Neighborhood Disadvantage, Individual Experiences of Racism, and Breast Cancer Survival.

Importance: Due to the legacy of structural racism in the United States, Black US residents are more likely to live in disadvantaged neighborhoods regardless of individual socioeconomic status. Black women are also more likely to die from their breast cancer. Objective: To investigate whether neighborhood disadvantage and individual experiences of racism are associated with breast cancer mortality among Black US women. Design, Setting, and Participants: Prospective follow-up study conducted within the Black Women's Health Study (BWHS), a nationwide cohort study of 59 000 self-identified Black females enrolled in 1995 and followed up by biennial questionnaires. BWHS participants diagnosed with breast cancer at stages I to III and who survived 12 months after initial diagnosis were included (n = 2290). Deaths and cause of death were identified through linkage with the National Death Index. Exposures: Geocoded participant addresses were linked with US Census Bureau and American Community Survey data to create neighborhood-level indices reflecting relative disadvantage. Data on experiences of racism were obtained from questionnaires. Main Outcomes and Measures: Breast cancer-specific and all-cause mortality. Hazard ratios (HRs) and 95% CIs were estimated from multivariable Cox proportional hazards regression models. Results: There were 305 breast cancer-specific deaths among 2290 women with invasive breast cancer (mean [SD] age at diagnosis, 56.7 [10.9] years) who were followed up for a median (IQR) of 10.5 (5.6-16.1) years. The mortality rate was 14.26 (95% CI, 11.01-17.51) per 1000 person-years for those living in the most disadvantaged neighborhoods and 8.82 (95% CI, 6.55-11.09) per 1000 person-years for those living in the least disadvantaged neighborhoods (HR, 1.47; 95% CI, 1.02-2.12). HRs for women living in areas of extreme economic deprivation (vs privilege) and for women who reported experiences of racism in at least 2 institutional spheres (vs none) were also greater than 1, but not statistically significant (extreme economic deprivation vs privilege: HR, 1.19; 95% CI, 0.88-1.61; racism in 2 spheres vs none: HR, 1.28; 95% CI, 0.96-1.73). Conclusions and Relevance: In this cohort of Black women, living in disadvantaged neighborhoods was associated with a higher mortality from breast cancer, even after accounting for stage at diagnosis, treatments, and individual-level lifestyle factors. Community-level interventions to reduce environmental stressors and improve conditions in disadvantaged neighborhoods, including access to high-quality cancer care, may be critical to reducing racial disparities in breast cancer survival.