OUTLINE: This is a randomized study. Patients are stratified by clinician. All patients are randomized following primary therapy, which, in addition to surgery, may include local irradiation, perioperative cyclophosphamide, or up to 6 cycles of cyclophosphamide, methotrexate, and fluorouracil (CMF) for high-risk patients. Clinicians may elect to randomize patients to all groups or to only those groups including tamoxifen. The first group receives no further therapy. Then second group receives tamoxifen daily for at least 2 years. The third group receives ovarian ablation with goserelin via monthly injection for at least 2 years. The final group receives ovarian ablation with goserelin plus daily tamoxifen for at least 2 years. All patients are followed every 3 months for 2 years, every 6 months for 3 years, then annually.