Multinational prospective trial of fertility preservation and assisted reproduction after interruption of adjuvant endocrine therapy in breast cancer patients

The multinational prospective POSITIVE trial evaluated intterruption of adjuvant endocrine therapy for early-stage hormone-receptor positive breast cancer in patients attempting pregnancy. After interruption, at least one pregnancy was reported by 74% of patients. Young age was the main factor associated with shorter time to pregnancy, with cumulative incidences of pregnancy by 1 year of 63.5%, 54,3%, and 37.7% for patients aged < 35, 35-39, and 40-42 years, respectively. Cryopreserved embryo transfer was the only assisted reproductive technology associated with higher chance of pregnancy (OR 2.41; 95% CI 1.75-4.95). The cumulative incidence of breast cancer-free interval events at 3 years was similar for women who underwent ovarian stimulation for cryopreservation at diagnosis (9.7%) compared with those who did not (8.7%). The authors conclude that in POSITIVE, fertility preservation using ovarian stimulation was not associated with short-term detrimental impact on cancer prognosis.