EMERALD: Endocrine Therapy oMission With Radiation in ER+ Breast Cancer: Assessing Quality of Life and Disease Control: a Prospective Phase II Trial

Primary Objective: To determine the 3- year DMFS rate of radiotherapy as adjuvant monotherapy for early stage, low risk breast cancers in patients aged ≥ 60 years Secondary Objectives: 1. To determine the HRQoL of patients ≥ 60 years with early stage, low risk breast cancer receiving adjuvant monotherapy with radiotherapy 2. To determine the 3-year and 5-year risk of ipsilateral breast tumor recurrence (IBTR) for early-stage breast cancers treated with lumpectomy and adjuvant radiotherapy without endocrine therapy 3. To quantify the 3-year and 5-year rates of local-regional recurrence, contralateral breast cancer, breast cancer-specific survival and overall survival and the 5 year rate of DMFS 4. To determine the 5-year utilization of salvage mastectomy and other salvage therapies 5. To determine late (up to 11 year) oncologic outcome data for patients accessible via chart review or phone call 6. To determine the toxicities experienced by patients ≥ 60 years with early stage, low risk breast cancer receiving adjuvant monotherapy with radiotherapy