Cardiometabolic Health and Risk of Breast Cancer Subtypes Among US Black Women

) was associated with increased risks of ER+ (HR = 1.35, 95% CI = 1.15-1.59) breast cancer and the luminal A-like subtype (HR = 1.54, 95% CI = 1.19-1.98). No other cardiometabolic factors were associated with breast cancer subtypes. Relative to those with no cardiometabolic factors, postmenopausal women with ≥ 3 cardiometabolic conditions had a 43% higher risk of ER+ cancer (95% CI = 1.04-1.97) and a 38% lower risk of ER- cancer (95% CI = 0.37-1.02; p-heterogeneity = 0.006). Analyses of all possible combinations of 2 or 3 factors resulted in HRs > 1.0 for analyses of ER+ breast cancer and HRs not significantly different from 1.0 for analyses of ER- breast cancer. There were no statistically significant findings among premenopausal women. In this large cohort of Black women, poorer cardiometabolic health was associated with higher ER+ and lower ER- breast cancer risk among postmenopausal women. These divergent associations support a role for metabolic-endocrine crosstalk in breast cancer etiology.