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.

Abstract

502 Background: 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 ¡Â45 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 confirmed to be premenopausal at each visit, the patient was randomized to receive 5 years of T (T-only group) or 5 years of T plus 2 years of OFS by monthly goserelin (T + OFS group). A total of 1282 patients was randomly assigned. Disease-free survival was defined as the time from enrollment to the detection of recurrence of breast cancer, contralateral breast cancer, secondary malignancy, or death by any cause. Results: After a median follow-up of 63 months, the estimated disease-free survival rate at 5 years was 91.1% in the T + OFS group and 87.5% in the T-only group (hazard ratio 0.686; 95% confidence interval [CI], 0.483 to 0.972; P = 0.033). The estimated overall survival rate after 5 years was 99.4% in the T + OFS group and 97.8% in the T-only group (hazard ratio 0.310; 95% CI, 0.102 to 0.941; P = 0.029). Conclusions: Ovarian function needs to be monitored for at least 24 months after completing chemotherapy to establish eligibility for OFS. Adding 2 years of OFS to T significantly improved disease-free survival as compared to T alone in those who remained premenopausal or resumed ovarian function after chemotherapy. Clinical trial information: NCT00912548.