This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Breast, Subject name: Surgery
[{'content': 'Adjuvant therapy after mastectomy is needed in all of the following except: \nSelect and explain. \nA. High risk, node positive, B. Low risk, no node, C. ER/PR -ve, D. Her-2-neu +ve', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Criteria for adjuvant chemotherapy: (adverse prognostic factors) High histological grade Lymphovascular invasion Lymph nodes positive ER / PR negative Her - 2 - neu positive.', 'role': 'assistant'}]