Post-breast cancer diagnosis screening mammography among First Nations and non-First Nations women in Ontario

OBJECTIVES: First Nations women in Canada have historically experienced lower breast cancer screening participation and worse outcomes than non-First Nations women. While most research has focused on pre-diagnosis screening, less is known about follow-up care. This study examined post-diagnosis mammography use among First Nations and non-First Nations women in Ontario and identified factors associated with follow-up screening among First Nations women. METHODS: This retrospective cohort study included 190 First Nations and 506 non-First Nations women diagnosed with invasive breast cancer between 1995 and 2004, with follow-up screening data available through 2019. Descriptive statistics compared demographic, clinical, and treatment characteristics. Logistic regression models were used among First Nations women to identify factors associated with follow-up screening. RESULTS: No statistically significant differences were observed in the unadjusted comparisons of post-treatment screening rates, frequency, timing, and intervals between First Nations and non-First Nations women. Among First Nations women, older age (OR = 0.42; 95% CI, 0.19-0.94), rural residence (OR = 0.35; 95% CI, 0.17-0.73), and lower income (OR = 0.20; 95% CI, 0.06-0.69) were among the factors associated with reduced screening. Radiotherapy (OR = 7.48; 95% CI, 3.38-16.56) and less severe surgery (OR = 7.19; 95% CI, 3.31-15.63) were associated with higher odds of screening. CONCLUSION: While screening rates among First Nations women are improving, disparities persist. Strengthening continuity of care, primary care access, and culturally safe survivorship support is essential to achieving equity.