Interestingly, although postmenopausal women overall had a reduced risk of breast cancer, in our study, postmenopausal women tended to have late stage breast cancer relative to early stage breast cancer, and were more likely to have HER2‐overexpressing (ER‐, PR−, and HER2+) and triple‐negative subtypes (ER−, PR−, HER2−), the two breast cancer subtypes with worse prognosis.28 Previous studies among Chinese women have examined the associations between menopausal status and various combinations of molecular markers of breast cancer. Here, ESR1 is linked to breast cancer.