Overdiagnosis in mammographic screening for breast cancer in Europe: a literature review

A blueprint for cancer screening and early detection: Advancing screening's contribution to cancer control

From the mid-20th century, accumulating evidence has supported the introduction of screening for cancers of the cervix, breast, colon and rectum, prostate (via shared decisions), and lung. The opportunity to detect and treat precursor lesions and invasive disease at a more favorable stage has contributed substantially to reduced incidence, morbidity, and mortality. However, as new discoveries portend advancements in technology and risk-based screening, we fail to fulfill the greatest potential of the existing technology, in terms of both full access among the target population and the delivery of state-of-the art care at each crucial step in the cascade of events that characterize successful cancer screening. There also is insufficient commitment to invest in the development of new technologies, incentivize the development of new ideas, and rapidly evaluate promising new technology. In this report, the authors summarize the status of cancer screening and propose a blueprint for the nation to further advance the contribution of screening to cancer control.

Overview of Breast Cancer Screening and Diagnosis

Screening mammography saves lives. The mainstay of screening has been mammography. Multiple alternative options, however, for supplemental imaging are now available. Some are just improved anatomic delineation whereas others include physiology added to anatomy. A third group (molecular imaging) is purely physiologic. This article describes and compares the available options and for which patient populations they should be used.

Overdiagnosis in the population-based organized breast cancer screening program estimated by a non-homogeneous multi-state model: a cohort study using individual data with long-term follow-up

Background

Overdiagnosis, defined as the detection of a cancer that would not become clinically apparent in a woman’s lifetime without screening, has become a growing concern. Similar underlying risk of breast cancer in the screened and control groups is a prerequisite for unbiased estimates of overdiagnosis, but a contemporary control group is usually not available in organized screening programs.

Methods

We estimated the frequency of overdiagnosis of breast cancer due to screening in women 50–69 years old by using individual screening data from the population-based organized screening program in Stockholm County 1989–2014. A hidden Markov model with four latent states and three observed states was constructed to estimate the natural progression of breast cancer and the test sensitivity. Piecewise transition rates were used to consider the time-varying transition rates. The expected number of detected non-progressive breast cancer cases was calculated.

Results

During the study period, 2,333,153 invitations were sent out; on average, the participation rate in the screening program was 72.7% and the average recall rate was 2.48%. In total, 14,648 invasive breast cancer cases were diagnosed; among the 8305 screen-detected cases, the expected number of non-progressive breast cancer cases was 35.9, which is equivalent to 0.43% (95% confidence interval (CI) 0.10%–2.2%) overdiagnosis. The corresponding estimates for the prevalent and subsequent rounds were 15.6 (0.87%, 95% CI 0.20%–4.3%) and 20.3 (0.31%, 95% CI 0.07%–1.6%), respectively. The likelihood ratio test showed that the non-homogeneous model fitted the data better than an age-homogeneous model (P <0.001).

Conclusions

Our findings suggest that overdiagnosis in the organized biennial mammographic screening for women 50–69 in Stockholm County is a minor phenomenon. The frequency of overdiagnosis in the prevalent screening round was higher than that in subsequent rounds. The non-homogeneous model performed better than the simpler, traditional homogeneous model.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-1082-z) contains supplementary material, which is available to authorized users.

Risk Stratification for Screening Mammography: Benefits and Harms

OBJECTIVE

The purpose of this article is to compare commonly used breast cancer risk assessment models, describe the machine learning approach and big data in risk prediction, and summarize the potential benefits and harms of restrictive risk-based screening.

CONCLUSION

The commonly used risk assessment models for breast cancer can be complex and cumbersome to use. Each model incorporates different sets of risk factors, which are weighted differently and can produce different results for the same patient. No model is appropriate for all subgroups of the general population and only one model incorporates mammographic breast density. Future development of risk prediction tools that are generalizable and simpler to use are needed in guiding clinical decisions.

Role of Clinical and Imaging Risk Factors in Predicting Breast Cancer Diagnosis Among BI-RADS 4 Cases

PURPOSE

To analyze women with suspicious findings (assessed as Breast Imaging Reporting and Data System [BI-RADS] 4), examining the value of clinical and imaging predictors in predicting cancer diagnosis.

PATIENTS AND METHODS

A set of 2138 examinations (1978 women) given a BI-RADS 4 with matching pathology results were analyzed. Predictors such as patient demographics, clinical risk factors, and imaging-derived features such as BI-RADS assessment and qualitative breast density were considered. Independent predictors of breast cancer were determined by univariate analysis and multivariate logistic regression.

RESULTS

In univariate analysis, age, race, body mass index, age at first live birth, BI-RADS assessment, qualitative breast density, and risk triggers were found to be independent predictors. In multivariate analysis, age, BI-RADS score, breast density, race, presence of a lump, and number of risk triggers were the most predictive. An integrative logistic regression model achieved a performance of 0.84 cross-validated area under the curve. No variable was a constant independent predictor when stratifying the population on the basis of the BI-RADS score.

CONCLUSION

While BI-RADS assessment remains the strongest predictor of breast cancer, the inclusion of clinical risk factors such as age, breast density, presence of a lump, and number of risk triggers derived from guidelines improves the specificity of identifying individuals with imaging descriptors associated with BI-RADS 4A and 4B that are more likely to be diagnosed with breast cancer.

[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.

Overdiagnosis in primary care: framing the problem and finding solutions

Overdiagnosis, is defined as the diagnosis of a condition that, if unrecognized, would not cause symptoms or harm a patient during his or her lifetime, and it is increasingly acknowledged as a consequence of screening for cancer and other conditions. Because preventive care is a crucial component of primary care, which is delivered to the broad population, overdiagnosis in primary care is an important problem from a public health perspective and has far reaching implications. The scope of overdiagnosis as a result of services delivered in primary care is unclear, though overdiagnosis of indolent breast, prostate, thyroid, and lung cancers is well described and overdiagnosis of chronic kidney disease, depression, and attention-deficit/hyperactivity disorder is also recognized. However, overdiagnosis is a known consequence of all screening and can be assumed to occur in many more clinical contexts. Overdiagnosis can harm patients by leading to overtreatment (with associated potential toxicities), diagnosis related anxiety or depression, and labeling, or through financial burden. Many entrenched factors facilitate overdiagnosis, including the growing use of advanced diagnostic technology, financial incentives, a medical culture that encourages greater use of tests and treatments, limitations in the evidence that obscure the understanding of diagnostic utility, use of non-beneficial screening tests, and the broadening of disease definitions. Efforts to reduce overdiagnosis are hindered by physicians' and patients' lack of awareness of the problem and by confusion about terminology, with overdiagnosis often conflated with related concepts. Clarity of terminology would facilitate physicians' understanding of the problem and the growth in evidence regarding its prevalence and downstream consequences in primary care. It is hoped that international coordination regarding diagnostic standards for disease definitions will also help minimize overdiagnosis in the future.

The added value of mammography in different age-groups of women with and without BRCA mutation screened with breast MRI

Background

Breast magnetic resonance imaging (MRI) is the most sensitive imaging method for breast cancer detection and is therefore offered as a screening technique to women at increased risk of developing breast cancer. However, mammography is currently added from the age of 30 without proven benefits. The purpose of this study is to investigate the added cancer detection of mammography when breast MRI is available, focusing on the value in women with and without BRCA mutation, and in the age groups above and below 50 years.

Methods

This retrospective single-center study evaluated 6553 screening rounds in 2026 women at increased risk of breast cancer (1 January 2003 to 1 January 2014). Risk category (BRCA mutation versus others at increased risk of breast cancer), age at examination, recall, biopsy, and histopathological diagnosis were recorded. Cancer yield, false positive recall rate (FPR), and false positive biopsy rate (FPB) were calculated using generalized estimating equations for separate age categories (< 40, 40–50, 50–60, ≥ 60 years). Numbers of screens needed to detect an additional breast cancer with mammography (NSN) were calculated for the subgroups.

Results

Of a total of 125 screen-detected breast cancers, 112 were detected by MRI and 66 by mammography: 13 cancers were solely detected by mammography, including 8 cases of ductal carcinoma in situ. In BRCA mutation carriers, 3 of 61 cancers were detected only on mammography, while in other women 10 of 64 cases were detected with mammography alone. While 77% of mammography-detected-only cancers were detected in women ≥ 50 years of age, mammography also added more to the FPR in these women. Below 50 years the number of mammographic examinations needed to find an MRI-occult cancer was 1427.

Conclusions

Mammography is of limited added value in terms of cancer detection when breast MRI is available for women of all ages who are at increased risk. While the benefit appears slightly larger in women over 50 years of age without BRCA mutation, there is also a substantial increase in false positive findings in these women.

Breast and cervical cancer incidence and mortality trends in Russia 1980-2013

BACKGROUND

Breast and cervical cancer are among the leading causes of preventable cancer deaths in women in Russia. The aim of this study is to analyze changes in breast and cervical cancer incidence and mortality trends using data from the Russian State Cancer Registry.

METHODS

The age-standardized rates of cervical cancer incidence (1993-2013) and mortality (1980-2013) were analyzed using piecewise linear regression. Age-period-cohort models were used to estimate the temporal effects and provide future predictions.

RESULTS

Breast and cervical cancer incidence rates uniformly increased over two decades from 33.0 to 47.0 per 100,000 and from 10.6 to 14.2 per 100,000, respectively. Breast cancer mortality rates however declined from 17.6 to 15.7 in 2013, while cervical cancer mortality increased steadily from 5.6 to 6.7. Breakpoints in the risk occurred in cohorts born 1937-1953, indicating a recent generational decrease in breast cancer mortality, but a concomitant increase in cervical cancer. Cervical cancer has already surpassed breast cancer in terms of years of life lost (YLL) (23.4 per death vs 18.5 in 2009-2013), while future projections suggest that the annual YLL could reach 1.2 million for cervical cancer and (decline to) 1.8 million for breast cancer by the year 2030.

CONCLUSION

The temporal patterns of breast cancer incidence and mortality in Russia are in line with other countries in Europe, although cervical cancer rates and the risk of occurrence in recent generations is rapidly increasing; these trends underscore the need to place immediate priority in national cervical vaccination and screening programs.

Autoantibodies as Potential Biomarkers in Breast Cancer

Breast cancer is a major cause of mortality in women; however, technologies for early stage screening and diagnosis (e.g., mammography and other imaging technologies) are not optimal for the accurate detection of cancer. This creates demand for a more effective diagnostic means to replace or be complementary to existing technologies for early discovery of breast cancer. Cancer neoantigens could reflect tumorigenesis, but they are hardly detectable at the early stage. Autoantibodies, however, are biologically amplified and hence may be measurable early on, making them promising biomarkers to discriminate breast cancer from healthy tissue accurately. In this review, we summarized the recent findings of breast cancer specific antigens and autoantibodies, which may be useful in early detection, disease stratification, and monitoring of treatment responses of breast cancer.

Defining, Estimating, and Communicating Overdiagnosis in Cancer Screening

The toll of inadequate health care is well-substantiated, but recognition is mounting that "too much" is also possible. Overdiagnosis represents one harm of too much medicine, but the concept can be confusing: It is often conflated with related harms (such as overtreatment, misclassification, false-positive results, and overdetection) and is difficult to measure because it cannot be directly observed. Because the U.S. Preventive Services Task Force (USPSTF) issues screening recommendations aimed largely at healthy persons, it has a particular interest in understanding harms related to screening, especially but not limited to overdiagnosis. In support of the USPSTF, the authors summarize the knowledge and provide guidance on defining, estimating, and communicating overdiagnosis in cancer screening. To improve consistency, thinking, and reporting about overdiagnosis, they suggest a specific definition. The authors articulate how variation in estimates of overdiagnosis can arise, identify approaches to estimating overdiagnosis, and describe best practices for communicating the potential for harm due to overdiagnosis.

Complexities of perceived and actual performance in pathology interpretation: A comparison of cutaneous melanocytic skin and breast interpretations

BACKGROUND

Little is known about how pathologists process differences between actual and perceived interpretations.

OBJECTIVE

To compare perceived and actual diagnostic agreement before and after educational interventions.

METHODS

Pathologists interpreted test sets of skin and/or breast specimens that included benign, atypical, in situ and invasive lesions. Interventions involved self-directed learning, one skin and one breast, that showed pathologists how their interpretations compared to a reference diagnoses. Prior to the educational intervention, participants estimated how their interpretations would compare to the reference diagnoses. After the intervention, participants estimated their overall agreement with the reference diagnoses. Perceived and actual agreements were compared.

RESULTS

For pathologists interpreting skin, mean actual agreement was 52.4% and overall pre- and postinterventional mean perceived agreement was 72.9% vs 54.2%, an overestimated mean difference of 20.5% (95% confidence interval [CI] 17.2% to 24.0%) and 1.8% (95% CI -0.5% to 4.1%), respectively. For pathologists interpreting breast, mean actual agreement was 75.9% and overall pre- and postinterventional mean perceived agreement was 81.4% vs 76.9%, an overestimation of 5.5% (95% CI 3.0% to 8.0%) and 1.0% (95% CI 0.0% to 2.0%), respectively.

CONCLUSIONS

Pathologists interpreting breast tissue had improved comprehension of their performance after the intervention compared to pathologists interpreting skin lesions.

Screening for breast cancer in 2018-what should we be doing today?

Although screening mammography has delivered many benefits since its introduction in Canada in 1988, questions about perceived harms warrant an up-to-date review. To help oncologists and physicians provide optimal patient recommendations, the literature was reviewed to find the latest guidelines for screening mammography, including benefits and perceived harms of overdiagnosis, false positives, false negatives, and technologic advances. For women 40-74 years of age who actually participate in screening every 1-2 years, breast cancer mortality is reduced by 40%. With appropriate corrections, overdiagnosis accounts for 10% or fewer breast cancers. False positives occur in about 10% of screened women, 80% of which are resolved with additional imaging, and 10%, with breast biopsy. An important limitation of screening is the false negatives (15%-20%). The technologic advances of digital breast tomosynthesis, breast ultrasonography, and magnetic resonance imaging counter the false negatives of screening mammography, particularly in women with dense breast tissue.

Addition of ultrasound to mammography in the case of dense breast tissue: systematic review and meta-analysis

BACKGROUND

Mammography is less effective in detecting cancer in dense than in fatty breasts.

METHODS

We undertook a systematic search in PubMed to identify studies on women with dense breasts who underwent screening with mammography supplemented with ultrasound. A meta-analysis was undertaken on the proportion of cancers detected only by ultrasound, out of all screen-detected cancers, and the proportion of women with negative mammography who were referred for assessment following ultrasound screening.

RESULTS

Twenty-nine studies satisfied our inclusion criteria. The proportion of total cancers detected only by ultrasound was 0.29 (95% CI: 0.27-0.31), consistent with an approximately 40% increase in the detection of cancers compared to mammography. In the studied populations, this translated into an additional 3.8 (95% CI: 3.4-4.2) screen-detected cases per 1000 mammography-negative women. About 13% (32/248) of cancers were in situ from 17 studies with information on this subgroup. Ultrasound approximately doubled the referral for assessment in three studies with these data.

CONCLUSIONS

Studies have consistently shown an increased detection of breast cancer by supplementary ultrasound screening. An inclusion of supplementary ultrasound into routine screening will need to consider the availability of ultrasound and diagnostic assessment capacities.

Treatment Intensity Differences After Early-Stage Breast Cancer (ESBC) Diagnosis Depending on Participation in a Screening Program

BACKGROUND

While population mammographic screening identifies early-stage breast cancers (ESBCs; ductal carcinoma in situ [DCIS] and invasive disease stages 1-3A), commentaries suggest that harms from overdiagnosis and overtreatment may outweigh the benefits. Apparent benefits to patients with screen-detected cancers may be due to selection bias from exclusion of interval cancers (ICs). Treatment intensity is rarely discussed, with an assumption that all ESBCs are treated similarly. We hypothesized that women diagnosed while in a screening program would receive less-intense treatment than those never or not recently screened (NRS).

METHODS

This was a retrospective analysis of all women aged 50-69 years managed for ESBC (invasive or DCIS) during the period 2007-2013 within a single service, comparing treatment according to screening status. Data on demographics, detection, pathology, and treatment were derived from hospital, cancer registry, and screening service records.

RESULTS

Overall, 622 patients were active screeners (AS) at diagnosis (569 screen-detected and 53 ICs) and 169 patients were NRS. AS cancers were smaller (17 mm vs. 26 mm, p < 0.0001), less likely to involve nodes (26% vs. 48%, p < 0.0001), and lower grade. For invasive cancer, NRS patients were more likely to be recommended for mastectomies [35% vs. 16%; risk ratio(RR) 2.2, p < 0.0001], axillary dissection (43% vs. 19%; RR 2.3, p < 0.0001), adjuvant chemotherapy (65% vs. 37%; RR 1.7, p < 0.0001), and postmastectomy radiotherapy (58% vs. 39%; RR 1.5, p = 0.04).

CONCLUSION

Participants in population screening diagnosed with ESBC receive substantially less-intense treatment than non-participants. Differences persist when potential overdiagnosis is taken into account; these differences should be factored into debates around mammographic screening.

Overdiagnosis in imaging

Overdiagnosis, more than an error regarding the diagnosis, is an error regarding the prognosis. We cannot know what consequences some lesions that we detect by imaging would have on our patients' lives if they were left untreated. As long as it is not possible for imaging techniques to differentiate between lesions that will have an indolent course from those that will have an aggressive course, there will be overdiagnosis. Advanced imaging techniques, radiomics, and radiogenomics, together with artificial intelligence, promise advances in this sense. In the meantime, it is important that radiologists be careful to ensure that only strictly necessary imaging tests are done. Moreover, we need to participate, together with patients, in making multidisciplinary decisions about diagnosis and clinical management. Finally, of course, we need to continue to contribute to the technological and scientific advance of our profession, so that we can continue to improve the diagnosis and early detection of abnormalities, especially those that require treatment.

Aggressive primary treatments with favourable 5-year survival for screen-interval breast cancers

Background

To assess the impact of the participation in screening programme according to the mode of detection on the early diagnosis, treatment, and specific survival outcomes in women with breast cancer.

Methods

Women diagnosed with invasive breast cancer in Poitou-Charentes region (France) between 2008 and 2009 were classified into three groups, using data linkage of cancer registry, vital statistics and French organized screening programme: the screening programme (SP), interval cancer (IC), and non-screening programme detected cancer (NSP) groups. Specific survival rates were analysed using the Kaplan–Meier method and Cox proportional hazard models.

Results

Among 1613 patients, 65.7% (n = 1059) participated in a screening programme. The interval cancer rate was 17.1% (n = 181). Tumours in the IC group were diagnosed at a more advanced stage, i.e. with further regional lymph node metastasis or local spread, than those in the SP group (p < 0.001), but with significantly fewer metastases at diagnosis than in the NSP group (p < 0.001). ICs underwent more aggressive primary treatments than the two other groups, with 28% of radical mastectomy and 67% undergoing chemotherapy. The five-year survival rate for IC group were 92.0% (95% CI, 89.9–94.0%).

Conclusions

Interval cancers had more aggressive features than screen-detected cancers but were diagnosed at a less advanced stage compared to non-screen detected cancers. Despite having cancers missed by the screening programme, women who participate in the screening process seem to benefit from early treatment. These results must be confirmed with long-term follow-up.

Prevalence of incidental breast cancer and precursor lesions in autopsy studies: a systematic review and meta-analysis

Background

Autopsy studies demonstrate the prevalence pool of incidental breast cancer in the population, but estimates are uncertain due to small numbers in any primary study. We aimed to conduct a systematic review of autopsy studies to estimate the prevalence of incidental breast cancer and precursors.

Methods

Relevant articles were identified through searching PubMed and Embase from inception up to April 2016, and backward and forward citations. We included autopsy studies of women with no history of breast pathology, which included systematic histological examination of at least one breast, and which allowed calculation of the prevalence of incidental breast cancer or precursor lesions. Data were pooled using logistic regression models with random intercepts (non-linear mixed models).

Results

We included 13 studies from 1948 to 2010, contributing 2363 autopsies with 99 cases of incidental cancer or precursor lesions. More thorough histological examination (≥20 histological sections) was a strong predictor of incidental in-situ cancer and atypical hyperplasia (OR = 126·8 and 21·3 respectively, p < 0·001), but not invasive cancer (OR = 1·1, p = 0·75). The estimated mean prevalence of incidental cancer or precursor lesion was 19·5% (0·85% invasive cancer + 8·9% in-situ cancer + 9·8% atypical hyperplasia).

Conclusion

Our systematic review in ten countries over six decades found that incidental detection of cancer in situ and breast cancer precursors is common in women not known to have breast disease during life. The large prevalence pool of undetected cancer in-situ and atypical hyperplasia in these autopsy studies suggests screening programs should be cautious about introducing more sensitive tests that may increase detection of these lesions.

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.

Estimation of overdiagnosis in breast cancer screening using a non-homogeneous multi-state model: A simulation study

Objectives

Overdiagnosis is regarded as a harm of screening. We aimed to develop a non-homogeneous multi-state model to consider the age-specific transition rates for estimation of overdiagnosis, to validate the model by a simulation study where the true frequency of overdiagnosis can be calculated, and to compare our estimate with the cumulative incidence method.

Methods

We constructed a four-state model to describe the natural history of breast cancer. The latent disease progression and the observed states for each individual were simulated in a trial with biennial screening of women aged 51–69 and a control group of the same size without screening. We performed 100 repetitions of the simulation with one million women to evaluate the performance of estimates. A sensitivity analysis with reduced number of controls was performed to imitate the data from the service screening programme.

Results

Based on the 100 repetitions, the mean value of the true frequency of overdiagnosis was 12.5% and the average estimates by the cumulative incidence method and the multi-state model were 12.9% (interquartile range: 2.46%) and 13.4% (interquartile range: 2.16%), respectively. The multi-state model had a greater bias of overdiagnosis than the cumulative incidence method, but the variation in the estimates was smaller. When the number of unscreened group was reduced, the variation of multi-state model estimates increased.

Conclusions

The multi-state model produces a proper estimate of overdiagnosis and the results are comparable with the cumulative incidence method. The multi-state model can be used in the estimation of overdiagnosis, and might be useful for the ongoing service screening programmes.

Breast cancer in the 21st century: from early detection to new therapies

The analysis of the causes that have given rise to a change in tendency in the incidence and mortality rates of breast cancer in the last few decades generates important revelations regarding the role of breast screening, the regular application of adjuvant therapies and the change of risk factors. The benefits of early detection have been accompanied by certain adverse effects, even in terms of an excessive number of prophylactic mastectomies. Recently, several updates have been published on the recommendations in breast cancer screening at an international level. On the other hand, the advances in genomics have made it possible to establish a new molecular classification of breast cancer. Our aim is to present an updated overview of the epidemiological situation of breast cancer, as well as some relevant issues from the point of view of diagnosis, such as molecular classification and different strategies for both population-based and opportunistic screening.

The Breast Cancer Screening "Arcade" and the "Whack-A-Mole" Efforts to Reduce Access to Screening

The effort to reduce access to breast cancer screening has been going on for decades. As each piece of misinformation has been published, scientific responses have exposed the fallacies, but then new "alternative facts" are generated. The effort has been compared to the arcade game "Whack-a-Mole" in which one false argument is addressed only to have a new one "pop up" to replace it. This has ranged from the false claim that early detection would have no effect on breast cancer, to the fallacious idea that early detection was leading to early deaths among young women, to the more recent false suggestion that tens of thousands of breast cancers found by mammography would disappear if left undetected. The following is a short review of a number of nonscientifically derived "Moles" that have been "Whacked" by science.

Exploring disparities in incidence and mortality rates of breast and gynecologic cancers according to the Human Development Index in the Pan-American region

OBJECTIVE

To evaluate whether a country's Human Development Index (HDI) can help explain the differences in the country's breast cancer and gynecological cancer incidence and mortality rates in the Pan-American region.

STUDY DESIGN

Ecological analysis.

METHODS

Pan-American region countries with publicly available data both in GLOBOCAN 2012 and the United Nations Development Report 2012 were included (n = 28). Incidence and mortality rates age-standardized per 100,000 were natural log-transformed for breast cancer, ovarian cancer, corpus uteri cancer, and cervical cancer. The mortality-to-incidence ratio (MIR) was calculated for each site. Pearson's correlation test and a simple linear regression were performed.

RESULTS

The HDI showed a positive correlation with breast cancer and ovarian cancer incidence and mortality rates, respectively, and a negative correlation with cervical cancer incidence and mortality rates. The HDI and corpus uteri cancer showed no association. MIR and the HDI showed a negative correlation for all tumor types except ovarian cancer. An increment in 1 HDI unit leads to changes in cancer rates: in breast cancer incidence β = 4.03 (95% confidence interval [CI] 2.61; 5.45) P < 0.001, breast cancer mortality β = 1.76 (95% CI 0.32; 3.21) P = 0.019, and breast cancer-MIR β = -0.705 (95% CI 0.704; 0.706) P < 0.001; in cervical cancer incidence β = -3.28 (95% CI -4.78; -1.78) P < 0.001, cervical cancer mortality β = -4.63 (95% CI -6.10; -3.17) P < 0.001, and cervical cancer-MIR β = -1.35 (95% CI -1.83; -0.87) P < 0.001; in ovarian cancer incidence β = 3.26 (95% CI 1.78; 4.75) P < 0.001, ovarian cancer mortality β = 1.82 (95% CI 0.44; 3.20) P = 0.012, and ovarian cancer-MIR β = 5.10 (95% CI 3.22; 6.97) P < 0.001; in corpus uteri cancer incidence β = 2.37 (95% CI -0.33; 5.06) P = 0.83, corpus uteri cancer mortality β = 0.68 (95% CI -2.68; 2.82) P = 0.96, and corpus uteri cancer-MIR β = -2.30 (95% CI -3.19; -1.40) P < 0.001.

CONCLUSIONS

A country's HDI should be considered to understand disparities in breast cancer and gynecological cancer in the Pan-American region.

The Canadian National Breast Screening Studies are compromised and their results are unreliable. They should not factor into decisions about breast cancer screening

The Canadian National Breast Screening Studies were compromised by an unblinded allocation process and poor quality mammography. Contrary to the requirement that allocation in a randomized controlled trial (RCT) be blinded to avoid any possible intentional or unintentional subversion of a random allocation, all women in the CNBSS trials underwent a clinical breast examination prior to assignment to the study arm or the usual care arm. Women with abnormal clinical breast examinations were identified, and this information was available to the coordinators who then assigned the women on open lists. It was, therefore, possible to assign women to whichever arm the coordinator chose. Although subversion was likely unintended, a significant number of women with four or more positive axillary lymph nodes were assigned to the screening arm of CNBSS1. This explains why there were more breast cancer deaths among the screened women in the first ten years of the trial and why the 5 year survival of the control women was better than 90% when the background survival in Canada at the time was only 75%. The trials were further compromised by the poor quality of the mammography which was confirmed by a review conducted by the trials' organizers. These fundamental problems compromise the CNBSS and make their results, which are major outliers in the RCT's of breast cancer screening, unreliable. Consequently, they should not be used to establish guidelines for breast cancer screening.