The role of area‐level socioeconomic disadvantage in racial disparities in cancer incidence in metropolitan Detroit

BACKGROUND: Neighborhood deprivation is associated with both race and cancer incidence, but there is a need to better understand the effect of structural inequities on racial cancer disparities. The goal of this analysis was to evaluate the relationship between a comprehensive measure of neighborhood‐level social disadvantage and cancer incidence within the racially diverse population of metropolitan Detroit. METHODS: We estimated breast, colorectal, lung, and prostate cancer incidence rates using Metropolitan Detroit Cancer Surveillance System and US decennial census data. Neighborhood socioeconomic disadvantage was measured by the Area Deprivation Index (ADI) using Census Bureau's American Community Survey data at the Public Use Microdata Areas (PUMA) level. Associations between ADI at time of diagnosis and cancer incidence were estimated using Poisson mixed‐effects models adjusting for age and sex. Attenuation of race‐incidence associations by ADI was quantified using the “mediation” package in R. RESULTS: ADI was inversely associated with incidence of breast cancer for both non‐Hispanic White (NHW) and non‐Hispanic Black (NHB) women (NHW: per‐quartile RR = 0.92, 95% CI 0.88–0.96; NHB: per‐quartile RR = 0.94, 95% CI 0.91–0.98) and with prostate cancer incidence only for NHW men (per‐quartile RR = 0.94, 95% CI 0.90–0.97). ADI was positively associated with incidence of lung cancer for NHWs and NHBs (NHW: per‐quartile RR = 1.12, 95% CI 1.04–1.21; NHB: per‐quartile RR = 1.37, 95% CI 1.25–1.51) and incidence of colorectal cancer (CRC) only among NHBs (per‐quartile RR = 1.11, 95% CI 1.02–1.21). ADI significantly attenuated the relationship between race and hormone receptor positive, HER2‐negative breast cancer (proportion attenuated = 8.5%, 95% CI 4.1–16.6%) and CRC cancer (proportion attenuated = 7.3%, 95% CI 3.7 to 12.8%), and there was a significant interaction between race and ADI for lung (interaction RR = 1.22, p < 0.0001) and prostate cancer (interaction RR = 1.09, p = 0.00092). CONCLUSIONS: Area‐level socioeconomic disadvantage is associated with risk of common cancers in a racially diverse population and plays a role in racial differences in cancer incidence.