GNRH1 and breast cancer: found that in breast cancer patients undergoing a Controlled Ovarian Stimulation Treatment with Letrozole Supplementation Study protocol [COST-LESS (32)], patients treated with a GnRH agonist trigger had a similar number of total oocytes retrieved as those treated with a hCG trigger (16.4 ± 10.3 versus 12.8 ± 7.7, NS).