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BACKGROUND: Scant research has analyzed contemporary US cancer incidence rates in relation to historical redlining (ie, 1930s US federally imposed residential segregation), implemented via the color-coded federal Home Owners' Loan Corporation (HOLC) maps. METHODS: We analyzed Massachusetts Cancer Registry data for all patients with primary invasive breast cancer (BC) diagnosed in 2005-2015 among women in the 28 Massachusetts municipalities with digitized 1930s HOLC maps. Multilevel Poisson regression estimated BC incidence rate ratios (IRR), overall and by tumor estrogen receptor (ER-positive, ER-negative) and progesterone receptor (PR-positive, PR-negative) status, in relation to HOLC grade and contemporary census tract (CT) social characteristics. RESULTS: Net of age and racialized group, the extremes of BC incidence were detected by combinations of HOLC grade and contemporary CT racialized economic segregation. Compared with CTs with the best HOLC grade (A + B) and most privileged contemporary characteristics (T1), for all, ER-positive and PR-positive BC, incidence was highest in T1 and mixed HOLC grade CTs (eg, IRRER+; Mixed-T1 = 1.10, 95% confidence interval CI = 1.01 to 1.21) and lowest in CTs with most concentrated racialized economic deprivation (T3) and no HOLC grade (eg, IRRER+; No Grade-T3 = 0.85, 95% CI = 0.75 to 0.95). For ER-negative and PR-negative BC, incidence was highest in CTs with the most contemporary deprivation, but the best HOLC grade (eg, IRRER-; A+B-T3 = 1.27, 95% CI = 0.93 to 1.75) and lowest in T1 and worst HOLC-graded CTs (eg, IRRER-; D-T1 = 0.84, 95% CI = 0.56 to 1.25). CONCLUSION: Breast cancer risk may be shaped by combined histories of redlining and present-day CT characteristics.
Wright et al. (Tue,) studied this question.