Partial Breast Irradiation (PBI) Using 40 Gy for Select Patients With Early Invasive or Noninvasive Breast Cancer

A dose of 40 Gy will be delivered to the tumor bed plus 1.5-2 cm margin. Treatment will be delivered once daily, 5 days a week, for approximately 2 weeks. Radiation therapy will begin within a minimum of 4 weeks and a maximum of 3 months from definitive surgical procedure and 2-6 weeks after chemotherapy, if chemotherapy given first. Prior to radiation, patients will receive a lumpectomy with an assessment of axillary lymph node status (for invasive tumors only). Axillary assessment may be any combination of sentinel lymph node biopsy or axillary lymph node dissection.