Racialized Economic Segregation, Treatment and Outcomes in Women with Triple-Negative Breast Cancer.

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 2010-2015 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 hazard ratios (HRs) and odds ratios (ORs).

Results: Of 25217 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% 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 vs privileged neighborhoods was associated with lower likelihoods of early detection and survival of 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.