Report of the European Society of Mastology Breast Cancer Screening Evaluation Committee

The effect of the Flemish breast cancer screening program on breast cancer-specific mortality: A case-referent study

BACKGROUND

Breast cancer screening programs were introduced in many countries worldwide following randomized controlled trials in the 1980s showing a reduction in breast cancer-specific mortality. However, their effectiveness remains debated and estimates vary. A breast cancer screening program was introduced in 2001 in Flanders, Belgium where high levels of opportunistic screening practices are observed. The effectiveness of this program was estimated by measuring its effect on breast cancer-specific mortality.

METHODS

We performed a case-referent study to investigate the effect of participation in the Flemish population-based mammography screening program (PMSP) on breast cancer-specific mortality from 2005 to 2017. A multiple logistic regression model assessed the association between breast cancer-specific death and screening program participation status in the four years prior to (pseudo)diagnosis (yes/no), with adjustment for potential confounders (individual socio-economic position and calendar year of diagnosis) and stratified for age. In addition, we performed different sensitivity analyses.

RESULTS

We identified 1571 cases and randomly selected 6284 referents. After adjustment, women who participated in PMSP had a 51 % lower risk of breast cancer-specific mortality compared to those who did not (adjusted odds ratio [aOR] =0.49, 95 % CI: 0.44-0.55). Sensitivity analyses did not markedly change the estimated associations. Correction for self-selection bias reduced the effect size, but the estimate remained significant.

CONCLUSION

Our results indicate that in a context of high opportunistic screening rates, participation in breast cancer screening program substantially reduces breast cancer-specific mortality. For policy, these results should be balanced against the potential harms of screening, including overdiagnosis and overtreatment.

Errors in Conduct of the CNBSS Trials of Breast Cancer Screening Observed by Research Personnel

OBJECTIVE

To investigate why the Canadian National Breast Screening Study (CNBSS) did not show mortality reduction with mammography. This study explored long-standing concerns related to the validity of the randomization process, methods of recruiting women to participate in the trials, and training of the staff working in the CNBSS.

METHODS

Surviving former CNBSS personnel, whose roles involved direct recruitment, enrollment, randomization, clinical examination, image interpretation, and management of patients in the CNBSS were interviewed. Individuals were contacted and consented to provide firsthand accounts of daily operations and adherence to research protocols via standardized questions. Consistency of observational data with quantitative results from the CNBSS trials was evaluated.

RESULTS

Eleven of 28 (39.3%) staff confirmed that women with preexisting symptoms of breast cancer were systematically recruited at some centers; 57.1% (16/28) confirmed that personnel performing screening in CNBSS had very limited training and experience; 39.3% (11/28) verified that imaging equipment was often substandard; 50% (14/28) indicated that mammography image quality was generally poor; and 28.6% (8/28) corroborated that in some cases surgeons were unwilling to perform biopsies or surgeries for women with suspicious abnormalities found only on screening mammography that lacked a palpable correlate.

CONCLUSION

These firsthand accounts provide new information confirming that the CNBSS did not consistently and rigorously assess the true efficacy of screening mammography. The staff accounts clarify reasons why the CNBSS results were outliers compared with the six other randomized trials of screening mammography and should not be used as credible scientific evidence to inform health policy.

The First Breast Cancer Screening Program in Southern Italy: Preliminary Results from Three Municipalities of the Naples Province

Aims and Background

It has been demonstrated that breast cancer screening induces a 30% reduction of specific mortality. In May 1990, we started a pilot screening program to assess the feasibility of carrying out such a program in Campania (southern Italy). Herein we report the results of the first round of the program from three municipalities (Giugliano, Mugnano and Qualiano) that lie within the local health district no. 23, close to the city of Naples.

Methods

Women between the ages of 50 and 69 years were sent a personalized letter inviting them to attend the screening test; those not responding were sent a second invitation. The screening test consisted of clinical examination followed by two-view mammography. Second–level diagnostic tools were sonography, fine needle aspiration (manual, echo-guided and stereotaxic) and surgical biopsy.

Results

Out of 5,732 women invited for the first round, 1,813 (31.6%) attended the screening. Attendance rate was higher among younger women. Ninety-one women were positive at the screening test and underwent further examination (recall rate, 5.0%). Among them, 19 had surgical biopsy (biopsy rate, 1.0%) that led to breast cancer diagnosis in 11 cases. The benign/malignant biopsy rate was 0.73. Detection rate was 6.07 × 1,000 screened women and varied among age categories, increasing within the 60–69 subgroup; detection rate/expected incidence ratio in the overall group was 4.5 and also increased within the older age category. Seven out of 11 cancers were at UICC stage 0-I. Among 327 self-referring women, 38 were positive (recall rate, 11.6%), and 14 underwent biopsy (biopsy rate, 4.3%), which showed cancer in 7 cases (benign/malignant biopsy rate, 1.0). In addition, 2 inflammatory cancers were diagnosed without surgical biopsy. Thus 9 cancer cases were detected in this group. Self-referring women differed from responding women in that they had a higher frequency of symptoms or familiar history of cancer, and a higher educational level and awareness of preventive medicine. Clinical examination added no diagnostic advantage in the responding group but did not significantly worsen the recall rate. In the self-referring group, one case of inflammatory cancer was missed by mammography and diagnosed by clinical examination.

Conclusion

The early results (recall rate = 5%, detection rate/expected incidence ratio = 4.5, benign/malignant biopsy rate = 0.73, advanced cancers = 36.4%) are encouraging and indicate the validity of the program. Strategies to improve attendance rate are planned.

The value of modern mammography screening in the control of breast cancer: understanding the underpinnings of the current debates

Since the introduction of mammography screening, debates about the value of screening have endured and been contentious. Recent reviews of the randomized controlled trials reach different conclusions about the absolute benefit of screening, as do evaluations of population trends in breast cancer mortality and the evaluations of service screening. Conclusions about the value of screening commonly are expressed in terms of the balance of benefits and harms, which can differ greatly even when derived seemingly from the same data. It can be shown when different estimates are adjusted to a common screening and follow-up scenario, differences in balance sheet estimates diminish substantially. The strong evidence of benefit associated with exposure to modern mammography screening suggests that it is time to move beyond the randomized controlled trial estimates of benefit and consider policy decisions on the basis of benefits and harms estimated from the evaluation of current screening programs.