Response to ovarian stimulation is not impacted by a breast cancer diagnosis

Study question: Does a breast cancer diagnosis impact ovarian function in the setting of fertility preservation?

Summary answer: Ovarian reserve and ovarian stimulation outcomes are similar in patients with a new diagnosis of breast cancer and patients undergoing elective fertility preservation.

What is known already: Prior studies, with small study populations, lack of controlling for individual differences in ovarian reserve and infertile controls, have reported conflicting outcomes for cancer patients undergoing ovarian stimulation for fertility preservation.

Study design, size, duration: This retrospective cohort analysis included 589 patients undergoing ovarian stimulation for fertility preservation between 2009 and 2015.

Participants/materials, setting, methods: Women with a recent breast cancer diagnosis (n = 191) and women desiring elective fertility preservation (n = 398) underwent ovarian stimulation with an antagonist protocol at an academic medical center. The aromatase inhibitor letrozole was administered to breast cancer patients with estrogen-sensitive disease.

Main results and the role of chance: Baseline antral follicle count (AFC) was not different between the breast cancer patients and controls (15.4 ± 10.4 [mean ± SD] vs 15.4 ± 10.0, P = NS), even after categorization by age. Total (19.4 ± 0.9 [mean ± SEM] vs 17.0 ± 0.5, P = NS) and mature (MII) oocytes retrieved (13.7 ± 0.7 vs 13.2 ± 0.4, P = NS), adjusted for age, BMI and total gonadotropin dose, were also similar between the two groups. Letrozole use was associated with a decreased maturity rate (MII/total oocytes retrieved) compared to elective cryopreservation (0.71 ± 0.01 vs 0.77 ± 0.01, P < 0.001), although the mature oocyte yield [MII/AFC] was comparable (1.01 ± 0.06 vs 0.93 ± 0.03, P = NS).

Limitations, reasons for caution: The single center design may impact generalizability. Additionally, the lack of subsequent embryo and pregnancy data is an inherent weakness.

Wider implications of the findings: In females, a breast cancer diagnosis does not impact gonadal function as measured by AFC or ovarian stimulation outcomes. Breast cancer patients should be counseled that their response to ovarian stimulation for fertility preservation is similar to that of patients undergoing elective oocyte cryopreservation.

Study funding/competing interest(s): None.

Trial registration number: N/A.