Abstract P5-12-08: Time course of changes in serum FSH, serum estradiol, and menstruation in premenopausal patients with breast cancer taking tamoxifen after completing chemotherapy: A report from the ASTRRA study

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Abstract BACKGROUND Ovarian suppression with tamoxifen after chemotherapy is a promising therapeutic approach, particularly in young, high-risk breast cancer patients. Assessment of restoration of ovarian function is important with respect to the initiation of ovarian suppression. METHODS In total, 1289 women who remained or resumed premenopausal status after chemotherapy were randomized to receive 5 years of tamoxifen or 5 years of tamoxifen plus 2 years of ovarian suppression. Prospectively collected hormone data were available for 24 months after completing chemotherapy for 267 breast cancer patients without ovarian suppression. RESULTS At 6 months, a premenopausal status was identified in 56.6%, 36%, and 16.2% of patients using serum FSH, E2, and with menstruation bleeding, respectively, and about 30% more women achieved ovarian restoration using all three parameters during the 24-month follow-up. Ovarian function restoration differed significantly according to age group (log-rank, P<0.001 for all definitions). At 6 months, the distribution of patients according to hormone levels was as follows: group 1 (FSH <30 mIU/ml, E2 >20 pg/ml), 28.0%; group 2 (FSH <30 mIU/ml, E2 ≤20 pg/ml), 28.4%; group 3 (FSH ≥30 mIU/ml, E2 >20 pg/ml), 8.0%; and group 4 (FSH ≥30 mIU/ml, E2 ≤20 pg/ml), 35.6%. During the 24-month follow-up, the prevalence of menstruation restoration was higher in group 1 (71.6%) than in the other three groups. Restoration of serum E2 and menstrual bleeding occurred in 44% and 33% of patients in group 2, respectively; the corresponding percentages in group 4 were 40.6% and 28.7% (P<0.001). CONCLUSIONS Ovarian function should be monitored using serum FSH, serum E2, and menstruation history for at least 24 months after completing chemotherapy during tamoxifen treatment to establish eligibility for ovarian suppression. Citation Format: Kim HJ, Ahn SH, Nam SJ, Park SH, Ro JS, Im SA, Jung YS, Noh WC. Time course of changes in serum FSH, serum estradiol, and menstruation in premenopausal patients with breast cancer taking tamoxifen after completing chemotherapy: A report from the ASTRRA study. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-12-08.