Beta coefficients for the association between body mass index ≥ 30kg/m2 and breast cancer after accounting for possible mediation by estradiol, insulin, and/or C-reactive protein (CRP) among non-HT users at baseline. Vertical lines represent the 95% confidence intervals. Base model adjusted for age, race/ethnicity, alcohol consumption, family history of breast cancer, parity, years of menstrual cycling, age at first child’s birth, history of benign breast disease, and physical activity.