Structural Determinants of Racial Disparities in Breast Cancer Survival in Alabama

Despite improvements in breast cancer survival, Black versus White women remain at higher risk of death. Exploring reasons behind this disparity is necessary to facilitate interventions. This study evaluated rural-urban residence and/or area deprivation index (ADI) as mediators of the association between race and survival in adults with breast cancer in Alabama.

This retrospective, population-based cohort included 25,195 adult Black or White women with incident breast cancer in Alabama between January 1, 2010, and December 31, 2019. Exposure was self-reported race; mediators were rural-urban status (Rural-Urban Commuting Area codes) and neighborhood deprivation (state-level ADI). The outcome was overall survival from diagnosis to death (any cause) or end of follow-up (December 31, 2021).

White women (n = 18,749) were older at diagnosis (62.4 vs. 58.7; P < 0.001), had fewer deaths (21.6% vs. 25.8%; P < 0.001), longer follow-up (70.2 vs. 66.7 months; P < 0.001), lower ADI (4.1 vs. 6.3; P < 0.001), and more rural dwellers (23.2% vs. 18.3%; P < 0.001) compared with Black women (n = 6,446). After full adjustment with rural-urban status and ADI as mediators, there was partial mediation of the race-survival effect [direct effect: hazard ratio = 1.14; 95% confidence interval (CI), 1.06-1.22; indirect effect: hazard ratio = 1.10; 95% CI, 1.07-1.12; and proportion mediated: hazard ratio = 0.45; 95% CI, 0.31-0.64]. These results mirrored the model with ADI as the only mediator, indicating that ADI and not rural-urban status drove the indirect effect.

Among Black and White Alabamian women with breast cancer, 45% of the survival disparity is mediated by differences in neighborhood deprivation.

Almost half of the Black-White difference in breast cancer mortality would be eliminated if differences in neighborhood deprivation were improved. See related commentary by Pinheiro and Reeder-Hayes, p. 1683.