Neighborhood Disadvantage and Breast Cancer-Specific Survival in the US.

Importance: Despite improvements in breast cancer screening, treatment, and survival, disparate breast cancer-specific survival outcomes persist, particularly in disadvantaged neighborhoods. Most of these disparities are attributed to disparities in individual, tumor, and treatment characteristics. However, a critical knowledge gap exists as to whether disparities in breast cancer-specific survival remain after accounting for individual, tumor, and treatment characteristics. Objective: To evaluate if neighborhood disadvantage is associated with shorter breast cancer-specific survival after controlling for individual, tumor, and treatment characteristics in a national population. Design, Setting, and Participants: This national retrospective cohort study included patients with breast cancer diagnosed from 2013 to 2018 from the Surveillance, Epidemiology, and End Results 17 Census tract-level socioeconomic status and rurality database of the National Cancer Institute. Data analysis was performed from September 2022 to December 2023. Exposures: Neighborhood disadvantage measured by Yost index quintiles. Main Outcomes and Measures: Breast cancer-specific survival was evaluated using a competing risks cause-specific hazard model controlling for age, race, ethnicity, rurality, stage, subtype, insurance, and receipt of treatment. Results: A total of 350 824 patients with breast cancer were included; 41 519 (11.8%) were Hispanic, 39 631 (11.3%) were non-Hispanic Black, and 234 698 (66.9%) were non-Hispanic White. A total of 87 635 patients (25.0%) lived in the most advantaged neighborhoods (group 5) and 52 439 (14.9%) lived in the most disadvantaged neighborhoods (group 1). A larger number of non-Hispanic White patients (66 529 patients [76.2%]) lived in advantaged neighborhoods, while disadvantaged neighborhoods had the highest proportion of non-Hispanic Black (16 141 patients [30.9%]) and Hispanic patients (10 168 patients [19.5%]). Breast cancer-specific survival analysis found the most disadvantaged neighborhoods (group 1) had the highest risk of mortality (hazard ratio, 1.43; 95% CI, 1.36-1.50; P < .001) compared with the most advantaged neighborhoods. Conclusions and Relevance: In this national cohort study of patients with breast cancer, neighborhood disadvantage was independently associated with shorter breast cancer-specific survival even after controlling for individual-level factors, tumor characteristics, and treatment. This suggests potential unaccounted-for mechanisms, including both nonbiologic factors and biologic factors.