Abstract
Aromatase inhibitors can be utilized to minimize oestrogen exposure in breast cancer patients undergoing gonadotrophin stimulation. This retrospective-prospective study determined whether using a gonadotrophin-releasing hormone agonist (GnRHa) trigger instead of human chorionic gonadotrophin (HCG) would reduce oestrogen exposure and improve cycle outcomes in aromatase inhibitor cycles. Seventy-four breast cancer patients who desired fertility preservation, with normal ovarian reserve and < 45 years of age received letrozole 5mg/day plus recombinant FSH 150-300 IU/day for ovarian stimulation. Subjects either received HCG 5000-10,000 IU (n=47) or leuprolide acetate 1mg (GnRHa, n=27) as trigger. Oestradiol measurements were repeated 4 days after the trigger and subjects were evaluated for ovarian hyperstimulation syndrome (OHSS). In the GnRHa group, oestradiol concentrations dropped significantly after the trigger than the HCG group (P=0.013) and there was a lower incidence of OHSS. GnRHa trigger resulted in a higher number and percentage of mature oocytes and a higher number of cryopreserved embryos or oocytes compared with HCG. GnRHa trigger improves outcomes by increasing the yield of mature oocytes and embryos in aromatase inhibitor cycles and also decreases the post-trigger oestradiol exposure as well as OHSS risks in women with breast cancer.