This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'The most important prognostic factor in carcinoma breast is \nSelect and explain. \nA. Size of tumour, B. Skin involvement, C. Axillary gland involvement, D. Involvement of muscles', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The\xa0Nottingham prognostic index\xa0(NPI) is used to determine prognosis following surgery for breast cancer.\xa0\nIts value is calculated using three pathological criteria:\xa0the size of the lesion; the number of involved lymph nodes; and the grade of a tumour.\nSize of the lesion is least important.\nThe extent of\xa0axillary lymph node involvement\xa0by breast cancer—is the\xa0most established and reliable prognostic factor for subsequent metastatic disease and survival', 'role': 'assistant'}]