Assisted reproductive technology in young BRCA carriers with a pregnancy after breast cancer: An international cohort study.

Introduction Very limited data exist on assisted reproductive technology (ART) use in BRCA1/2 carriers conceiving after breast cancer. This study aimed to investigate the safety of ART to achieve a pregnancy after breast cancer in BRCA1/2 carriers.Methods This is an international, hospital-based, retrospective cohort study including BRCA1/2 carriers with a pregnancy after prior breast cancer diagnosis at ≤ 40 years of age between 2000 and 2020. Outcomes were compared between young BRCA1/2 carriers who conceived using ART and those who conceived spontaneously.Results Among 543 BRCA1/2 carriers with a pregnancy after breast cancer, 436 conceived spontaneously and 107 using ART. Of 107 pregnancies achieved with ART, 45 (42.1 %) were obtained using oocytes/embryo cryopreserved at diagnosis, 33 (30.8 %) after controlled ovarian stimulation for in-vitro-fertilization/intracytoplasmic sperm injection or ovulation induction for intrauterine insemination or planned intercourse after anticancer treatments, 21 (19.6 %) after oocyte donation, while for 8 (7.5 %) patients type of ART was missing. Compared to patients in the no-ART group, those in the ART group were older at the time of conception, had more frequently hormone receptor-positive breast cancer and a longer median time from cancer diagnosis to conception. At a median follow-up of 5.2 years after conception, no apparent detrimental effect of ART on disease-free survival was observed (adjusted HR=0.72, 95 % CI 0.39-1.34).Conclusion In young BRCA1/2 carriers with a pregnancy after breast cancer, ART use did not appear to be associated with increased risk of DFS events.