Screening mammography: update and review of publications since our report in the New England Journal of Medicine on the magnitude of the problem in the United States

Mammography screening and mortality by risk status in the California teachers study

Background

The debate continues among medical professionals regarding the frequency, starting age, and stopping age for mammography screening. Some experts suggest tailoring recommendations based on individuals’ personal breast cancer risk. Previous studies have not compared the impact of annual versus biennial mammography stratified by age group and risk category. The purpose of this study was to examine the relationship between mammography frequency and mortality by age group and risk category in the California Teachers Study.

Methods

Using data from study questionnaires from 93,438 women between the ages of 40 and 85 and linkages to the California Cancer Registry and other indices, overall and breast cancer-specific mortality by mammography frequency were estimated using multivariable Cox proportional hazards models, stratified by age group and risk category at baseline as determined by the Gail breast cancer risk model.

Results

During the follow-up period of 20 years, overall mortality risk was lower in women who had annual or biennial mammography compared to less frequent or no mammography in all age groups. Annual mammography was associated with lower overall mortality risk compared to biennial mammography among women age 50–85. This difference was especially apparent in women age 60–74, regardless of estimated Gail risk category at baseline. Breast cancer-specific mortality was lower among women who had annual mammography compared to biennial or less frequent mammography among women age 60–74, regardless of their baseline risk.

Conclusions

Our findings suggest that at least biennial mammography is beneficial to most women age 40–85 and that annual mammography is more beneficial than biennial mammography to most women age 50–85 in terms of overall mortality.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-09071-1.

Life-Saving Cancer Care

What, precisely, are we seeking to achieve in offering 'life-saving' treatment to patients with cancer? Research funding agencies and pharmaceutical industry media releases, and government cancer screening programs all promise that their cancer programs save lives. But everybody dies. The nature of life and death from cancer is explored philosophically in this essay, with particular reference to the quality of life, and its meaning, during the period of prolongation of survival by 'life-saving' cancer care.

Breast Cancer Screening in Women With Schizophrenia: A Systematic Review and Meta-Analysis

OBJECTIVE

Women with schizophrenia appear to receive breast cancer diagnoses at later stages of the disease compared with the general population. To study this disparity, this report reviewed and quantified the differences in rates of mammography screening for women with schizophrenia and other psychotic disorders compared with the general population.

METHODS

A systematic literature search was conducted in PubMed, Embase, Web of Science, and PsycINFO databases. Each database was searched from inception to September 14, 2018. The search strategy included search terms for breast cancer, mammography, schizophrenia, and psychosis. Two reviewers independently screened and evaluated eligible studies. The main outcome measure was the rate of mammography screening among women with schizophrenia and psychotic disorders versus a comparable population of women without these diagnoses. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were used for abstracting data, and the Newcastle-Ottawa Scale was used for assessing data quality. A meta-analysis with a random-effects model was performed.

RESULTS

From a total of 304 abstracts reviewed, 11 studies met the inclusion criteria, representing 25,447 women with diagnoses of schizophrenia or psychosis across four countries. The meta-analysis showed that women with schizophrenia were less likely than women without schizophrenia to receive mammography screening (pooled OR=0.50, 95% confidence interval=0.38-0.64, p<0.001). In subgroup analysis, this association was not significantly affected by quality of the study.

CONCLUSIONS

Women with schizophrenia and other psychotic disorders were about half as likely as the general population to receive mammography screening. Further research is needed to determine causes of this disparity.

Long-term relationships between screening rates, breast cancer characteristics, and overdiagnosis in US counties, 1975-2009

Effects of mammography screening in the general population are disputed. Screening rates differ greatly between US counties, providing a natural opportunity to investigate effects of screening. We compared mammography screening rates with the types and outcomes of breast cancers diagnosed in US counties. The county screening rate was defined as the proportion of women age ≥40 with ≥1 mammogram in the past 2 years (range, 34-91%). Two periods were analyzed: 1975-2009 (612,941 breast cancer cases, 195 counties) and 1996-2009 (645,057 cases, 211-547 counties). Multiple signs of overdiagnosis were observed: First, breast cancer incidence increased as screening became common. Second, incidence stopped increasing once screening rates stabilized. Third, the increases in incidence were limited to age groups receiving screening. Fourth, the increases were larger in counties where screening became more common. Fifth, the increases were limited to small and early-stage breast cancers (which are consistent with overdiagnosis). Sixth, compensatory reductions in large and advanced-stage breast cancers were much smaller than the increases. Difference-in-differences regression analysis suggested 31% (95% CI: 28-34%) of breast cancers diagnosed in 1996-2009 were overdiagnosed. Screening rates correlated with increased incidence for all hormone receptor statuses, HER2 statuses, and grades. Reductions in breast cancer mortality during 1975-2009 were similar in screened and unscreened age groups. Overall, we found repeated signs that breast cancer overdiagnosis is widespread in the US, but the biological nature of overdiagnosed tumors remains unclear. Mortality benefits of screening, though they may be present and substantial, could not be detected at the population level.

How Do Women View Risk-Based Mammography Screening? A Qualitative Study

BACKGROUND

Decades of persuasive messages have reinforced the importance of traditional screening mammography at regular intervals. A potential new paradigm, risk-based screening, adjusts mammography frequency based on a woman's estimated breast cancer risk in order to maximize mortality reduction while minimizing false positives and overdiagnosis. Women's views of risk-based screening are unknown.

OBJECTIVE

To explore women's views and personal acceptability of a potential risk-based mammography screening paradigm.

DESIGN

Four semi-structured focus group discussions about screening mammography and surveys before provision of information about risk-based screening. We analyzed coded focus group transcripts using a mixed deductive (content analysis) and inductive (grounded theory) approach.

PARTICIPANTS

Convenience sample of 29 women (40-74 years old) with no personal history of breast cancer recruited by print and online media in New Hampshire and Vermont.

RESULTS

Twenty-seven out of 29 women reported having undergone mammography screening. All participants were white and most were highly educated. Some women accepted the idea that early cancer detection with traditional screening was beneficial-although many also reported hearing inconsistent recommendations from clinicians and mixed messages from media reports about mammography. Some women were familiar with a risk-based screening paradigm (primarily related to cervical cancer, n = 8) and thought matching screening mammography frequency to personal risk made sense (n = 8). Personal acceptability of risk-based screening was mixed. Some believed risk-based screening could reduce the harms of false positives and overdiagnosis (n = 7). Others thought screening less often might result in missing a dangerous diagnosis (n = 14). Many (n = 18) expressed concerns about the feasibility of risk-based screening and questioned whether breast cancer risk estimates could be accurate. Some suspected that risk-based mammography was motivated by a desire to save money (n = 6).

CONCLUSION

Some women thought risk-based screening made sense. Willingness to abandon traditional screening for the new paradigm was mixed. Broad acceptability of risk-based screening will require clearer communication about its rationale and feasibility and consistent messages from the health care team.

Is an indistinct picture "exactly what we need"? Objectivity, accuracy, and harm in imaging for cancer

Assumptions about the epistemic ideal of objectivity, closely related to ontological assumptions about the nature of disease as pathophysiological abnormality, lead us into oversimplified ways of thinking about medical imaging. This is illustrated by current controversies in the early detection of cancer. Improvements in the technical quality of imaging failed to address the problem of overdiagnosis in breast cancer screening and exacerbate the problem in thyroid cancer diagnosis. Drawing on Douglas and on Daston and Galison, I distinguish 3 dimensions of objectivity (accuracy, reliability, and precision) and demonstrate ways they may be at odds, as illustrated in the early detection of cancer. Guidelines for evaluating the efficacy of diagnostic imaging are insufficiently sensitive to this complexity. Improving imaging quality may raise epistemic issues, place disease definitions in question, and lead to overall harm or to changes in the distribution of harms and benefits among population subgroups. With a nod to Wittgenstein, I argue that we cannot take for granted that "an indistinct picture" is not "exactly what we need."

Impact of screening mammography on breast cancer mortality

The degree to which observed reductions in breast cancer mortality is attributable to screening mammography has become increasingly controversial. We examined this issue with three fundamentally different approaches: (i) Chronology--the temporal relationship of the onset of breast cancer mortality decline and the national implementation of screening mammography; (ii) Magnitude--the degree to which breast cancer mortality declined relative to the amount (penetration) of screening mammography; (iii) Analogy--the pattern of mortality rate reductions of other cancers for which population screening is not conducted. Chronology and magnitude were assessed with data from Europe and North America, with three methods applied to magnitude. A comparison of eight countries in Europe and North America does not demonstrate a correlation between the penetration of national screening and either the chronology or magnitude of national breast cancer mortality reduction. In the United States, the magnitude of the mortality decline is greater in the unscreened, younger women than in the screened population and regional variation in the rate of breast cancer mortality reduction is not correlated with screening penetrance, either as self-reported or by the magnitude of screening-induced increase in early-stage disease. Analogy analysis of United States data identifies 14 other cancers with a similar distinct onset of mortality reduction for which screening is not performed. These five lines of evidence from three different approaches and additional observations discussed do not support the hypothesis that mammography screening is a primary reason for the breast cancer mortality reduction in Europe and North America.

Implications of Overdiagnosis: Impact on Screening Mammography Practices

This review article explores the issue of overdiagnosis in screening mammography. Overdiagnosis is the screen detection of a breast cancer, histologically confirmed, that might not otherwise become clinically apparent during the lifetime of the patient. While screening mammography is an imperfect tool, it remains the best tool we have to diagnose breast cancer early, before a patient is symptomatic and at a time when chances of survival and options for treatment are most favorable. In 2015, an estimated 231,840 new cases of breast cancer (excluding ductal carcinoma in situ) will be diagnosed in the United States, and some 40,290 women will die. Despite these data, screening mammography for women ages 40-69 has contributed to a substantial reduction in breast cancer mortality, and organized screening programs have led to a shift from late-stage diagnosis to early-stage detection. Current estimates of overdiagnosis in screening mammography vary widely, from 0% to upwards of 30% of diagnosed cancers. This range reflects the fact that measuring overdiagnosis is not a straightforward calculation, but usually one based on different sets of assumptions and often biased by methodological flaws. The recent development of tomosynthesis, which creates high-resolution, three-dimensional images, has increased breast cancer detection while reducing false recalls. Because the greatest harm of overdiagnosis is overtreatment, the key goal should not be less diagnosis but better treatment decision tools. (Population Health Management 2015;18:S3-S11).