Race/Ethnicity and Changing US Socioeconomic Gradients in Breast Cancer Incidence: California and Massachusetts, 1978–2002 (United States)

Abstract  Objective We tested the hypothesis that the US socioeconomic gradient in breast cancer incidence is declining, with the decline most pronounced among racial/ethnic groups with the highest incidence rates. Methods We geocoded the invasive incident breast cancer cases for three US population-based cancer registries covering: Los Angeles County, CA (1978–1982, 1988–1992, 1998–2002; n = 68,762 cases), the San Francisco Bay Area, CA (1978–1982, 1988–1992, 1998–2002; n = 37,210 cases) and Massachusetts (1988–1992, 1998–2002; n = 48,111 cases), linked the records to census tract area-based socioeconomic measures, and, for each socioeconomic stratum, computed average annual breast cancer incidence rates for the 5-year period straddling the 1980, 1990, and 2000 census, overall and by race/ethnicity and gender.