In comparison with premenopausal women who had a low BMI (less than 25 kg/m2), the OR among premenopausal women in the highest BMI category (at least 35 kg/m2) was 0.58 (95% CI 0.34 to 1.00) for ER+PR+ breast cancer and 1.07 (95% CI 0.58 to 1.97) for ER- PR- breast cancer. Here, ESR1 is linked to breast cancer.