Should a woman age 70 to 80 years receive radiation after breast-conserving surgery?

Case 1: A 72-year-old woman presents with a palpable mass detected during yearly physical examination by her primary care physician. She has controlled hypertension and remains active, playing tennis three times a week. Physical examination reveals a 1.5 cm mass in the upper outer quadrant of the left breast with no palpable axillary lymphadenopathy. Diagnostic imaging reveals a suspicious mass, and core biopsy confirms invasive ductal carcinoma (IDC) that is estrogen receptor moderately positive (60%), progesterone receptor negative and Her2-neu that is not overexpressed. She undergoes a wide local excision and sentinel node biopsy. Pathology reveals a 1.5 cm IDC that is high grade without lymphovascular invasion (LVI). The margins are negative with the closest laterally at 2 mm. One sentinel node is negative for metastasis. Case 2: A 72-year-old woman presents with an abnormal screening mammogram that shows a small area of architectural distortion in the upper outer quadrant of the left breast (Fig 1). She is a former smoker with mild chronic obstructive pulmonary disease and has mild to moderately symptomatic osteoarthritis managed with a nonsteroidal anti-inflammatory agent. She remains active and independent. Physical examination reveals neither palpable breast mass nor axillary lymphadenopathy. Diagnostic ultrasound confirms a 1.8 cm mass, and core biopsy reveals IDC that is estrogen and progesterone receptor strongly positive (> 90%) and Her2-neu that is not overexpressed. She undergoes a wide local excision and sentinel node biopsy. Pathology reveals a 1.9 cm IDC that is low grade. The margins are widely negative at > 5 mm and there is no LVI. One sentinel node is negative for metastasis.