OBJECTIVES: Structural racism (SR) — macro-level forces that perpetuate racial/ethnic inequities – influences cancer outcomes. Here we assessed several neighborhood SR measures as indicators of racial and economic segregation and examined their concordance as predictors of survival among patients with metastatic breast cancer (mBC).

METHODS: This retrospective study used the nationwide (US-based) Flatiron Health electronic health record-derived de-identified database, focusing on patients diagnosed with mBC from January 2011 to October 2022. Patients were linked to census tract-level data from the American Community Survey. We examined four neighborhood-level SR measures (%Black, Yost Index, Index of Concentration at the Extremes (ICE), and Structural Racism Indicator [SRI]; categorized as population-weighted quintiles, ranging from lowest to highest SR). To assess concordance, we (1) examined real-world overall survival inequities using different SR measures (Cox proportional hazards models adjusted for age, ECOG performance status, and stage); and (2) compared Pearson correlation coefficients between SR measures.

RESULTS: Among a cohort of 22,113 patients (median age: 64), patients from neighborhoods with higher levels of SR (Q1 vs Q5) were disproportionately Black or Latinx regardless of SR measure used. Residing in a neighborhood with higher levels of SR was associated with worse survival (ranging from 23% higher mortality risk [HR:1.23, 95% CI: 1.17-1.30] using the %Black measure to 27% greater risk using the SRI measure [HR: 1.27, 95% CI: 1.20-1.35]). Most SR measures had high positive correlation (r: 0.68-0.87), though %Black and Yost Index had low positive correlation (r: 0.38).

CONCLUSIONS: Most neighborhood measures of SR were highly correlated and all were associated with survival. While choice of neighborhood SR measure should be driven by conceptual considerations, both multidimensional measures like ICE and simple measures like %Black can highlight inequities associated with SR. Efforts to reduce persistent cancer inequities should assess and address neighborhood SR.