Racialized Economic Segregation and Breast Cancer Mortality among Women in Maryland

Background: Our objective was to determine the association between racialized economic segregation and the hazard of breast cancer mortality in Maryland. Methods: Among 35,066 women (24,540 White; 10,526 Black) diagnosed with incident invasive breast cancer in Maryland during 2007 to 2017, exposure to racialized economic segregation was measured at the census tract level using Index of Concentration at the Extremes metrics. HRs and 95% confidence intervals (CI) were estimated using Cox proportional hazards regression for the association between racialized economic segregation and the hazard of breast cancer mortality, accounting for clustering at the census tract level. Models were adjusted for age and stratified by race, median age (<60 years, ≥60 years), and clinical characteristics. Results: Overall, the hazard of breast cancer mortality was 1.84 times as high (95% CI, 1.64–2.06) for the least privileged quintile of racialized economic segregation compared with the most privileged quintile. This association differed significantly (P_interaction< 0.05) by race and age, with 1.20 (95% CI, 0.90–1.60) times the hazard of breast cancer mortality for Black women versus 1.66 (95% CI, 1.41–1.95) times the hazard for White women, and with greater hazards for younger women (HR, 2.17; 95% CI, 1.83–2.57) than older women (HR, 1.62; 95% CI, 1.40–1.88). Conclusions: Our results suggest that breast cancer survival disparities exist in Maryland among women residing in the least privileged census tracts with lower income households and higher proportions of Black residents. Impact: Our findings provide new insights into the breast cancer mortality disparities observed among women in Maryland.