Inequalities in breast cancer incidence and mortality in women with and without disabilities in South Korea: A population-based cohort study.

Objective: Women with disabilities often face functional limitations and comorbidities that increase cancer risk. This study investigated breast cancer incidence and mortality among women with and without disabilities in South Korea. Methods: We analyzed 2.87 million cancer-free women aged ≥30 who participated in the 2002-2003 national health screening program, linking the National Health Insurance Database, Cancer Registry, and cause-of-death records (2003-2019). Standardized incidence ratios (SIRs), standardized mortality ratios (SMRs), and mortality-to-incidence (M/I) ratios were calculated by disability status. Cox proportional hazards models with piecewise follow-up estimated adjusted hazard ratios (aHRs) for breast cancer outcomes. Results: Among 296,689 women with disabilities, 3579 developed breast cancer and 465 died from it; among 2.58 million without disabilities, 46,267 developed it and 3779 died. Women with disabilities had lower incidence (SIR ratio 0.86, 95 % CI 0.83, 0.90) but comparable breast cancer-specific mortality (SMR ratio 1.00, 95 % CI 0.89, 1.13). Cox models showed consistently lower aHRs for breast cancer incidence and mortality early on, but aHRs for all-cause mortality increased over time. Conclusions: Despite lower incidence, women with disabilities experienced similar breast cancer-specific mortality and higher long-term all-cause mortality. These findings underscore persistent inequalities and highlight the need for timely, equitable cancer care.