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
Adjuvant therapy after mastectomy is needed in all of the following except: 
Select and explain. 
A. High risk, node positive, B. Low risk, no node, C. ER/PR -ve, D. Her-2-neu +ve
B: Low risk, no node
Answer: B: Low risk, no node 
Explanation: Criteria for adjuvant chemotherapy: (adverse prognostic factors) High histological grade Lymphovascular invasion Lymph nodes positive ER / PR negative Her - 2 - neu positive.