Radiation Therapy for Early-Stage Breast Cancer after Breast-Conserving Surgery

A 45-year-old woman with a family history of postmenopausal breast cancer (in a maternal aunt) discovers a mass in the upper outer quadrant of her left breast. A mammogram reveals a spiculated density considered suspicious for cancer, and a core biopsy of the lesion reveals a high-grade infiltrating ductal carcinoma that is negative for estrogen and progesterone receptors and for HER2/neu. A lumpectomy and dissection of the sentinel lymph nodes are performed. Pathological evaluation reveals a 1.5-cm infiltrating ductal carcinoma with 3-mm disease-free surgical margins and two negative sentinel lymph nodes. After undergoing 6 months of adjuvant chemotherapy, the patient is referred to a radiation oncologist, who recommends irradiation of the left breast.