Premature ovarian insufficiency (A) by trial, and (B) by patient subgroup. GBG-37 ZORO, German Breast Group-37 ZOladex Rescue of Ovarian function; GnRHa, gonadotropin-releasing hormone agonists; OPTION, Ovarian Protection Trial in Oestrogen Non-responsive Premenopausal Breast Cancer Patients Receiving Adjuvant or Neo-adjuvant Chemotherapy; OR, odds ratio; POEMS, Prevention Of Early Menopause Study; PROMISE-GIM6, PRevention Of Menopause Induced by chemotherapy: a Study in Early breast cancer patients—Gruppo Italiano Mammella 6; pts, patients.