Historical redlining, breast cancer survival, and the mediating and modifying role of contemporary neighborhood socioeconomic conditions

Historical redlining, a 1930s residential segregation policy, has been associated with contemporary breast cancer survival, but the role of contemporary neighborhood socioeconomic condition is unclear. We investigated mediating and modifying effects of neighborhood socioeconomic condition. This New York State Cancer Registry-based cohort included 60,773 invasive breast cancer cases. Cases were assigned a historical redlining grade (A-D) through linkage to residential census tract at diagnosis. We used labor class index of concentration at the extremes to proxy neighborhood socioeconomic condition. Four-way decomposition evaluated mediation and modification of neighborhood socioeconomic condition on redlining and breast cancer survival. The total effect (risk ratio, RR) on 5-year mortality from D-grade vs. A-grade =1.20 (95% CI: 1.09, 1.31), which decomposed to a controlled direct effect excess RR (ERR)=0.10 (95% CI: -0.01, 0.21) and a pure indirect effect ERR=0.09 (95% CI: 0.05, 0.13); significant interaction was not detected. Results were consistent among hormone receptor+, local-, and regional-stage tumors, but not HR- or distant-stage tumors. Decomposition differs by race/ethnicity. Contemporary neighborhood socioeconomic condition mediates approximately half the association between historical redlining and all-cause breast cancer survival, while the other half is attributed to historical redlining. Interventions addressing neighborhood socioeconomic condition may attenuate redlining-based breast cancer survival disparities.