Impact of a programme of mass mammography screening for breast cancer on socio-economic variation in survival: a population-based study

BACKGROUND: After a systematic mass mammography breast cancer screening programme was implemented between 1991 and 1996 (attendance 80%), we evaluated its impact on survival according to socioeconomic status (SES). METHODS: We studied survival rates up to 1-1-2005 for all consecutive breast cancer patients aged 50–69 and diagnosed in the period 1983–2002 in the area of the Eindhoven Cancer Registry (n = 4939). Multivariate analyses were performed using Cox regression analysis. RESULTS: The proportion of breast cancer patients with a low SES decreased from 22% in 1983–1990 to 14% in 1997–2002 when attendance was 85%. The proportion of newly diagnosed patients with stage III or IV disease in 1997–2002 was only 10% compared to 14% in 1991–1996 and 26% in 1983–1989 (P < 0.0001). Stage distribution improved for all socio-economic groups (P = 0.01). Survival was similar for all socio-economic groups in 1983–1990, but after the introduction of the screening programme women with low SES had lower age- and stage-adjusted survival rates (HR 2.0, 95%CI: 1.3–3.0). Survival was better for patients diagnosed in 1997–2002 compared to 1983–1990 for all socioeconomic strata; it was substantially better for the high SES group (HR 0.36, 0.2–0.5) compared to the lowest SES (HR 0.77, 0.6–1.1). CONCLUSION: Although survival improved for women from each of the socio-economic strata, related to the high participation rate of the screening programme, women from lower socio-economic strata clearly benefited less from the breast cancer screening programme. That is also related to the higher prevalence of comorbidity and possibly suboptimal treatment.