According to the Surveillance Epidemiology and End Results (SEER) database, patients aged ≥70 years may be as high as 40% of all breast cancer patients.6 Majority of early-stage invasive BC is estrogen-receptor positive (ER+).7,8 Breast cancer in older women is shown to be more indolent compared with the younger women.9 Here, ESR1 is linked to breast cancer.