The effect of the Flemish breast cancer screening program on breast cancer-specific mortality: A case-referent study. (February 2023)

• Record Type: Journal Article
• Authors: De Troeyer, Katrien; Silversmit, Geert; Rosskamp, Michael; Truyen, Inge; Van Herck, Koen; Goossens, Mathijs Michiel; Martens, Patrick; Kellen, Eliane; Hendrickx, Erik; Rummens, Elise; De Smet, Frank; Broeders, Mireille; Verdoodt, Freija; De Schutter, Harlinde
• Is Part Of: Cancer epidemiology. Volume 82(2023)
• Publication Date: 2023-02
• Subjects: PMSP population-based mammography screening program -- CvKO Centre for Cancer Detection (Centrum voor Kankeropsporing) -- BCR Belgian Cancer Registry -- IMA InterMutualistic Agency -- AVIQ Agence pour une VIe de Qualité -- RR1 estimated intention-to-treat effect of invitation to screening -- RR2 estimated effect of offering screening to those who would participate if invited -- Dr mortality from the disease in non-participants compared with uninvited controls (estimated from European studies) -- p attendance rate -- φ odds ratio -- OR odds ratio (aOR, adjusted odds ratio) -- CI confidence interval -- IQR interquartile range; Breast cancer -- Mass screening -- Mortality -- Case-control studies -- Belgium; Cancer -- Epidemiology -- Periodicals; Cancer -- Prevention -- Periodicals; Cancer -- Diagnosis -- Periodicals; Carcinogenesis -- Periodicals; 616.994005
• DOI: 10.1016/j.canep.2022.102320
• Languages: English
• ISSNs: 1877-7821

Abstract

Abstract: 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. Highlights: Evaluation screening program in Flanders with high opportunistic mammography rate. Mammography screening program substantially reduces breast cancer death in Flanders. Results were robust over provinces and to correction for additional confounders. Reduced effect size remained significant after correction for self-selection bias.