Structural Racism and Breast Cancer-specific Survival: Impact of Economic and Racial Residential Segregation

Abstract

Objective: To analyze the effect of economic and racial/ethnic residential segregation on breast cancer-specific survival (BCSS) in South Florida, a diverse metropolitan area that mirrors the projected demographics of many United States regions.

Summary background data: Despite advances in diagnosis and treatment, racial and economic disparities in BCSS. This study evaluates these disparities through the lens of racial and economic residential segregation, which approximate the impact of structural racism.

Methods: Retrospective cohort study of stage I to IV breast cancer patients treated at our institution from 2005 to 2017. Our exposures include index of concentration at the extremes, a measurement of economic and racial neighborhood segregation, which was computed at the census-tract level using American Community Survey data. The primary outcome was BCSS.

Results: Random effects frailty models predicted that patients living in low-income neighborhoods had higher mortality compared to those living in high-income neighborhoods [hazard ratios (HR): 1.56, 95% confidence interval (CI): 1.23-2.00]. Patients living in low-income non-Hispanic Black and Hispanic neighborhoods had higher mortality compared to those living in high-income non-Hispanic White (NHW) neighborhoods (HR: 2.43, 95%CI: 1.72, 3.43) and (HR: 1.99, 95%CI: 1.39, 2.84), after controlling for patient characteristics, respectively. In adjusted race-stratified analysis, NHWs living in low-income non-Hispanic Black neighborhoods had higher mortality compared to NHWs living in high-income NHW neighborhoods (HR: 4.09, 95%CI: 2.34-7.06).

Conclusions: Extreme racial/ethnic and economic segregation were associated with lower BCSS. We add novel insight regarding NHW and Hispanics to a growing body of literature that demonstrate how the ecological effects of structural racism-expressed through poverty and residential segregation-shape cancer survival.

Figure 1:. Census Tract-Level Index of Concentration at the Extremes (ICE)^a in Miami-Dade County, Florida.

Caption: A) Non-Hispanic Black, (B) Hispanic, (C) Income, (D) Non-Hispanic Black racialized economic segregation, and (E) Hispanic racialized economic segregation. The most privileged and/or most NHW tracts appear in the darkest blue tones, and the least privileged and/or most NHB and Hispanic tracts appear in the darkest red tones. ^a ICE ranges from −1, where all households are considered marginalized, to 1, where all households are considered privileged.