Historical Redlining and Breast Cancer Treatment and Survival among older Women in the US.

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 US.

METHODS: Home Owners' Loan Corporation (HOLC) boundaries were used to measure historical redlining. Eligible women in the 2010-2017 SEER-Medicare BC Cohort were assigned an HOLC grade. The independent variable was a dichotomized HOLC grade: A/B (non-redlined), and C/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 residing in HRAs (43.4% vs 37.8%). Historical redlining significantly predicted poorer survival after BC diagnosis; HR [95%CI] = 1.09 [1.03-1.15] for ACM, and 1.26 [1.13-1.41] for BCSM. Indirect effects via comorbidity were identified. Historical redlining was associated with a lower likelihood of receiving surgery; OR [95%CI] = 0.74 [0.66-0.83], and a higher likelihood of receiving palliative care OR [95%CI] = 1.41 [1.04-1.91].

CONCLUSION: Historical redlining is associated with differential treatment receipt and poorer survival for ACM and BCSM. Relevant stakeholders should consider historical contexts when designing/implementing equity-focused interventions to reduce BC disparities. Clinicians should advocate for healthier neighborhoods while providing care.