test and/or ultrasound for ovarian cancer. No trials on screening for melanoma were eligible. Only one trial (5%) had low risk in all bias domains, leading to a post-hoc meta-analysis, excluding trials with high risk of bias in critical domains, finding the extent of overdiagnosis ranged from 17% to 38% across cancer screening programmes. We conclude that there is a significant risk of overdiagnosis in the included randomised trials on cancer screening. We found that trials were generally not designed to estimate overdiagnosis and many trials had high risk of biases that may draw the estimates of overdiagnosis towards the null. In effect, the true extent of overdiagnosis due to cancer screening is likely underestimated.

Overdiagnosis Due to Screening Mammography for Breast Cancer among Women Aged 40 Years and Over: A Systematic Review and Meta-Analysis

The current systematic review and meta-analysis was conducted to estimate the incidence of overdiagnosis due to screening mammography for breast cancer among women aged 40 years and older. A PRISMA systematic search appraisal and meta-analysis were conducted. A systematic literature search of English publications in PubMed, Web of Science, EMBASE, Scopus, and Google Scholar was conducted without regard to the region or time period. Generic, methodological, and statistical data were extracted from the eligible studies. A meta-analysis was completed by utilizing comprehensive meta-analysis software. The effect size estimates were calculated using the fail-safe N test. The funnel plot and the Begg and Mazumdar rank correlation tests were employed to find any potential bias among the included articles. The strength of the association between two variables was assessed using Kendall’s tau. Heterogeneity was measured using the I-squared (I2) test. The literature search in the five databases yielded a total of 4214 studies. Of those, 30 articles were included in the final analysis, with sample sizes ranging from 451 to 1,429,890 women. The vast majority of the articles were retrospective cohort designs (24 articles). The age of the recruited women ranged between 40 and 89 years old. The incidence of overdiagnosis due to screening mammography for breast cancer among women aged 40 years and older was 12.6%. There was high heterogeneity among the study articles (I2 = 99.993), and the pooled event rate was 0.126 (95% CI: 15 0.101–0.156). Despite the random-effects meta-analysis showing a high degree of heterogeneity among the articles, the screening tests have to allow for a certain degree of overdiagnosis (12.6%) due to screening mammography for breast cancer among women aged 40 years and older. Furthermore, efforts should be directed toward controlling and minimizing the harmful consequences associated with breast cancer screening.

Overdiagnosis of hepatocellular carcinoma: Prevented by guidelines?

Overdiagnosis refers to detection of disease that would not otherwise become clinically apparent during a patient's lifetime. Overdiagnosis is common and has been reported for several cancer types, although there are few studies describing its prevalence in HCC surveillance programs. Overdiagnosis can have serious negative consequences including overtreatment and associated complications, financial toxicity, and psychological harms related to being labeled with a cancer diagnosis. Overdiagnosis can occur for several different reasons including inaccurate diagnostic criteria, detection of premalignant or very early malignant lesions, detection of indolent tumors, and competing risks of mortality. The risk of overdiagnosis is partly mitigated, albeit not eliminated, by several guideline recommendations, including definitions for the at-risk population in whom surveillance should be performed, surveillance modalities, surveillance interval, recall procedures, and HCC diagnostic criteria. Continued research is needed to further characterize the burden and trends of overdiagnosis as well as identify strategies to reduce overdiagnosis in the future.

Estimations of overdiagnosis in breast cancer screening vary between 0% and over 50%: why?

BACKGROUND

Published estimations of the extent of breast cancer overdiagnosis vary widely, and there have been heated debates around these estimations. Some high estimates have even been the basis of campaigns against national breast cancer screening programmes. Identifying some of the sources of heterogeneity between different estimates would help to clarify the issue.

METHODS

The simple case of neuroblastoma-a childhood cancer-screening is used to describe the basic principle of overdiagnosis estimation. The more complicated mechanism of breast cancer overdiagnosis is described based on data from Denmark, taking into account the type of data used, individual or aggregated.

FINDINGS

The type of data used in overdiagnosis studies has a meaningful effect on the estimation: no study based on individual data provides an estimate higher than 17%, while studies based on aggregated data often provide estimates higher than 40%. This is too systematic to be random. The analysis of two Danish studies, one of each kind, highlights the biases that come with the use of aggregated data and shows how they can lead to overdiagnosis.

INTERPRETATION

Many estimates of overdiagnosis associated with breast cancer screening programmes are serious overestimations.

Breast cancer screening and overdiagnosis

Overdiagnosis is a harmful consequence of screening which is particularly challenging to estimate. An unbiased setting to measure overdiagnosis in breast cancer screening requires comparative data from a screened and an unscreened cohort for at least 30 years. Such randomised data will not become available, leaving us with observational data over shorter time periods and outcomes of modelling. This collaborative effort of the International Cancer Screening Network quantified the variation in estimated breast cancer overdiagnosis in organised programmes with evaluation of both observed and simulated data, and presented examples of how modelling can provide additional insights. Reliable observational data, analysed with study design accounting for methodological pitfalls, and modelling studies with different approaches, indicate that overdiagnosis accounts for less than 10% of invasive breast cancer cases in a screening target population of women aged 50 to 69. Estimates above this level are likely to derive from inaccuracies in study design. The widely discrepant estimates of overdiagnosis reported from observational data could substantially be reduced by use of a cohort study design with at least 10 years of follow-up after screening stops. In contexts where concomitant opportunistic screening or gradual implementation of screening occurs, and data on valid comparison groups are not readily available, modelling of screening intervention becomes an advantageous option to obtain reliable estimates of breast cancer overdiagnosis.

An exploration for quantification of overdiagnosis and its effect for breast cancer screening

Objective

To redefine overdiagnosis and reestimate the proportion of overdiagnosis of breast cancer caused by screening based on the Surveillance, Epidemiology, and End Results (SEER, 1973−2015) Program data.

Methods

The breast cancer diagnosed before 1977 was defined as the no-screening cohort since America had initiated breast cancer screening from 1977. The breast cancer diagnosed in 1999 was defined as the screening cohort due to no increases in both the proportion of early-stage breast cancer until 1999 and the overall survival of early-stage breast cancer diagnosed over the three years since 1999. The magnitude of overdiagnosis was calculated as the difference in the proportions of early-stage breast cancer patients with long-time (15-year) survival to all breast cancer patients between two cohorts.

Results

Over 23 years before and after widespread screening in America, the proportion of early-stage breast cancer patients increased from 52.1% (16,891/32,443) to 72.7% (16,021/22,025) (P<0.001). The 15-year survival rate of early-stage breast cancer patients increased from 51.1% to 61.5% (P<0.001), while the proportions of early-stage breast cancer patients with long-time survival to all breast cancer patients increased from 26.6% (52.1%×51.1%) to 44.7% (72.7%×61.5%). Assuming no improvements in cancer screening technology and treatment technology, 18.1% (44.7%−26.6%) of breast cancer patients were overdiagnosed associated with screening. The age-specific overdiagnosis rates were 18.9%, 24.7%, 24.5%, 20.5%, and 8.3% for breast cancer patients aged 40−49, 50−59, 60−69, 70−74, and ≥75 years old, respectively.

Conclusions

Overdiagnosis caused by mammographic screening is probably overestimated in current screening practices. Further trials with more sophisticated designs and analyses are needed to validate our findings in the future.

Plasma MicroRNA Pair Panels as Novel Biomarkers for Detection of Early Stage Breast Cancer

Introduction: Breast cancer is the second leading cause of cancer death among females. We sought to identify microRNA (miRNA) markers in breast cancer, and determine whether miRNA expression is predictive of early stage breast cancer. The paired panel of microRNAs is promising. Methods: Global miRNA expression profiling was performed on three pooling samples of plasma from breast cancer, benign lesion and normal, using next generation sequencing technology. Thirteen microRNAs (hsa-miR-21-3p, hsa-miR-192-5p, hsa-miR-221-3p, hsa-miR-451a, hsa-miR-574-5p, hsa-miR-1273g-3p, hsa-miR-152, hsa-miR-22-3p, hsa-miR-222-3p, hsa-miR-30a-5p, hsa-miR-30e-5p, hsa-miR-324-3p, and hsa -miR-382-5p) were subsequently validated using real-time quantitative reverse transcription-polymerase chain reaction (RT-qPCR) in a cohort of 53 breast cancer, 40 benign lesions and 38 normal cases. The pairwise miRNA ratios were calculated as biomarkers to classify breast cancer. Results: According to the model used to predict breast cancer from benign lesions, a panel of five miRNA pairs had high diagnostic power with an AUC of 0.942. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of this model after 10-fold cross validation were 0.881, 0.775, 0.827, and 0.756, respectively. In addition, the other panels of miRNA pairs distinguishing the breast cancer from normal and non-cancer patients had good performance. Conclusion: Certain MicroRNA pairs were identified and deemed effective in breast cancer screening, especially when distinguishing cancer from benign lesions.

Effect of organized mammography screening on breast cancer mortality: A population-based cohort study in Norway

We aimed to estimate the effect of organized mammography screening on incidence-based breast cancer mortality by comparing changes in mortality among women eligible for screening to concurrent changes in younger and older ineligible women. In a county-wise balanced, open-cohort study, we used birth cohorts (1896-1982) to construct three age groups in both the historical and screening period: women eligible for screening, and younger or older women ineligible for screening. We included women diagnosed with breast cancer who died within the same age-period group during 1987-2010 (n = 4,903). We estimated relative incidence-based mortality rate ratios (relative MRR) comparing temporal changes in eligible women to concurrent changes in ineligible women. Additionally, we conducted analyses comparing the change in eligible women to younger, ineligible women with either continued accrual and follow-up period (eligible women only) or continued follow-up period. All three age groups experienced a reduction in mortality, but the decrease among eligible women was about the same among ineligible women (relative MRR = 1.05, 95% CI: (0.94-1.18)). Varying the definition of follow-up yielded similar results. Mammography screening was not associated with a larger breast cancer mortality reduction in women eligible relative to ineligible women.

[Discrepancies and overdiagnosis in breast cancer organized screening. A "methodology" systematic review]

BACKGROUND

The risk-benefit ratio of breast cancer organized screening is the focus of much scientific controversy, especially about overdiagnosis. The aim of this study was to relate methodological discrepancies to variations in rates of overdiagnosis to help build future decision aids and to better communicate with patients.

METHODS

A systematic review of methodology was conducted by two investigators who searched Medline and Cochrane databases from 01/01/2004 to 12/31/2016. Results were restricted to randomized controlled trials (RCTs) and observational studies in French or English that examined the question of the overdiagnosis computation.

RESULTS

Twenty-three observational studies and four RCTs were analyzed. The methods used comparisons of annual or cumulative incidence rates (age-cohort model) in populations invited to screen versus non-invited populations. Lead time and ductal carcinoma in situ (DCIS) were often taken into account. Some studies used statistical modeling based on the natural history of breast cancer and gradual screening implementation. Adjustments for lead time lowered the rate of overdiagnosis. Rate discrepancies, ranging from 1 to 15 % for some authors and around 30 % for others, could be explained by the hypotheses accepted concerning very slow growing tumors or tumors that regress spontaneously.

CONCLUSION

Apparently, research has to be centered on the natural history of breast cancer in order to provide responses concerning the questions raised by the overdiagnosis controversy.

As you like it: How the same data can support manifold views of overdiagnosis in breast cancer screening

Overdiagnosis estimates have varied substantially, causing confusion. The discussions have been complicated by the fact that population and study design have varied substantially between studies. To help assess the impact of study design choices on the estimates, we compared them on a single population. A cohort study from Funen County, Denmark, recently suggested little (∼1%) overdiagnosis. It followed previously screened women for up to 14 years after screening had ended. Using publically available data from Funen, we recreated the designs from five high-estimate, highly cited studies from various countries. Selected studies estimated overdiagnosis to be 25-54%. Their designs were adapted only to the extent that they reflect the start of screening in Funen in 1993. The reanalysis of the Funen data resulted in overdiagnosis estimates that were remarkably similar to those from the original high-estimate age-period studies, 21-55%. In additional analyses, undertaken to elucidate the effect of the individual components of the study designs, overdiagnosis estimates were more than halved after the most likely changes in the background risk were accounted for and decreased additionally when never-screened birth cohorts were excluded from the analysis. The same data give both low and high estimates of overdiagnosis, it all depends on the study design. This stresses the need for a careful scrutiny of the validity of the assumptions underpinning the estimates. Age-period analyses of breast cancer overdiagnosis suggesting very high frequencies of overdiagnosis rested on unmet assumptions. This study showed that overdiagnosis estimates should in the future be requested to adequately control for the background risk and include an informative selection of the studied population to achieve valid and comparable estimates of overdiagnosis.

Outcome of breast cancer screening in Denmark

BACKGROUND

In Denmark, national roll-out of a population-based, screening mammography program took place in 2007-2010. We report on outcome of the first four biennial invitation rounds.

METHODS

Data on screening outcome were retrieved from the 2015 and 2016 national screening quality reports. We calculated coverage by examination; participation after invitation; detection-, interval cancer- and false-positive rates; cancer characteristics; sensitivity and specificity, for Denmark and for the five regions.

RESULTS

At the national level coverage by examination remained at 75-77%; lower in the Capital Region than in the rest of Denmrk. Detection rate was slightly below 1% at first screen, 0.6% at subsequent screens, and one region had some fluctuation over time. Ductal carcinoma in situ (DCIS) constituted 13-14% of screen-detected cancers. In subsequent rounds, 80% of screen-detected invasive cancers were node negative and 40% ≤10 mm. False-positive rate was around 2%; higher for North Denmark Region than for the rest of Denmark. Three out of 10 breast cancers in screened women were diagnosed as interval cancers.

CONCLUSIONS

High coverage by examination and low interval cancer rate are required for screening to decrease breast cancer mortality. Two pioneer local screening programs starting in the 1990s were followed by a decrease in breast cancer mortality of 22-25%. Coverage by examination and interval cancer rate of the national program were on the favorable side of values from the pioneer programs. It appears that the implementation of a national screening program in Denmark has been successful, though regional variations need further evaluation to assure optimization of the program.

Mammography screening: A major issue in medicine

Breast cancer mortality is declining in most high-income countries. The role of mammography screening in these declines is much debated. Screening impacts cancer mortality through decreasing the incidence of number of advanced cancers with poor prognosis, while therapies and patient management impact cancer mortality through decreasing the fatality of cancers. The effectiveness of cancer screening is the ability of a screening method to curb the incidence of advanced cancers in populations. Methods for evaluating cancer screening effectiveness are based on the monitoring of age-adjusted incidence rates of advanced cancers that should decrease after the introduction of screening. Likewise, cancer-specific mortality rates should decline more rapidly in areas with screening than in areas without or with lower levels of screening but where patient management is similar. These two criteria have provided evidence that screening for colorectal and cervical cancer contributes to decreasing the mortality associated with these two cancers. In contrast, screening for neuroblastoma in children was discontinued in the early 2000s because these two criteria were not met. In addition, overdiagnosis - i.e. the detection of non-progressing occult neuroblastoma that would not have been life-threatening during the subject's lifetime - is a major undesirable consequence of screening. Accumulating epidemiological data show that in populations where mammography screening has been widespread for a long time, there has been no or only a modest decline in the incidence of advanced cancers, including that of de novo metastatic (stage IV) cancers at diagnosis. Moreover, breast cancer mortality reductions are similar in areas with early introduction and high penetration of screening and in areas with late introduction and low penetration of screening. Overdiagnosis is commonplace, representing 20% or more of all breast cancers among women invited to screening and 30-50% of screen-detected cancers. Overdiagnosis leads to overtreatment and inflicts considerable physical, psychological and economic harm on many women. Overdiagnosis has also exerted considerable disruptive effects on the interpretation of clinical outcomes expressed in percentages (instead of rates) or as overall survival (instead of mortality rates or stage-specific survival). Rates of radical mastectomies have not decreased following the introduction of screening and keep rising in some countries (e.g. the United States of America (USA)). Hence, the epidemiological picture of mammography screening closely resembles that of screening for neuroblastoma. Reappraisals of Swedish mammography trials demonstrate that the design and statistical analysis of these trials were different from those of all trials on screening for cancers other than breast cancer. We found compelling indications that these trials overestimated reductions in breast cancer mortality associated with screening, in part because of the statistical analyses themselves, in part because of improved therapies and underreporting of breast cancer as the underlying cause of death in screening groups. In this regard, Swedish trials should publish the stage-specific breast cancer mortality rates for the screening and control groups separately. Results of the Greater New York Health Insurance Plan trial are biased because of the underreporting of breast cancer cases and deaths that occurred in women who did not participate in screening. After 17 years of follow-up, the United Kingdom (UK) Age Trial showed no benefit from mammography screening starting at age 39-41. Until around 2005, most proponents of breast screening backed the monitoring of changes in advanced cancer incidence and comparative studies on breast cancer mortality for the evaluation of breast screening effectiveness. However, in an attempt to mitigate the contradictions between results of mammography trials and population data, breast-screening proponents have elected to change the criteria for the evaluation of cancer screening effectiveness, giving precedence to incidence-based mortality (IBM) and case-control studies. But practically all IBM studies on mammography screening have a strong ecological component in their design. The two IBM studies done in Norway that meet all methodological requirements do not document significant reductions in breast cancer mortality associated with mammography screening. Because of their propensity to exaggerate the health benefits of screening, case-control studies may demonstrate that mammography screening could reduce the risk of death from diseases other than breast cancer. Numerous statistical model approaches have been conducted for estimating the contributions of screening and of patient management to reductions in breast cancer mortality. Unverified assumptions are needed for running these models. For instance, many models assume that if screening had not occurred, the majority of screen-detected asymptomatic cancers would have progressed to symptomatic advanced cancers. This assumption is not grounded in evidence because a large proportion of screen-detected breast cancers represent overdiagnosis and hence non-progressing tumours. The accumulation of population data in well-screened populations diminishes the relevance of model approaches. The comparison of the performance of different screening modalities - e.g. mammography, digital mammography, ultrasonography, magnetic resonance imaging (MRI), three-dimensional tomosynthesis (TDT) - concentrates on detection rates, which is the ability of a technique to detect more cancers than other techniques. However, a greater detection rate tells little about the capacity to prevent interval and advanced cancers and could just reflect additional overdiagnosis. Studies based on the incidence of advanced cancers and on the evaluation of overdiagnosis should be conducted before marketing new breast-imaging technologies. Women at high risk of breast cancer (i.e. 30% lifetime risk and more), such as women with BRCA1/2 mutations, require a close breast surveillance. MRI is the preferred imaging method until more radical risk-reduction options are eventually adopted. For women with an intermediate risk of breast cancer (i.e. 10-29% lifetime risk), including women with extremely dense breast at mammography, there is no evidence that more frequent mammography screening or screening with other modalities actually reduces the risk of breast cancer death. A plethora of epidemiological data shows that, since 1985, progress in the management of breast cancer patients has led to marked reductions in stage-specific breast cancer mortality, even for patients with disseminated disease (i.e. stage IV cancer) at diagnosis. In contrast, the epidemiological data point to a marginal contribution of mammography screening in the decline in breast cancer mortality. Moreover, the more effective the treatments, the less favourable are the harm-benefit balance of screening mammography. New, effective methods for breast screening are needed, as well as research on risk-based screening strategies.

Quantifying Overdiagnosis in Cancer Screening: A Systematic Review to Evaluate the Methodology

Background

Overdiagnosis is the main harm of cancer screening programs but is difficult to quantify. This review aims to evaluate existing approaches to estimate the magnitude of overdiagnosis in cancer screening in order to gain insight into the strengths and limitations of these approaches and to provide researchers with guidance to obtain reliable estimates of overdiagnosis in cancer screening.

Methods

A systematic review was done of primary research studies in PubMed that were published before January 1, 2016, and quantified overdiagnosis in breast cancer screening. The studies meeting inclusion criteria were then categorized by their methods to adjust for lead time and to obtain an unscreened reference population. For each approach, we provide an overview of the data required, assumptions made, limitations, and strengths.

Results

A total of 442 studies were identified in the initial search. Forty studies met the inclusion criteria for the qualitative review. We grouped the approaches to adjust for lead time in two main categories: the lead time approach and the excess incidence approach. The lead time approach was further subdivided into the mean lead time approach, lead time distribution approach, and natural history modeling. The excess incidence approach was subdivided into the cumulative incidence approach and early vs late-stage cancer approach. The approaches used to obtain an unscreened reference population were grouped into the following categories: control group of a randomized controlled trial, nonattenders, control region, extrapolation of a prescreening trend, uninvited groups, adjustment for the effect of screening, and natural history modeling.

Conclusions

Each approach to adjust for lead time and obtain an unscreened reference population has its own strengths and limitations, which should be taken into consideration when estimating overdiagnosis.

Overdiagnosis in breast cancer screening: The impact of study design and calculations

Overdiagnosis in breast cancer screening is an important issue. A recent study from Denmark concluded that one in three breast cancers diagnosed in screening areas in women aged 50-69 years were overdiagnosed. The purpose of this short communication was to disentangle the study's methodology in order to evaluate the soundness of this conclusion. We found that both the use of absolute differences as opposed to ratios; the sole focus on non-advanced tumours and the crude allocation of tumours and person-years by screening history for women aged 70-84 years, all contributed to the very high estimate of overdiagnosis. Screening affects cohorts of screened women. Danish registers allow very accurate mapping of the fate of every woman. We should be past the phase where studies of overdiagnosis are based on the fixed age groups from routine statistics.

Differentiating clinical care from disease prevention: a prerequisite for practicing quaternary prevention

This article contends that the distinction between clinical care (illness) and prevention of future disease is essential to the practice of quaternary prevention. The authors argue that the ongoing entanglement of clinical care and prevention transforms healthy into "sick" people through changes in disease classification criteria and/or cut-off points for defining high-risk states. This diverts health care resources away from those in need of care and increases the risk of iatrogenic harm in healthy people. The distinction in focus is based on: (a) management of uncertainty (more flexible when caring for ill persons); (b) guarantee of benefit (required only in prevention); (c) harm tolerance (nil or minimal in prevention). This implies attitudinal differences in the decision-making process: greater skepticism, scientism and resistance towards preventive action. These should be based on high-quality scientific evidence of end-outcomes that displays a net positive harm/benefit ratio.

Harms of Breast Cancer Screening: Systematic Review to Update the 2009 U.S. Preventive Services Task Force Recommendation

BACKGROUND

In 2009, the U.S. Preventive Services Task Force recommended biennial mammography screening for women aged 50 to 74 years and selective screening for those aged 40 to 49 years.

PURPOSE

To review studies of screening in average-risk women with mammography, magnetic resonance imaging, or ultrasonography that reported on false-positive results, overdiagnosis, anxiety, pain, and radiation exposure.

DATA SOURCES

MEDLINE and Cochrane databases through December 2014.

STUDY SELECTION

English-language systematic reviews, randomized trials, and observational studies of screening.

DATA EXTRACTION

Investigators extracted and confirmed data from studies and dual-rated study quality. Discrepancies were resolved through consensus.

DATA SYNTHESIS

Based on 2 studies of U.S. data, 10-year cumulative rates of false-positive mammography results and biopsies were higher with annual than biennial screening (61% vs. 42% and 7% vs. 5%, respectively) and for women aged 40 to 49 years, those with dense breasts, and those using combination hormone therapy. Twenty-nine studies using different methods reported overdiagnosis rates of 0% to 54%; rates from randomized trials were 11% to 22%. Women with false-positive results reported more anxiety, distress, and breast cancer-specific worry, although results varied across 80 observational studies. Thirty-nine observational studies indicated that some women reported pain during mammography (1% to 77%); of these, 11% to 46% declined future screening. Models estimated 2 to 11 screening-related deaths from radiation-induced cancer per 100,000 women using digital mammography, depending on age and screening interval. Five observational studies of tomosynthesis and mammography indicated increased biopsies but reduced recalls compared with mammography alone.

LIMITATIONS

Studies of overdiagnosis were highly heterogeneous, and estimates varied depending on the analytic approach. Studies of anxiety and pain used different outcome measures. Radiation exposure was based on models.

CONCLUSION

False-positive results are common and are higher for annual screening, younger women, and women with dense breasts. Although overdiagnosis, anxiety, pain, and radiation exposure may cause harm, their effects on individual women are difficult to estimate and vary widely.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality.

Risk of non-sentinel node metastases in patients with symptomatic cancers compared to screen-detected breast cancers

BACKGROUND

Symptomatic breast cancers may be more aggressive as compared to screen-detected breast cancers. This could favor axillary lymph node dissection (ALND) in patients with symptomatic breast cancer and positive sentinel nodes.

METHOD

We identified 955 patients registered in the Danish Breast Cancer Cooperative Group (DBCG) Database in 2008 - 2010 with micrometastases (773) or isolated tumor cells (ITC) (182) in the sentinel node. Patients were cross-checked in the Danish Quality Database of Mammography Screening and 481 patients were identified as screen-detected cancers. The remaining 474 patients were considered as having symptomatic cancers. Multivariate analyses of the risk of non-sentinel node metastases were performed including known risk factors for non-sentinel node metastases as well as method of detection.

RESULTS

18% of the patients had metastases in non-sentinel nodes. This was evenly distributed between patients with symptomatic and screen-detected cancers; 18.5% vs 17.5% (OR 1.07; 95% CI 0.77-1.49; p = 0.69). In patients with micrometastases 21% had non-sentinel node metastases in the group with symptomatic cancers compared to 19% of patients with screen-detected cancers. This difference was not significant (OR 1.16; 95% CI 0.81-1.65, p = 0.43). Neither the multivariate analysis showed an increased risk of non-sentinel node metastases in patients with symptomatic cancers compared to screen-detected cancers (OR 1.12, CI 0.77-1.62, p = 0.55). In patients with ITCs 8% of patients with symptomatic cancers had non-sentinel node metastases compared to 13% of patients with screen-detected cancers. This difference was not significant (OR 0.58; 95% CI 0.22-1.54, p = 0.27). In the multivariate analysis, the risk of non-sentinel node metastases was still not significantly increased in patients with symptomatic cancers compared to screen-detected cancers (OR 0.45; 95% CI 0.16-1.27, p = 0.13).

CONCLUSION

We did not find any clinically relevant difference in the risk of non-sentinel node metastases between patients with symptomatic and screen-detected cancers with micrometastases or ITC in the sentinel node.

International Variation in Female Breast Cancer Incidence and Mortality Rates

BACKGROUND

Breast cancer is the most frequently diagnosed cancer and the leading cause of cancer-related death among women worldwide. Herein, we examine global trends in female breast cancer rates using the most up-to-date data available.

METHODS

Breast cancer incidence and mortality estimates were obtained from GLOBOCAN 2012 (globocan.iarc.fr). We analyzed trends from 1993 onward using incidence data from 39 countries from the International Agency for Research on Cancer and mortality data from 57 countries from the World Health Organization.

RESULTS

Of 32 countries with incidence and mortality data, rates in the recent period diverged-with incidence increasing and mortality decreasing-in nine countries mainly in Northern/Western Europe. Both incidence and mortality decreased in France, Israel, Italy, Norway, and Spain. In contrast, incidence and death rates both increased in Colombia, Ecuador, and Japan. Death rates also increased in Brazil, Egypt, Guatemala, Kuwait, Mauritius, Mexico, and Moldova.

CONCLUSIONS

Breast cancer mortality rates are decreasing in most high-income countries, despite increasing or stable incidence rates. In contrast and of concern are the increasing incidence and mortality rates in a number of countries, particularly those undergoing rapid changes in human development. Wide variations in breast cancer rates and trends reflect differences in patterns of risk factors and access to and availability of early detection and timely treatment.

IMPACT

Increased awareness about breast cancer and the benefits of early detection and improved access to treatment must be prioritized to successfully implement breast cancer control programs, particularly in transitioning countries.

Overdiagnosis: epidemiologic concepts and estimation

Overdiagnosis of thyroid cancer was propounded regarding the rapidly increasing incidence in South Korea. Overdiagnosis is defined as 'the detection of cancers that would never have been found were it not for the screening test', and may be an extreme form of lead bias due to indolent cancers, as is inevitable when conducting a cancer screening programme. Because it is solely an epidemiological concept, it can be estimated indirectly by phenomena such as a lack of compensatory drop in post-screening periods, or discrepancies between incidence and mortality. The erstwhile trials for quantifying the overdiagnosis in screening mammography were reviewed in order to secure the data needed to establish its prevalence in South Korea.

Women's Experiences With Mammography Screening Through 6 Years of Participation--A Longitudinal Qualitative Study

In this article we explore women's experiences with 6 years of mammography screening. Regular and repeated mammography screening is promoted as an important tool for disease prevention among women worldwide. The purpose of the present study was to explore how continued participation in screening influences how women perceive screening and breast cancer. We carried out focus groups with 24 screening participants in 2003 and 2009. Our analysis highlights that while women were excited about the examination in 2003, it was perceived as routine in 2009. Waiting for the results became easier over the years, while stress related to receiving the results letter did not diminish. Knowledge of risk factors for breast cancer did not change. Personal risk assessment remained low, though high incidence of cancer among acquaintances suggested high risk for breast cancer among women in general. Analysis of participant experiences suggests that continuous participation in screening has led surveillance medicine to become a part of ordinary life.

Quantifying and monitoring overdiagnosis in cancer screening: a systematic review of methods

OBJECTIVE

To determine the optimal method for quantifying and monitoring overdiagnosis in cancer screening over time.

DESIGN

Systematic review of primary research studies of any design that quantified overdiagnosis from screening for nine types of cancer. We used explicit criteria to critically appraise individual studies and assess strength of the body of evidence for each study design (double blinded review), and assessed the potential for each study design to accurately quantify and monitor overdiagnosis over time.

DATA SOURCES

PubMed and Embase up to 28 February 2014; hand searching of systematic reviews.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

English language studies of any design that quantified overdiagnosis for any of nine common cancers (prostate, breast, lung, colorectal, melanoma, bladder, renal, thyroid, and uterine); excluded case series, case reports, and reviews that only reported results of other studies.

RESULTS

52 studies met the inclusion criteria. We grouped studies into four methodological categories: (1) follow-up of a well designed randomized controlled trial (n=3), which has low risk of bias but may not be generalizable and is not suitable for monitoring; (2) pathological or imaging studies (n=8), drawing conclusions about overdiagnosis by examining biological characteristics of cancers, a simple design limited by the uncertain assumption that the measured characteristics are highly correlated with disease progression; (3) modeling studies (n=21), which can be done in a shorter time frame but require complex mathematical equations simulating the natural course of screen detected cancer, the fundamental unknown question; and (4) ecological and cohort studies (n=20), which are suitable for monitoring over time but are limited by a lack of agreed standards, by variable data quality, by inadequate follow-up time, and by the potential for population level confounders. Some ecological and cohort studies, however, have addressed these potential weaknesses in reasonable ways.

CONCLUSIONS

Well conducted ecological and cohort studies in multiple settings are the most appropriate approach for quantifying and monitoring overdiagnosis in cancer screening programs. To support this work, we need internationally agreed standards for ecological and cohort studies and a multinational team of unbiased researchers to perform ongoing analysis.

A telephone reminder intervention to improve breast screening information and access

OBJECTIVES

In the UK, women aged 50-70 are offered breast cancer screening every three years. Screening participation rates in London have been particularly low. Low rates have been associated with low socio-economic status, and some ethnic groups have been observed to be underserved by cancer screening. This paper reports on a telephone reminder intervention in London Newham, an area of high deprivation and ethnic diversity.

STUDY DESIGN

Observational study of planned intervention.

METHODS

Women invited for breast screening were telephoned to confirm receipt of the invitation letter, remind invitees of their upcoming appointment, and to provide further information. Aggregate data at general practice level on invitation to and attendance at breast screening and on numbers reached by telephone were analysed by logistic regression.

RESULTS

For the 29 participating GP practices (10,928 invitees) overall uptake in 2010 was higher compared to the previous screening round in 2007 (67% vs. 51%; p < 0.001). On average 59% of invitees were reached by the reminder calls. A 10% increase in women reached resulted in an 8% increase in the odds of women attending their screening appointment (95% CI: 5%-11%), after adjusting for 2007 attendance rates. Practices with a higher proportion of South Asian women were associated with a larger uptake adjusted for 2007 uptake and population reached by the telephone intervention, (4% increase in odds of attendance per 10% increase in South Asian population, CI 1%-7%, p = 0.003) while practices with a higher proportion of black women were associated with a smaller uptake similarly adjusted. (11% decrease in odds of attendance per 10% increase in black population, CI 9%-16%, p < 0.001).

CONCLUSIONS

A language- and culture-sensitive programme of reminder calls substantially improved breast cancer screening uptake.

Communicating the benefits and harms of colorectal cancer screening needed for an informed choice: a systematic evaluation of leaflets and booklets

OBJECTIVE

Evidence-based health information (EBHI) can support informed choice regarding whether or not to attend colorectal cancer (CRC) screening. The present study aimed to assess if German leaflets and booklets appropriately inform consumers on the benefits and harms of CRC screening.

METHODS

A systematic search for print media on CRC screening was performed via email enquiry and internet search. The identified documents were assessed for the presence and correctness of information on benefits and harms by two reviewers independently using a comprehensive list of criteria.

RESULTS

Many of the 28 leaflets and 13 booklets identified presented unbalanced information on the benefits and harms of CRC screening: one-third did not provide any information on harms. Numeracy information was often lacking. Ten cross-language examples of common misinterpretations or basically false and misleading information were identified.

DISCUSSION

Most of the CRC screening leaflets and booklets in Germany do not meet current EBHI standards. After the study, the publishers of the information materials were provided feedback, including a discussion of our findings. The results can be used to revise existing information materials or to develop new materials that provide correct, balanced, quantified, understandable and unbiased information on CRC screening.

European transnational ecological deprivation index and participation in population-based breast cancer screening programmes in France

BACKGROUND

We investigated factors explaining low breast cancer screening programme (BCSP) attendance taking into account a European transnational ecological Deprivation Index.

PATIENTS AND METHODS

Data of 13,565 women aged 51-74years old invited to attend an organised mammography screening session between 2010 and 2011 in thirteen French departments were randomly selected. Information on the women's participation in BCSP, their individual characteristics and the characteristics of their area of residence were recorded and analysed in a multilevel model.

RESULTS

Between 2010 and 2012, 7121 (52.5%) women of the studied population had their mammography examination after they received the invitation. Women living in the most deprived neighbourhood were less likely than those living in the most affluent neighbourhood to participate in BCSP (OR 95%CI=0.84[0.78-0.92]) as were those living in rural areas compared with those living in urban areas (OR 95%CI=0.87[0.80-0.95]). Being self-employed (p<0.0001) or living more than 15min away from an accredited screening centre (p=0.02) was also a barrier to participation in BCSP.

CONCLUSION

Despite the classless delivery of BCSP, inequalities in uptake remain. To take advantage of prevention and to avoid exacerbating disparities in cancer mortality, BCSP should be adapted to women's personal and contextual characteristics.

Medical ethics and screening: on what evidence should we support ourselves?

 If screening had been a drug, it would have been withdrawn from the market. Thus, which country will be first to stop mammography screening? (Peter C. Gøtzsche) 1This issue of RBMFC addresses the subject of medical ethics, the backbone that should guide both the demands in health services and health technologies provision, as well as the practice of family and community physicians. As a stimulus for reflection, the Debate section tackles the “Preventive mandatory mammography” policy in Uruguay, while in the Section Essays, Jamoulle and Gomez discuss the concept of quaternary prevention: action that aims to offer ethically acceptable alternatives to patients in order to prevent the excess of medical interventions.2 Despite considerable technological and social transformations that directly affect people’s health, ethics in medicine continues to morally shape health problems and health policy decisions with implications for patients, physicians and health institutions.In a practical analytical and easy to understand guidance for health professionals, Gillon3 discusses the four principles and scope of medical ethics: autonomy, beneficence, non-maleficence and justice. The latter encompasses the distributive justice, individual right justice and legal justice. These four principles provide a baseline for dialogue across different cultures, religious beliefs and political positions, as these principles are considered to be prima facie: a duty which is compulsory on all occasions unless it is in conflict with equal or stronger duties.4 Thus, based on these four principles that underlie ethics in medicine and consequently the application of the quaternary prevention, cancer screening programme will be critically analysed as a preventative strategy.Screening programmes entails the use of an initial selective tool or a sieve phase (i.e. mammography) to separate asymptomatic persons within the target population, that will need to undergo a classificatory or diagnostic phase - which involves a ‘gold standard’ for defining a disease (i.e. anatomopathology) – to finally offer patients a definitive preventive treatment for the condition screened.5 Since this type of intervention is performed on healthy individuals, the ethical requirements in the cases of screening programmes are very high, because the risks of damage are not balanced against real suffering (a clinically manifested disease), but are anchored in a potential future of illness and death. In this case, the principle of non-maleficence (do not harm) prevails over the principle of beneficence (the desire to promote the patients’ wellbeing), since asymptomatic persons, who perceive themselves as healthy, may have their health perception shaken indefinitely due to a biomedical intervention. The most often cited damages in the literature are psychological (due to the uncertainties of false positives, false assurance of false negatives, and borderline conditions that require a closer monitoring such as Cervical Intraepithelial Neoplasia - CIN I, II, III), as well as the physical consequences resulting from treatment itself, such as impotence or urinary incontinence, in the case of screening and treatment of prostate cancer.Since in the screening and/or health check ups the intervention is usually a ‘mirage-guided’ or ‘probability-guided’, it can result in ‘damage without the potential benefits’,6 as in the case of invasive procedures (to clarify ‘images’ or ‘positive’ exam results produced in the selective or sieving phase) which can result in complications, but the biopsy turnout to be normal. For instance, colonoscopy, laparoscopy, biopsies (liver, kidney, prostate), in which those procedures may end up producing complications (intestinal perforation, anaesthesia complications, major artery perforation, sepsis) with the potential to scale up into hospital readmission, with stress for patients and families and/or an even worse scenario: patients’ death with a benign finding. Therefore, screening programmes intrinsically carry the potential to convert healthy people into sick individuals at the population level, and consequently are highly iatrogenic and could be summarized as follows: “For many are called, but few are chosen…,” but many will need to suffer for to very few be cured.This is particularly true in the case of breast cancer screening with mammography, which renders physiopathologically insignificant cancers (overdiagnosis) exposing previously healthy women to significant damages due to radiotherapy. Gotzsche et al.7 highlighted important risks of adverse effects as consequence of radiotherapy, such as heart failure (27%) from circulatory cardiac damage and/or induction of lung cancer (78%). Furthermore, a recently published systematic review in the British Medical Journal8 on the adverse effects of cancer screening, found that only a third of randomized controlled clinical trials was concerned in measuring and controlling for potential harms of screening intervention. This article is very important because it has a direct effect upon the practice of health professionals, who cannot address security parameters on cancer screening interventions with their patients, since there is an information selection bias that emphasizes only the positive aspects of screening, for lack of controlling and monitoring of potential harms in most screening clinical trials.From an ethical stance, this context of uncertainty undermines the patients’ autonomy, creating false empowerment, since women do not have a more complete view on the potential harms and benefits of breast cancer screening programmes.9 To truly empower women and strengthen their autonomy for deciding upon interventions that directly affect their health, there is a need for information to be more transparent and also to reveal potential harms of the interventions. Moreover, the language used for the dissemination of information should be neutral, of simple understanding, culturally accessible, so that the users of the health system can better decide about their own health.3From the perspective of public health, distributive ethic justice, and limited healthcare budget - that any health system faces - screening programmes diverts financial resources - which should primarily be allocated to the treatment and care of sick individuals - towards healthy people, with the potential to produce new real patients, due to the damage of the interventions on healthy bodies, generating more costs to the health system and society in general.Fortunately, screening programmes are increasingly losing their strength, especially in Europe. For instance, the Swiss Medical Board10 found no scientific rational for the maintenance of breast screening programmes in light of current available scientific evidence. In Denmark, the rate of mortality attributable to breast cancer have not reduced due to the implementation of systematic breast cancer screening programme with mammography over 17 years follow up,11 however, it has produced an overdiagnosis rate of 33%.12 Similar trends in mortality over the last 30 years were also observed in the United States,13 as well as in Canada, the accumulated 25 years monitoring of the effects of breast cancer screening, did not render reduction in mortality from breast cancer, but resulted in 22% of overdiagnosis.14 Thus, to Peter C. Gotzsche,1 one of the world ‘s leading authorities on the subject, the best method we have to reduce the occurrence of breast cancer is to stop screening with mammography.From an ethical and scientific point of view,10 screening programmes should be discontinued or restricted to high-risk groups or very specific situations, and the focus of prevention should be redirected towards interventions on early-symptomatic patients, since breast cancer treatment has improved considerably in recent decades, and this is likely to be the responsible for improving the quality of life of affected women.1 The Canadian Task Force15 on preventive health care in their last update (2011) regarded as weak recommendation the breast cancer screening with mammography every 2-3 years in age group 50-69 years-old, because they considered the evidence for screening only of moderate quality. The Brazilian Ministry of Health16 also acted correctly in limiting the financial incentives for breast cancer screening for the age group 50-69 years.Therefore, ‘there is nothing wrong saying no to mammography’,9 because when acting upon asymptomatic healthy people, the principle of non-maleficence should override the principle of beneficence. Thus, the challenge left for family and community doctors is to individualize each case in this ‘sea of uncertainty’, sharing with their patients the often hidden potential harms attributed to cancer screening in order to operationalize in daily practice the concept of quaternary prevention.

Ética médica e rastreamento: em quais evidências deveríamos nos apoiar?

 Se o rastreamento fosse uma droga, ela já teria sido retirada do mercado. Assim, qual será o primeiro país a parar com as mamografias para rastreamento de câncer de mama?(Peter C. Gøtzsche) 1Nesta edição a RBMFC discute o tema da ética médica, espinha dorsal que orienta tanto as demandas por serviços ou tecnologias em saúde, como a prática dos médicos de família e comunidade. Como estímulo à essa reflexão, a seção Debate discute a “mamografia-obrigatória preventiva” no Uruguai, enquanto que na seção Ensaios, Jamoulle e Gomez discorrem sobre o conceito de prevenção quaternária, ação que tem como objetivo oferecer alternativas eticamente aceitáveis aos usuários, de modo a prevenir o excesso de intervenções médicas.2 Portanto, apesar das consideráveis transformações tecnológicas e sociais que afetam diretamente a saúde das pessoas, a ética em medicina continua a formatar moralmente as decisões e problemas em saúde, com implicações para pacientes, médicos e instituições de saúde.Como guia analítico prático e de fácil compreensão para os profissionais da saúde, Gillon3 discute os quatro princípios e o escopo da ética médica: autonomia, beneficência, não-maleficência e justiça. Esta última se divide em justiça distributiva, justiça com base no direito e justiça legal. Esses quatro princípios fornecem um patamar de diálogo para diferentes culturas, crenças religiosas e posicionamentos políticos, visto que estes princípios são considerados prima facie: constituem dever que se impõe em todas as ocasiões em que se atua sobre a saúde das pessoas, a menos que haja um conflito entre deveres iguais ou mais fortes que estes.4 Assim, com base nesses quatro princípios que fundamentam a ética em medicina e, consequentemente, a aplicação da prevenção quaternária, pretende-se analisar criticamente o rastreamento do câncer de mama, enquanto medida preventiva.Os programas organizados de rastreamento têm por princípio a utilização de um instrumento inicial de seleção ou peneiramento (i.e. mamografia) para separar pessoas assintomáticas na população-alvo, que necessitarão ser classificadas ou diagnosticadas por meio de um ‘gold-standard’ que define a doença (i.e. anatomopatológico) para, então, ser oferecido à pessoa o tratamento preventivo definitivo para a condição rastreada.5 Como esse tipo de intervenção recai sobre indivíduos saudáveis, os requerimentos éticos nos casos dos programas de rastreamento são altíssimos, pois os riscos de danos não estão contrabalançados com um sofrimento real (doença já instalada), mas sim, estão ancorados em um potencial futuro de adoecimento e morte. Neste caso, o princípio da não-maleficência (não causar danos) impera sobre o da beneficência (desejo de promover o bem-estar dos pacientes), visto que pessoas assintomáticas, que se percebem como saudáveis, podem ter sua saúde abalada indefinidamente devido a intervenção da biomedicina. Os exemplos de danos mais citados na literatura são sofrimentos psicológicos (devido as incertezas dos falsos positivos, falsa segurança dos falsos negativos e das situações limítrofes, que requerem monitoramento de perto, como as Neoplasias Intra-epiteliais Cervicais – NIC I, II, III), bem como as sequelas físicas resultantes dos tratamentos, tais como impotência ou incontinência urinária, no caso do rastreamento e tratamento do câncer de próstata.Como no rastreamento e/ou check up a intervenção é orientada com base em uma ‘miragem’ ou probabilidade, este pode resultar em ‘danos sem potenciais benefícios’,6 em que os procedimentos invasivos (para esclarecer ‘imagens’ ou resultados de exames ‘positivamente’ suspeitos na fase de seleção ou peneiramento) resultam em complicações, porém a biópsia resulta normal. Por exemplo, as colonoscopias, laparoscopias, biópsias (de fígado, rim, próstata), podem produzir complicações (perfuração de alça intestinal, complicação na anestesia, perfuração de artéria importante, sepses) podendo escalonar para readmissão hospitalar, com estresse para pacientes e familiares e/ou em um pior cenário, morte do paciente com um laudo de anatomopatológico benigno. Portanto, os programas de rastreamento, por converterem pessoas saudáveis em enfermos em uma escala populacional, são altamente iatrogênicos, podendo ser resumidos na seguinte frase: “muito serão chamados, poucos os escolhidos...”, mas muitos serão prejudicados para que pouquíssimos sejam ‘curados’.Isso é particularmente verdadeiro no caso do rastreamento do câncer de mama, que produz canceres fisiopatologicamente insignificantes (sobrediagnóstico) expondo mulheres previamente saudáveis a danos significativos devido ao tratamento com radioterapia. Gøtzsche et al.7 alertam para os riscos de efeitos adversos importantes da irradiação, tais como insuficiência cardíaca (27%) por dano da circulação cardíaca e/ou indução de câncer de pulmão (78%). Além do mais, uma revisão sistemática recentemente publicada no British Medical Journal8 sobre os efeitos adversos dos rastreamentos de cânceres em geral, verificou que somente um terço dos ensaios clínicos controlados aleatorizados se preocupou em medir os danos da intervenção do rastreamento. Esse artigo é importante porque afeta diretamente a prática dos profissionais para estabelecer os parâmetros de segurança da intervenção junto a seus pacientes, visto que existe um viés de seleção de informação que ressalta apenas os aspectos positivos do rastreamento, deixando de controlar e/ou monitorar potenciais danos.Do ponto de vista ético, esse contexto de incerteza fere a autonomia das pacientes, criando muita vezes um falso empoderamento, uma vez que as mulheres não detém uma visão mais completa sobre os potenciais riscos e benefícios dos programas de rastreamento do câncer de mama.9 Para realmente empoderar a mulher, de modo a fortalecer sua autonomia para decidir sobre as intervenções que afetam sua saúde, há a necessidade de que a informação seja mais transparente e que revele também os potenciais danos da intervenção. Além disso, a linguagem usada na divulgação da informação deve ser neutra, de simples entendimento, culturalmente acessível, de modo que as usuárias do sistema de saúde possam decidir melhor sobre sua saúde.3Do ponto de vista da saúde pública, da ética da justiça distributiva, e dos limitados recursos em saúde que qualquer sistema de saúde enfrenta, os programas de rastreamento desviam recursos financeiros - que deveriam ser prioritariamente investidos no tratamento e cuidado das pessoas doentes - para as pessoas saudáveis, com o agravo de produzir novos doentes reais, fruto do dano da intervenção sobre corpos saudáveis, gerando mais custos para o sistema de saúde e para a sociedade em geral.Felizmente, os programas de rastreamento estão cada vez mais perdendo sua força, principalmente na Europa, a exemplo do Swiss Medical Board10 que não encontrou razão para a manutenção dos programas de rastreamento do câncer de mama, em face das novas evidências científicas. Na Dinamarca a taxa de mortalidade atribuída ao câncer de mama não foi reduzida devido a implementação do rastreamento sistemático do câncer de mama com mamografias, ao longo de 17 anos de seguimento,11 entretanto, se produziu uma taxa de sobrediagnóstico de 33%.12 Resultados semelhantes também foram encontrados nos Estados Unidos após 30 anos de observação13, e no Canadá, o acumulado de 25 anos de acompanhamento dos efeitos do rastreamento do câncer de mama, além de não representar redução da mortalidade por câncer de mama, resultou em 22% de sobrediagnósticos.14 Assim, para Peter C. Gøtzsche,1 umas das maiores autoridades mundiais sobre o tema, o melhor método que dispomos para reduzir a ocorrência do câncer de mama é parar com o seu rastreamento por meio de mamografias.Desse modo, tanto do ponto de vista ético como científico,10 os programas de rastreamento deveriam ser descontinuados ou se restringirem a grupos ou situações muito específicas, e o foco da prevenção ser redirecionado para a intervenção no sintomático-precoce, visto que o tratamento do câncer de mama melhorou consideravelmente nas últimas décadas, sendo este o provável responsável pela melhoria da qualidade de vida das mulheres afetadas.1 A Força Tarefa Canadense15 de cuidados preventivos em saúde, em sua mais recente atualização (em 2011) avaliou como fraca a recomendação para o rastreamento do câncer de mama com mamografia a cada 2 a 3 anos na faixa etária de 50 a 69 anos, pois as evidências para o rastreio foram consideradas apenas de moderada qualidade. Assim, o Ministério da Saúde16 brasileiro agiu de forma bem fundamentada ao restringir os incentivos financeiros ao rastreamento do câncer de mama à faixa etária de 50 a 69 anos.Portanto, ‘não há nada de errado em dizer não à mamografia’,9 pois, ao se atuar sobre pessoas assintomáticas e saudáveis, o princípio da não-maleficência deve sobrepor-se ao da beneficência. O desafio posto aos médicos de família e comunidade é o de individualizar cada caso neste mar de incertezas, compartilhando com seus pacientes os potenciais danos, frequentemente omitidos, atribuídos ao rastreamento de cânceres, de modo a operacionalizar na prática a prevenção quaternária.

Position paper: breast cancer screening, diagnosis, and treatment in Denmark

BACKGROUND

During the last decades the diagnosis, treatment, and prognosis of breast cancer have changed and improved in Denmark. The first mammography screening programme started in 1991. However, for many years only about 20% of Danish women aged 50-69 were offered screening. The national roll-out of screening took place in 2008-2010.

MATERIAL AND METHODS

Based on published Danish data, this overview describes the status of diagnosis and treatment, and the screening programme. For further evaluating the potential overdiagnosis and overtreatment, additional Danish Breast Cancer Cooperative Group (DBCG) data are included.

RESULTS AND CONCLUSION

Using incidence-based mortality method, reduction in breast cancer mortality was estimated to be 25% in the target group of women after 10 years of screening in Copenhagen; an outcome comparable to that of randomised controlled trials. A recent Danish study has indicated overdiagnosis to be around 4%. Others have estimated overdiagnosis to be 33%. National DBCG data showed that the rude breast cancer incidence increased during the period 1990-2011 from 126 to 206 per 100 000. The incidence was almost constant for women younger than 50 years. In regions not offering screening, the incidence increased with 3% per year for women aged 50-69 years with similar trends for small and large tumours. After introduction of screening the increase in the age group 50-69 years was confined to small tumours ≤ 20 mm, and most pronounced for node negative patients. From the 1990s, the use of breast conserving surgery has increased from around 25% to 69% in 2010. Screening has not increased the number of mastectomies. Breast cancer treatment in Denmark is evidence based and in agreement with international recommendations. After the introduction of mammography screening the absolute number of patients with a more advanced stage at diagnosis and the absolute number of patients undergoing mastectomy have decreased.

Comparative analysis of breast cancer mortality following mammography screening in Denmark and Norway

BACKGROUND

Denmark and Norway are the best countries to study effects of mammography screening, because they are the only countries with stepwise introduction of nationwide mammography screening, enabling comparative effectiveness studies of high quality. Although Denmark and Norway are countries with similar populations and health care systems, reported reductions in breast cancer mortality (incidence-based) caused by screening differed vastly; 25% in Denmark versus 10% in Norway. This study explores reasons for this difference.

PATIENTS AND METHODS

We compared two published studies from the Danish and Norwegian screening programs (Olsen et al., 2005; Kalager et al., 2010) investigating biennial mammography screening for women age 50-69 years. Four comparison groups of women were constructed ('current' and 'historical screening groups'; 'current' and 'historical nonscreening groups') based on county of residence. We calculated incidence-based breast cancer mortality in the current versus the historical period for screening and nonscreening groups, using mortality rate ratios (MRR) in the two countries, accounting for concomitant changes in breast cancer mortality.

RESULTS

In the screening groups, similar reductions in breast cancer mortality were found when periods preceding and following start of screening were compared, in Denmark [25%; MRR 0.75; 95% confidence interval (CI) 0.64% to 0.88%] and in Norway (28%; MRR 0.72; 95% CI 0.63% to 0.81%). However, mortality increased in Denmark in the current nonscreening group compared with the historical nonscreening group; for women >59 years, breast cancer mortality increased by 14% (MRR 1.14, 95% CI 1.07-1.22), whereas in Norway a 19% reduction was seen (MRR 0.81, 95% CI 0.72-0.92). This increase accounts for the different relative effect of screening in Denmark and Norway; 25% breast cancer mortality reduction in Denmark, 10% in Norway.

CONCLUSIONS

The seemingly larger effect of screening in Denmark may not be solely attributable to screening itself, but to increased breast cancer mortality in women older than 59 years not invited to screening.

[Leaflets and websites on colorectal cancer screening and their quality assessment from experts' views]

In Germany, individuals who have statutory health insurance have free access to colorectal cancer (CRC) screening tests, and can choose between a fecal occult blood test and a screening colonoscopy. Evidence-based health information may support informed choices regarding whether or not to undergo CRC screening. The aim of this study was to assess whether the available German information materials on CRC screening meet evidence-based health information standards. A systematic search was made for print media and websites on CRC screening addressed to German people with average CRC risk (search period for print media August 2010, for websites January-March 2012). The identified information was assessed with a newly developed comprehensive list of criteria. In all, 41 print media, including 28 flyers and 13 brochures, and 36 websites were identified and assessed. These materials reported more often the benefits than the risks of CRC screening, and quantified presentations of benefits and risks were less frequently given. Most of the materials called for participation and did not indicate the option to decide whether or not to attend CRC screening. This bias in favor of screening was increased by fear-provoking or downplayed wording. Most materials included false and misleading information. The requirements for evidence-based patient information were currently not met by most of the leaflets and websites in Germany. Feedback was given to the producers of the leaflets including a discussion of the findings. The results may be used to revise existing leaflets or to develop new health information on CRC screening.

Development of a comprehensive list of criteria for evaluating consumer education materials on colorectal cancer screening

Background

Appropriate patient information materials may support the consumer’s decision to attend or not to attend colorectal cancer (CRC) screening tests (fecal occult blood test and screening colonoscopy). The aim of this study was to develop a list of criteria to assess whether written health information materials on CRC screening provide balanced, unbiased, quantified, understandable, and evidence-based health information (EBHI) about CRC and CRC screening.

Methods

The list of criteria was developed based on recommendations and assessment tools for health information in the following steps: (1) Systematic literature search in 13 electronic databases (search period: 2000–2010) and completed by an Internet search (2) Extraction of identified criteria (3) Grouping of criteria into categories and domains (4) Compilation of a manual of adequate answers derived from systematic reviews and S3 guidelines (5) Review by external experts (6) Modification (7) Final discussion with external experts.

Results

Thirty-one publications on health information tools and recommendations were identified. The final list of criteria includes a total of 230 single criteria in three generic domains (formal issues, presentation and understandability, and neutrality and balance) and one CRC-specific domain. A multi-dimensional rating approach was used whenever appropriate (e.g., rating for the presence, correctness, presentation and level of evidence of information). Free text input was allowed to ensure the transparency of assessment. The answer manual proved to be essential to the rating process. Quantitative analyses can be made depending on the level and dimensions of criteria.

Conclusions

This comprehensive list of criteria clearly has a wider range of evaluation than previous assessment tools. It is not intended as a final quality assessment tool, but as a first step toward thorough evaluation of specific information materials for their adherence to EBHI requirements. This criteria list may also be used to revise leaflets and to develop evidence-based health information on CRC screening. After adjustment for different procedure-specific criteria, the list of criteria can also be applied to other cancer screening procedures.

Influence of study features and methods on overdiagnosis estimates in breast and prostate cancer screening

Knowledge of the likelihood that a screening-detected case of cancer has been overdiagnosed is vitally important to make treatment decisions and develop screening policy. An overdiagnosed case is an excess case detected by screening. Estimates of the frequency of overdiagnosis in breast and prostate cancer screening vary greatly across studies. This article identifies features of overdiagnosis studies that influence results and shows their effect by using published research. First, different ways to define and measure overdiagnosis are considered. Second, contextual features and how they affect overdiagnosis estimates are examined. Third, the effect of estimation approach is discussed. Many studies use excess incidence under screening as a proxy for overdiagnosis. Others use statistical models to make inferences about lead time or natural history and then derive the corresponding fraction of cases that are overdiagnosed. This article concludes with questions that readers of overdiagnosis studies can use to evaluate the validity and relevance of published estimates and recommends that authors of studies quantifying overdiagnosis provide information about these features.

Screening for breast cancer with mammography

BACKGROUND

A variety of estimates of the benefits and harms of mammographic screening for breast cancer have been published and national policies vary.

OBJECTIVES

To assess the effect of screening for breast cancer with mammography on mortality and morbidity.

SEARCH METHODS

We searched PubMed (22 November 2012) and the World Health Organization's International Clinical Trials Registry Platform (22 November 2012).

SELECTION CRITERIA

Randomised trials comparing mammographic screening with no mammographic screening.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data. Study authors were contacted for additional information.

MAIN RESULTS

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).

AUTHORS' CONCLUSIONS

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.

Incidence and mortality trends for four major cancers in the elderly and middle-aged adults: an international comparison

BACKGROUND

Time trends comparisons by age are important to understand the specific needs of elderly cancer patients and to improve clinical procedures. The aim is to compare 1998-2005 cancer incidence and mortality trends in Italy and the US for both sexes and for two age groups, namely 50-69 year old and 70+ year old.

METHODS

Cancer incidence and mortality data came from 22 Cancer Registries (CRs) of the Italian association of cancer registries (AIRTUM), while the US incidence records were provided by 13 SEER CRs and the mortality statistics provided by the WHO Database. Trends were analysed by the Joinpoint Regression Program in order to obtain Annual Percent Changes and Joinpoints.

RESULTS

Colorectal cancer incidence trends were favourable in the US for both sexes and in both age groups, whilst the rates increased in Italian elderly individuals and mortality rates fell markedly only in the US. For lung cancer, incidence and mortality decreased in men but increased in women in the two geographical areas. Breast cancer incidence and mortality declined both in Italy and the US for younger women, but the trends were less favourable in the Italian elderly individuals. The increase of prostate incidence slowed down and mortality diminished for every age group in the US, whilst in Italy only in the younger group.

CONCLUSIONS

For major cancers, the Italian elderly experienced less favourable trends than the middle-aged patients whereas, in the US, the trends were similar for both age groups and favourable also for the elderly.

Overdiagnosis in screening mammography in Denmark: population based cohort study

OBJECTIVE

To use data from two longstanding, population based screening programmes to study overdiagnosis in screening mammography.

DESIGN

Population based cohort study.

SETTING

Copenhagen municipality (from 1991) and Funen County (from 1993), Denmark.

PARTICIPANTS

57,763 women targeted by organised screening, aged 56-69 when the screening programmes started, and followed up to 2009.

MAIN OUTCOME MEASURES

Overdiagnosis of breast cancer in women targeted by screening, assessed by relative risks compared with historical control groups from screening regions, national control groups from non-screening regions, and historical national control groups.

RESULTS

In total, 3279 invasive breast carcinomas and ductal carcinomas in situ occurred. The start of screening led to prevalence peaks in breast cancer incidence: relative risk 2.06 (95% confidence interval 1.64 to 2.59) for Copenhagen and 1.84 (1.46 to 2.32) for Funen. During subsequent screening rounds, relative risks were slightly above unity: 1.04 (0.85 to 1.27) for Copenhagen and 1.14 (0.98 to 1.32) for Funen. A compensatory dip was seen after the end of invitation to screening: relative risk 0.80 (0.65 to 0.98) for Copenhagen and 0.67 (0.55 to 0.81) for Funen during the first four years. The relative risk of breast cancer accumulated over the entire follow-up period was 1.06 (0.90 to 1.25) for Copenhagen and 1.01 (0.93 to 1.10) for Funen. Relative risks for participants corrected for selection bias were estimated to be 1.08 for Copenhagen and 1.02 for Funen; for participants followed for at least eight years after the end of screening, they were 1.05 and 1.01. A pooled estimate gave 1.040 (0.99 to 1.09) for all targeted women and 1.023 (0.97 to 1.08) for targeted women followed for at least eight years after the end of screening.

CONCLUSIONS

On the basis of combined data from the two screening programmes, this study indicated that overdiagnosis most likely amounted to 2.3% (95% confidence interval -3% to 8%) in targeted women. Among participants, it was most likely 1-5%. At least eight years after the end of screening were needed to compensate for the excess incidence during screening.