Efficacy and safety of controlled ovarian hyperstimulation with or without letrozole for fertility preservation in breast cancer patients: A multicenter retrospective study.

Introduction: Fertility preservation (FP) is recommended in young breast cancer (BC) patients before (neo)adjuvant treatment. Letrozole-associated controlled ovarian hyperstimulation (LetCOH) is used worldwide to collect mature oocytes for FP, but its efficacy and safety compared to conventional protocols (cCOH) are still debated.

Aims: To compare efficacy and safety of FP procedure using LetCOH or cCOH in BC patients in terms of oocyte maturation rate and disease-free survival rates after at least two years of follow-up.