ESR1 and breast cancer: Other options besides chemical ovarian suppression are surgical oophorectomy and radiation-induced ovarian ablation which cause irreversible menopause, making it a less suitable option for relatively young premenopausal patients. Selective estrogen receptor modulators (SERM) have been used for the longest time in premenopausal women for the treatment of estrogen-positive breast cancer. In 2003, SOFT and TEXT studies were done to determine the superiority of adding ovarian suppression to tamoxifen as well as to establish the role of AIs plus ovarian suppression [7,8].