# Does the Immunohistotype of Breast Cancer Influence Ovarian Reserve and Fertility Preservation Outcomes? A Single-Center Prospective Observational Study

## TL;DR

This study found no significant differences in ovarian reserve or fertility outcomes between different breast cancer types before treatment.

## Contribution

The study provides new evidence that tumor immunohistotype does not compromise baseline fertility potential in breast cancer patients.

## Key findings

- No significant differences in ovarian reserve indices were found between triple-negative and hormone receptor-positive breast cancer patients.
- Luminal-B tumors showed a significantly lower mature oocyte yield in sub-analysis.
- Fertility preservation outcomes were not influenced by tumor immunohistotype at diagnosis.

## Abstract

Previous studies have hypothesized that patients with a more unfavorable oncological prognosis may present with a diminished ovarian reserve, potentially leading to poorer reproductive outcomes even prior to the initiation of gonadotoxic therapies. In the present prospective study involving 152 patients, we examined the relationship between the immunohistochemical profile of breast tumors (hormone receptors, HER2 receptor, and proliferative markers), ovarian reserve indices (AMH, antral follicular count), and the response to fertility preservation procedures (number of mature oocytes retrieved). Our analysis did not show significant differences between patients with triple-negative breast cancer and those with hormone receptor-positive disease.

Background: Breast cancer (BC) in reproductive-age women raises concerns about fertility preservation, particularly as systemic therapies may compromise ovarian function. Evidence on whether tumor immunohistotype influences ovarian reserve and fertility preservation outcomes remains limited. Methods: We conducted a prospective cohort study of BC patients referred for fertility preservation counseling between November 2020 and May 2025. Ovarian reserve was assessed using anti-Müllerian hormone (AMH) levels and antral follicle count (AFC). Controlled ovarian stimulation (COS) and oocyte cryopreservation were performed according to standardized protocols. Patients were stratified into triple-negative BC (TNBC) and hormone receptor-positive (HR+) and/or HER2+ groups. The primary endpoint was ovarian reserve differences by subtype; the secondary endpoints were ovarian response and oocyte yield. Results: Of 358 patients, 152 were enrolled, and 139 (91.4%) underwent COS, for a total of 145 cycles. The median age was 33 years, median AMH 5.4 ng/mL, and median AFC 17. No significant differences were observed between the TNBC and HR+/HER2+ groups in AMH, AFC, oocyte yield, or mature oocyte rate. Sub-analysis revealed a significantly lower mature oocyte yield in luminal-B tumors. Conclusions: Ovarian reserve and cryopreservation outcomes appeared preserved in TNBC compared with those in patients with HR+/HER2+ BC at diagnosis. These findings provide reassurance that baseline fertility potential is not compromised by tumor immunohistotype.