High yield of oocytes without an increase in circulating estradiol levels in breast cancer patients treated with follicle-stimulating hormone and aromatase inhibitor in standard gonadotropin-releasing hormone analogue protocols.

BACKGROUND Adjuvant/neoadjuvant chemotherapy in breast cancer patients may be associated with amenorrhea and a marked reduction in ovarian reserve. OBJECTIVES To assess the use of letrozole with follicle-stimulating hormone (FSH) in gonadotropin-releasing hormone (GnRH) analogue protocols, based on reported attempts to avoid the estradiol (E2) increase during controlled ovarian hyperstimulation for embryo cryopreservation in breast cancer patients using a combination of low dose FSH and aromatase inhibitor (letrozole) in a GnRH-antagonist protocol. METHODS Twenty-four breast cancer patients were treated with recombinant FSH (150-450 U/day) and letrozole (5 mg/day) in a long GnRH-agonist (n=7) or GnRH-antagonist (n=17) protocol. After oocyte retrieval, insemination and/ or intracytoplasmic sperm injection was performed. The embryos were frozen. RESULTS The average interval from surgery to oocyte retrieval was 40 days. Average duration of treatment was 9.6 days and mean peak E2 level 1342 +/- 1091 pmol/L, yielding 16.0 +/- 16.3 oocytes (range 0-82). Mean fertilization rate was 69.5 +/- 20.4% and mean number of embryos cryopreserved 10.3 +/- 9.3. More oocytes were retrieved with the long GnRH protocol, but the difference was not statistically significant (24.8 +/- 24.6 vs. 12.0 +/- 8.8 pmol/L, P = 0.07). CONCLUSIONS As previously reported, ovarian stimulation with letrozole and FSH, in both the long GnRH-agonist and GnRH-antagonist protocols, is apparently effective in breast cancer patients and spares them exposure to high E2 levels.