Abstract
BACKGROUND: Biennial breast screening enables timely diagnosis, a critical determinant of survival. However, this benefit depends on navigating complex healthcare systems where immigrant women often encounter barriers. We posed the question of whether immigrant women in Ontario experience a “double burden” of lower screening adherence and prolonged intervals between clinical presentation and confirmed diagnosis compared to long-term residents. METHODS: We identified women aged 50–74 eligible for breast screening in provincial administrative databases. We calculated the proportion up-to-date with biennial mammography annually (2012–2020) and modelled the incidence rate ratio (IRR) using negative binomial regression, adjusting for age, marginalization, and morbidity. Additionally, we identified women with a first breast cancer diagnosis and matched each immigrant 1:2 to long-term residents by age, stage, and year of diagnosis. The time from first clinical presentation to diagnosis was analyzed using adjusted linear regression and conditional logistic regression. RESULTS: On January 1, 2020, 59.9% of long-term residents were up-to-date with screening compared to 51.4% of immigrants (adjusted IRR 0.74; 95% CI 0.71–0.78). The adjusted mean time to diagnosis was 1.21 days longer for immigrants (95% CI 0.10–2.32), a clinically negligible difference. However, diagnostic delays were systemic: 25% of all women waited ≥ 60 days, and 10% waited ≥ 135 days, with no significant difference between groups. Immigrants were more likely to be diagnosed at Stage 2 or 3 compared to long-term residents (51.7% vs. 46.6%, p < 0.001). CONCLUSION: Comprehensive process mapping of screening and diagnostic processes is required involving representatives of all stakeholders and all subpopulations eligible for breast screening, in order to conduct and implement knowledge-based revisions of screening and BC diagnosis service delivery in Ontario, improve the uptake of screening and the BC stage distribution among immigrant women, and reduce lengthy diagnostic delays.