Metropolitan area racial residential segregation, neighborhood racial composition, and breast cancer mortality.

PURPOSE: There are significant relationships between racial residential segregation (RRS) and a range of health outcomes, including cancer-related outcomes. This study explores the contribution of metropolitan area RRS, census tract racial composition and breast cancer and all-cause mortality among black and white breast cancer patients.
METHODS: This study has three units of analysis: women diagnosed with breast cancer (n = 22,088), census tracts where they lived at diagnosis (n = 1,373), and the metropolitan statistical area (MSA)/micropolitan statistical area (MiSA) where they lived at diagnosis (n = 37). Neighborhood racial composition was measured as the percent of black residents in the census tract. Metropolitan area RRS was measured using the Information Theory Index. Multilevel Cox proportional hazards models examined the association of metropolitan area RRS and census tract racial composition with breast cancer and all-cause mortality. Survival analysis explored and compared the risk of death in women exposed to environments where a higher and lower proportion of residents were black.
RESULTS: Breast cancer mortality disparities were largest in racially mixed tracts located in high MSA/MiSA segregation areas (RR = 2.06, 95 % CI 1.70, 2.50). For black but not white women, as MSA/MiSA RRS increased, there was an increased risk for breast cancer mortality (HR = 2.20, 95 % CI 1.09, 4.45). For all-cause mortality, MSA/MiSA segregation was not a significant predictor, but increasing tract percent black was associated with increased risk for white but not black women (HR 1.29, 95 % CI 1.05, 1.58).
CONCLUSIONS: Racial residential segregation may influence health for blacks and whites differently. Pathways through which RRS patterns impact health should be further explored.