Does higher starting dose of FSH stimulation with letrozole improve fertility preservation outcomes in women with breast cancer?

Objective: To evaluate the efficacy of ovarian stimulation with higher doses of gonadotropins in fertility preservation (FP) cycles with the intention to maximize the likelihood of future pregnancies. Design: Retrospective (secondary analysis). Setting: Academic medical centers. Patient(s): Low-dose (LD, 150 IU; n = 34) versus high-dose (HD, >150 IU; n = 117) FSH start in 151 patients with breast cancer (BCa) undergoing ovarian stimulation for embryo cryopreservation with letrozole (LE) before cancer treatment. Intervention(s): None. Main Outcome Measure(s): FP cycle outcomes. Result(s): Mean total FSH dose (2,037 ± 679 IU vs. 1,128 ± 381 IU) and FSH level on trigger day (21.1 ± 8.9 vs. 10.6 ± 4.5 mIU/mL) were higher in the HD group, confirming the receipt of higher-dose FSH. There was no difference in other patient characteristics. Despite the larger number of follicles >17 mm in diameter in the HD group (5.0 ± 2.0 vs. 3.4 ± 1.4), neither peak E₂ (498.0 ± 377.5 vs. 397.9 ± 320.3), number of oocytes (13.3 ± 8.7 vs. 12.3 ± 8.0), nor number of embryos (6.3 ± 4.7 vs. 5.4 ± 3.8) were significantly different from the LD group. Of those undergoing frozen embryo transfer (ET), live birth rate (LBR)/ET trended higher in the LD (9/15) compared with HD (2/11) group, with 2.1 ± 0.8 vs. 1.9 ± 0.3 embryos transferred, respectively. Conclusion(s): Higher-dose FSH stimulation in LE cycles does not improve outcomes and may be associated with lower LBR. Our findings may support minimal stimulation in young noninfertile women with BCa.