Long-Term Safety of Letrozole and Gonadotropin Stimulation for Fertility Preservation in Women With Breast Cancer

There has been increased attention to the issue of fertility preservation (FP). We aimed to investigate the long-term safety of FP via controlled ovarian stimulation with letrozole supplementation (COSTLES) prior to breast cancer treatment.This is a prospective, nonrandomized, controlled study conducted between the years 2002 and 2014. A total of 337 women diagnosed with stage 3 or less invasive breast cancer were enrolled during a FP...