Safety of pregnancy after letrozole-FSH stimulation in breast cancer patients: a prospective comparison of frozen embryo transfer to self vs. gestational carriers

Abstract

Ovarian stimulation with aromatase inhibitor letrozole along with FSH has been suggested as a safe and efficient for women with breast cancer (BCa) undergoing oocyte or embryo cryopreservation for fertility preservation. However, cancer recurrence rates among those who successfully conceived have not been reported with this protocol to this date and some still consider gestational carriers (GC) to avoid risk. Our objective was to compare the outcomes and safety of pregnancy after frozen embryo transfer (FET) to self (ST) vs. GC. Prospective. 143 women with BCa ≤Stage-3 underwent ovarian stimulation with letrozole (5mg/day) starting on cycle day 2 (CD2) and gonadotropins 150-450 IU on CD4 to cryopreserve embryos before chemotherapy. Oocyte maturation was triggered either with hCG (n = 89) or GnRHa (n = 54). Of these, 24 women underwent 31 frozen embryo transfers (ET). The mean age at cryopreservation was similar for ST and GC patients (35.6 ± 1.8 vs. 35.9 ± 1.0 years). The average time from completion of chemotherapy until ETs was similar (2.5 ± 1.2 vs. 2.3 ± 1.8 years). Overall clinical pregnancy per ET (CP/ET) and live birth per ET (LB/ET) rates were 71% (22/31) and 38.7% (12/31), respectively. Of the 31 ETs, 18 (58%) were with a GC. In comparing ST vs. GC groups, the CP/ET (10/13 vs. 12/18) and LB/ET rates (7/13 vs. 5/18) were not significantly different. Of the 24 women attempting pregnancy, 11 (46%) had at least one live birth. Of the 19 babies born (5 singletons and 7 set of twins) no birth defects were encountered. After the mean follow-up of 36.7 ± 11.0 months for those who conceived with ST, no cancer recurrences were encountered. A significant proportion of women attempting fertility preservation with letrozole-FSH was able to have at least one child without any adverse outcomes or recurrence. Regardless of whether FET was to self or GC, ovarian stimulation with letrozole-FSH continues to present a safe profile among women with breast cancer.