Historical redlining and breast cancer treatment and survival among older women in the United States.

BACKGROUND: Breast cancer (BC) is the most common cancer among US women, and institutional racism is a critical cause of health disparities. We investigated impacts of historical redlining on BC treatment receipt and survival in the United States. METHODS: Home Owners' Loan Corporation (HOLC) boundaries were used to measure historical redlining. Eligible women in the 2010-2017 Surveillance, Epidemiology, and End Results-Medicare BC cohort were assigned a HOLC grade. The independent variable was a dichotomized HOLC grade: A and B (nonredlined) and C and D (redlined). Outcomes of receipt of various cancer treatments, all-cause mortality (ACM), and BC-specific mortality (BCSM) were analyzed using logistic or Cox models. Indirect effects by comorbidity were examined. RESULTS: Among 18 119 women, 65.7% resided in historically redlined areas (HRAs), and 32.6% were deceased at a median follow-up of 58 months. A larger proportion of deceased women resided in HRAs (34.5% vs 30.0%). Of all deceased women, 41.6% died of BC; a larger proportion resided in HRAs (43.4% vs 37.8%). Historical redlining is a statistically significant predictor of poorer survival after BC diagnosis (hazard ratio = 1.09, 95% confidence interval [CI] = 1.03 to 1.15 for ACM, and hazard ratio = 1.26, 95% CI = 1.13 to 1.41 for BCSM). Indirect effects via comorbidity were identified. Historical redlining was associated with a lower likelihood of receiving surgery (odds ratio = 0.74, 95% CI = 0.66 to 0.83, and a higher likelihood of receiving palliative care odds ratio = 1.41, 95% CI = 1.04 to 1.91). CONCLUSION: Historical redlining is associated with differential treatment receipt and poorer survival for ACM and BCSM. Relevant stakeholders should consider historical contexts when designing and implementing equity-focused interventions to reduce BC disparities. Clinicians should advocate for healthier neighborhoods while providing care.