Single Dose Ablative Radiation Treatment for Early-Stage Breast Cancer

Inclusion Criteria: * WHO performance scale ≤2. * Females at least 50 years of age with unifocal cT1N0 breast cancer or females at least 70 years of age with an unifocal cT1-2(maximum 3 cm)N0 breast cancer: \- Tumor size as assessed on MRI * On tumor biopsy: * Non-lobular invasive histological type carcinoma. * LCIS is accepted. * ER positive tumor receptor. * Tumor negative sentinel node. * Adequate communication and understanding skills of the Dutch language. Exclusion Criteria: * Legal incapacity * Indication for chemotherapy or immunotherapy (i.e. patients with an indication for endocrine therapy are eligible) * BRCA gene mutation. * Previous history of breast cancer * Other type of malignancy within 5 years before breast cancer diagnosis. For adequately treated carcinoma in situ of the cervix or basal cell carcinoma of the skin no specific time span from breast cancer diagnosis is required for inclusion * Her2neu positive tumor. * Previous history of ipsilateral breast surgery and impaired cosmetic outcome, as assessed by the treating surgeon or radiation-oncologist. * Collagen synthesis disease. * Signs of extensive DCIS component on histological biopsy or mammogram. * Invasive lobular carcinoma. * MRI absolute contraindications as defined by the Radiology Department. * Nodal involvement with cytological or histological confirmation. * Treatment with neo-adjuvant systemic therapy.