Breast Cancer Screening and Regional Inequalities: Effects of Pink October in Brazil

Breast cancer is the leading cause of cancer-related deaths among women in Brazil. Early detection through mammography is an effective strategy to reduce mortality; however, access remains unequal across regions. The Pink October campaign, promoted annually by Brazil's Ministry of Health, aims to raise awareness and encourage breast cancer screening. This study evaluates the heterogeneous effects of the Pink October campaign across Brazil's five regions using an interrupted time-series approach with data from 2015 to 2024. We analyzed monthly screening rates among women aged 50 to 69, the target population for biennial mammography. Results indicate a significant increase in screening rates during the campaign period, with notable variation across regions. The Northeast showed the highest relative increase (+57.42%), followed by the South (+29.73%). In contrast, the North and Central-West regions exhibited more modest gains. The regional disparities appear to be associated with differences in primary health care coverage, as the regions with the greatest increases also report higher Family Health Strategy coverage. These findings suggest that national awareness campaigns, while broadly effective, must be complemented by local capacity-building strategies to ensure equitable outcomes. Tailored implementation based on local health system strength can maximize the effectiveness of health promotion efforts and reduce persistent geographic inequalities in access to breast cancer prevention services.