Long-term comparisons of the efficacy, safety, and pregnancy outcomes of adjuvant tamoxifen plus ovarian function suppression in premenopausal Han and Zhuang Chinese patients with hormone receptor-positive early breast cancer

Objective To compare the efficacy, safety, and pregnancy outcomes of tamoxifen plus ovarian function suppression (OFS) between Han and Zhuang women with hormone receptor-positive breast cancer. Methods A total of 236 Han and 101 Zhuang women with hormone receptor-positive breast cancer who received tamoxifen plus OFS were analyzed retrospectively. Long-term disease-free survival (DFS) and overall survival (OS) were evaluated by Kaplan-Meier analysis, and adverse events and pregnancy outcomes were assessed by chi(2) and Fisher's exact-probability tests. Results There was no significant difference in DFS or OS between Han and Zhuang women (5-year DFS 74.57% and 77.23%, OS 85.59% and 90.01%, respectively). The incidences of endometrial hyperplasia, ovarian cysts, nausea and vomiting, fatty liver, retinitis, and thrombocytopenic purpura were similar in both groups, but Zhuang women had significantly more allergic reactions (6.93% vs. 2.12%). Pregnancy rates among women who attempted pregnancy were similar (Han, 7/138, 5.07%; Zhuang, 2/46, 4.35%). Conclusions OFS plus tamoxifen resulted in similar DFS and OS among premenopausal Han and Zhuang women with hormone receptor-positive breast cancer. However, Zhuang women were more likely to experience an allergic reaction. For women with fertility concerns, OFS plus tamoxifen was associated with similar pregnancy rates in Zhuang and Han women.