Impact of Oncological Characteristics on Ovarian Reserve and Outcomes of the First Controlled Ovarian Stimulation Cycle in Patients with Breast Cancer

Abstract Objective To evaluate the effects of histological grade, tumor stage, estrogen receptor (ER) status, triple-negative breast cancer (TNBC) status, and Ki-67 expression level on baseline ovarian reserve and the outcomes of the first controlled ovarian stimulation (COS) cycle in breast cancer patients undergoing fertility preservation, and to identify factors associated with an optimal COS outcome. Methods This single-center retrospective cohort study analyzed the clinical data of 67 patients with breast cancer who underwent fertility preservation at the Reproductive Medicine Center of the Third Affiliated Hospital of Zhengzhou University between January 2020 and June 2026. Patients were grouped according to histological grade (grade I vs. grades II–III), tumor stage (stage I vs. stages II–III), ER status (ER-positive vs. ER-negative), TNBC status (TNBC vs. non-TNBC), and Ki-67 expression (< 30% vs. ≥30%). An optimal COS outcome was defined as retrieval of at least 8 mature (MII) oocytes. Intergroup comparisons were performed using the Student's t-test, the Mann–Whitney U test, the chi-square test, and Fisher's exact test. Binary logistic regression was used to identify factors associated with an optimal COS outcome. Results Sixty-one patients were ultimately included in the analysis. The mean age was 31.51 ± 4.64 years and the mean bilateral antral follicle count (AFC) was 18.08 ± 6.10. The median body mass index (BMI) was 21.80 kg/m² (interquartile range [IQR], 20.31–23.49) and the median anti-Müllerian hormone (AMH) level was 23.70 pmol/L (IQR, 14.61–33.84). No significant differences in baseline ovarian reserve parameters or in the outcome measures of the first COS cycle were found among the oncological subgroups (all P > 0.05). AMH and bilateral AFC were significantly higher in patients with ≥ 8 mature oocytes than in those with < 8 mature oocytes (both P < 0.05). Logistic regression showed that AMH (odds ratio [OR] = 1.125, 95% confidence interval [CI] 1.046–1.210) and bilateral AFC (OR = 1.235, 95% CI 1.090–1.400) were associated with retrieval of ≥ 8 mature oocytes. With follow-up through June 2026, six patients achieved pregnancy after completion of cancer treatment, including four live births; no abnormalities in neonatal physical development were observed. The clinical pregnancy rate and live birth rate per embryo transfer cycle were 33.33% (6/18) and 22.22% (4/18), respectively. Conclusions In this cohort, histological grade, tumor stage, ER status, TNBC status, and Ki-67 expression level did not significantly affect ovarian reserve or the outcomes of the first COS cycle in breast cancer patients. AMH and AFC were positively associated with the number of mature oocytes obtained.