A PHASE III CLINICAL TRIAL EVALUATING DE-ESCALATION OF BREAST RADIATION FOR CONSERVATIVE TREATMENT OF STAGE I, HORMONE SENSITIVE, HER2-NEGATIVE,ONCOTYPE RECURRENCE SCORE d 18 BREAST CANCER

This study is being done to answer the following question: Is treatment with hormonal therapy as good as the usual treatment of radiation and hormonal therapy in women with low-risk breast cancer who have had lumpectomy? We are doing this study because we want to find out if this approach is better or worse than the usual approach for your breast cancer. The usual approach is defined as care most people get for low-risk, early stage breast cancer that is sensitive to hormones.