Abstract
BACKGROUND: We previously demonstrated differences in treatment and mortality between non-Hispanic Black (NHB) and non-Hispanic White (NHW) women with triple-negative breast cancer (TNBC). The impact of residential segregation on TNBC treatment and outcomes remains unknown. METHODS: We identified NHB and NHW women with TNBC diagnosed from 2010 to 2015 and followed through 2016, using the Surveillance, Epidemiology, and End Results dataset. County-level racialized economic segregation was measured using the index of concentration at the extremes. Multilevel Cox regression and multilevel logistic regression accounting for county-level clustering were used to calculate HRs and ORs. RESULTS: Of 25,217 patients, 25.6% were NHB. Compared with patients in counties with the highest concentration of high-income NHW residents (most privileged), patients in counties with the highest concentration of low-income NHB residents (most deprived) had significantly higher risks of breast cancer-specific mortality [HR = 1.14; 95% confidence interval (CI), 1.01-1.30; Ptrend = 0.12], overall mortality (HR = 1.15; 95% CI, 1.02-1.29; Ptrend = 0.06), and late-stage diagnosis (OR = 1.15; 95% CI, 1.01-1.32; Ptrend = 0.03). Overall, 28.2%, 24.5%, and 18.3% of excess risks of breast cancer mortality, overall mortality, and late-stage diagnosis in NHB (vs. NHW) patients were explained by residential segregation. There was no significant association between residential segregation and treatment. CONCLUSIONS: Living in the most deprived versus privileged neighborhoods was associated with lower likelihoods of early detection and survival of patients with TNBC, contributing to TNBC outcome disparities between NHBs and NHWs. IMPACT: This highlights the importance of breast cancer screening for neighborhoods with predominantly low-income NHB residents and elucidating the pathways linking segregation to TNBC prognosis.