Fertility preservation in women with breast cancer

Abstract

Fertility preservation is an important issue for young women diagnosed with breast cancer. The most well-established options for fertility preservation in cancer patients, embryo and oocyte cryopreservation, have not been traditionally offered to breast cancer patients as estradiol rise during standard stimulation protocols may not be safe for those patients. Potentially safer stimulation protocols using tamoxifen and aromatase inhibitors induce lower levels of estradiol whereas similar results in terms of number of oocyte and embryo obtained to standard protocols. Cryopreservation of immature oocytes and ovarian cortical tissue, both still experimental methods, are also fertility preservation options for breast cancer patients.

Figure 1. COST-LESS protocol (Controlled Ovarian Stimulation with Letrozole Supplementation) and GnRHa trigger to reduce estrogen exposure in breast cancer patients

Letrozole starts on the 2^nd day of the cycle and is discontinued the day of trigger. Gonadotropins are initiated on the 4^th day of the cycle. A GnRH antagonist is administered when tle leading follicle has reached 14 mm in size or estradiol levels reach ≥ 250 pg/ml (918 pmol/L). The trigger is induced with a GnRH analogue (GnRHa) administered when at least two follicles have reached 20 mm in diameter. Letrozole is reinitiated after egg retrieval and continued until estradiol levels fall below 50 pg/ml (183 pmol/L).