High impact of chemotherapy on ovarian reserve in breast cancer survivors of reproductive age: A systematic review and meta-analysis.

Introduction
The risk of infertility following breast cancer (BC) treatment is critical for women of reproductive age. Accurate risk assessment is essential for fertility counseling and preservation. Amenorrhoea as an infertility marker is unreliable due to endocrine therapies. Anti-Mullerian hormone (AMH) is a reliable fertility marker, but its role in assessing chemotherapy-induced loss of ovarian reserve in BC survivors remains underexplored.
Objective
This systematic review and meta-analysis evaluates AMH decline and the prevalence of low (AMH <1 ng/mL) and very low (<0.5 ng/mL) ovarian reserve in BC survivors <40 years old, 12-24 months post-chemotherapy, to quantify the gonadotoxic impact of BC treatments.
Methods
A systematic literature search of PubMed, Embase, and the Cochrane Library identified studies with AMH levels before and 12-24 months after chemotherapy in BC patients <40 years of age. Data on AMH levels were pooled using random-effects meta-analysis. Study quality was assessed using the Joanna Briggs Institute Critical Appraisal Checklist. This study is part of the FertiTOX project (www.fertitox.com).
Results
Ten studies (860 BC survivors) were included. Mean AMH decline was -1.61 (95 % CI: -2.31; -0.91) post-chemotherapy. The pooled prevalence of AMH <1 ng/mL and <0.5 ng/mL was 58 % (46-70 %) and 53 % (41-64 %), respectively. High heterogeneity was observed (I2 >80 %).
Conclusions
More than half of BC survivors have severely reduced ovarian reserve after chemotherapy, which is associated with a shortened fertile window and an increased risk of premature ovarian insufficiency. These findings highlight the need for pre-treatment fertility counseling and post-treatment ovarian insufficiency surveillance in routine oncology care.