Jim Crow and estrogen-receptor-negative breast cancer: US-born black and white non-Hispanic women, 1992–2012

Abstract

Purpose: It is unknown whether Jim Crow—i.e., legal racial discrimination practiced by 21 US states and the District of Columbia and outlawed by the US Civil Rights Act in 1964—affects US cancer outcomes. We hypothesized that Jim Crow birthplace would be associated with higher risk of estrogen-receptor-negative (ER−) breast tumors among US black, but not white, women and also a higher black versus white risk for ER− tumors. Methods: We analyzed data from the SEER 13 registry group (excluding Alaska) for 47,157 US-born black non-Hispanic and 348,514 US-born white non-Hispanic women, aged 25–84 inclusive, diagnosed with primary invasive breast cancer between 1 January 1992 and 31 December 2012. Results: Jim Crow birthplace was associated with increased odds of ER− breast cancer only among the black, not white women, with the effect strongest for women born before 1965. Among black women, the odds ratio (OR) for an ER− tumor, comparing women born in a Jim Crow versus not Jim Crow state, equaled 1.09 (95% confidence interval [CI] 1.06, 1.13), on par with the OR comparing women in the worst versus best census tract socioeconomic quintiles (1.15; 95% CI 1.07, 1.23). The black versus white OR for ER− was higher among women born in Jim Crow versus non-Jim Crow states (1.41 [95% CI 1.13, 1.46] vs. 1.27 [95% CI 1.24, 1.31]). Conclusions: The unique Jim Crow effect for US black women for breast cancer ER status underscores why analysis of racial/ethnic inequities must be historically contextualized.