In recent years the role of ovarian ablation as a therapeutic modality not only in the prevention but also in the treatment of breast cancer has reemerged after its initial use more than a century ago. BRCA-1 and BRCA-2 mutation carriers have an 85% lifetime risk of developing breast cancer. Bilateral salpingo-oophorectomy is effective in reducing the risk of developing breast cancer in both BRCA-1 and BRCA-2 mutation carriers by 50%. Tamoxifen reduces the risk of breast cancer in BRCA-2 mutation carriers, but not in BRCA-1 mutation carriers. Breast cancer arising in BRCA-1 mutation carriers is often estrogen receptor (ER) negative, unlike breast cancer developing in BRCA-2 mutation carriers. Sixty percent of premenopausal patients with breast cancer have ER-positive disease and 25% of breast cancer patients are premenopausal at diagnosis. The Early Breast Cancer Trialists' Collaborative Group review has shown ovarian ablation to be an effective adjuvant therapy for premenopausal breast cancer patients less than 50 years of age. But the Early Breast Cancer Trialists' overview also shows the benefit of ovarian ablation is uncertain if these patients also receive chemotherapy. Does the overview underestimate the efficacy of ovarian ablation? Some patients in these trials were ER negative. Most women less than 50 years of age who receive adjuvant chemotherapy become menopausal. So there is a need to test ovarian function suppression in the group who can benefit, or in other words, those that remain premenopausal after chemotherapy and have endocrine responsive breast cancer.