Examining the Role of the Social Vulnerability Index in the Association between Race/Ethnicity and Breast Cancer...

Socioeconomic and environmental inequities may increase vulnerability to breast cancer among racial and ethnic groups. We examined whether the social vulnerability index (SVI) mediates associations between race/ethnicity and breast cancer outcomes, including late-stage diagnosis and breast cancer-specific mortality.

We conducted a retrospective analysis of 739,448 cases with breast cancer from the Surveillance, Epidemiology, and End Results 18 registries (2000-2016). Mediation analysis evaluated five 2010 SVI themes-socioeconomic status, household composition, minority status/language, housing/transportation, and overall SVI-in associations between race/ethnicity and breast cancer outcomes among non-Hispanic (NH) Black, NH Asian/Pacific Islander (API), and Hispanic women compared with NH-White cases. Percent mediated quantified the proportion of total effects explained by indirect pathways.

Among NH-Black cases, socioeconomic status theme accounted for 8.6% of the disparity in late-stage diagnosis and 12.9% of the disparity in mortality. Overall social vulnerability theme similarly mediated 6.6% of the disparity in late-stage diagnosis and 9.5% of the Black-White disparity in mortality. For API cases, household composition and minority status/language explained 18.5% and 14.7% of mortality differences, with no significant mediation for late-stage diagnosis. Among Hispanic cases, overall vulnerability mediated 9.1% of the disparity in late-stage diagnosis. For breast cancer mortality, socioeconomic, household composition, and overall SVI themes mediated 31.4%, 17.3%, and 30.4% of the 13% higher mortality risk among Hispanic women compared with NH-White women. Across NH-Black and Hispanic women, higher minority status/language theme was associated with up to a ∼13% lower breast cancer mortality.

Social vulnerability components partially mediated racial and ethnic disparities in breast cancer stage and mortality.

Distinct SVI domains influenced outcomes differently across groups, highlighting the need for structurally focused interventions to reduce disparities in breast cancer outcomes.