Fertility Preservation Using Controlled Ovarian Stimulation in Breast Cancer: A Comparative Study of Neoadjuvant and Adjuvant Settings

Purpose: To compare the time to initiation of first oncologic treatment and the outcomes of controlled ovarian stimulation (COS) in breast cancer patients undergoing fertility preservation (FP) in the neoadjuvant chemotherapy (NAC) versus adjuvant chemotherapy (AC) treatment settings. Methods: A retrospective cohort study involving patients with stage 1-3 breast cancer treated with NAC/AC, who underwent FP with random-start COS, between 2015-2023. Baseline, oncologic and COS characteristics and outcomes were collected. Time points related to cancer diagnosis, FP, and first oncologic intervention (surgery or chemotherapy) were calculated. Results: 70 NAC-treated patients were compared to 42 AC-treated patients. Groups were similar in terms of age, marital status, parity and BMI. NAC-treated patients had more advanced disease, more often with lymph node involvement. Median time from diagnosis to FP consult (17 vs 30 days) and to stimulation start (22 vs 59 days) was significantly shorter for NAC-treated patients. Median time from diagnosis to first oncologic intervention was slightly longer for NAC-treated patients (45 vs 41 days, p<0.05). Stimulation characteristics were comparable apart from a less frequent use of hCG trigger among NAC-treated patients (4% vs 16%, p<0.05). First stimulation cycle outcomes such as peak E2 levels, number of retrieved oocytes and fertilization rate were similar, though median number of M2 oocytes was higher in NAC- treated patients (11 vs 8, p<0.05). Conclusion: Expedited patient care at the neoadjuvant setting led to a statistically significant, yet clinically minimal, delay of cancer therapy. Neither oncologic treatment timelines nor FP outcomes were compromised in the NAC setting.