Role of adding ovarian function suppression to tamoxifen in young women with hormone-sensitive breast cancer who remain premenopausal or resume menstruation after chemotherapy: The ASTRRA study.

502Background: The role of adding ovarian function suppression (OFS) to tamoxifen (T) for premenopausal patients with breast cancer after completing (neo) adjuvant chemotherapy is uncertain. The prospective randomized phase III trial was conducted to evaluate the efficacy of adding OFS to T in patients with hormone receptor-positive breast cancer who remain in premenopausal status or resume ovarian function after chemotherapy (NCT00912548). The primary and key secondary endpoints were to compare the 5-year disease-free survival and overall survival, respectively, between patients who received T and those who received T and OFS. Methods: We enrolled 1483 premenopausal women (aged iÂ45 years) with estrogen receptor-positive breast cancer who were treated with definitive surgery after completing neoadjuvant or adjuvant chemotherapy. Ovarian function was assessed every 6 months for 2 years since enrollment based on follicular-stimulating hormone levels and menstruation history. If ovarian function was confirm...