Is letrozole needed for controlled ovarian stimulation in patients with estrogen receptor-positive breast cancer?

AbstractObjective: To assess the advantages and disadvantages of using Letrozole for controlled ovarian stimulation (COH) in young patients with estrogen receptor-positive (ER+) breast cancer, wishing to cryopreserve oocytes.Design: Retrospective cohort analysis.Setting: Sixteen Italian units for reproductive medicine and in vitro fertilization.Methods: Data of 50 ER+ breast cancer patients undergoing COH to cryopreserve oocytes before gonadotoxic chemotherapy with a Letrozole plus gonadotropins (Le+Gn) protocol were compared with those of 25 young women with ER– breast cancer, submitted to COH using a protocol with gonadotropins alone (Gn-only).Results: The Le+Gn protocol implied a significantly lower total Gn consumption and allowed to maintain significantly lower circulating E2 levels at all checkpoints throughout stimulation (peak E2 value 446 ± 357 versus 1553 ± 908 pg/ml, respectively; p = 0.001). On the other side, the Le+Gn protocol allowed a significantly lower yield of oocytes available for cryo...