RecruitingRadiation therapyConformal Ablative Radiotherapy in Older Women (CARMEN) With Breast Cancer Undergoing Non-Operative ManagementThis phase II study evaluates SABR as non-operative treatment for women aged 65+ with ER-positive, HER2-negative breast cancer ≤5 cm and no lymph node involvement. Eligible patients, including those previously on endocrine therapy, receive 5 SABR treatments, followed by monitoring of quality of life and assessment of treatment-related toxicity.