women age ≥ 70 years;

new histological diagnosis of invasive carcinoma of the breast, grade i or ii, estrogen and progesterone receptor (er and pr) positive, her2 negative on needle biopsy and limited to stage i (t1 n0 m0) on clinical and radiological assessment with mri of the breasts and axillary ultrasound;

candidate for breast conserving surgery;

signed study consent form completed prior to study entry.

breast cancer with disease within 5 mm from skin or chest wall;

previous or concomitant invasive malignancies treated within 5 years of study entry;

serious non-malignant disease (cardiovascular, pulmonary, systemic lupus or scleroderma), which would preclude to definitive radiation therapy;

psychiatric disorders, which would preclude from obtaining informed consent

geographic inaccessibility for follow-up