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': 'Which of the following is the most impoant prognostic factor in breast cancer? \nSelect and explain. \nA. Histological grade of the tumor, B. Stage of the tumor at the time of diagnosis, C. Status of estrogen and progesterone receptors, D. Over expression of p-53 tumour suppressor gene', 'role': 'user'}, {'content': "Answer: B \nExplanation: Components of tumor staging include major prognostic factors such as tumor size, invasion of the tumor, nodal involvement, distant metastases, inflammation and local features. Hence, stage of the tumor at the time of diagnosis is a better predictor of prognosis. Ref: Bailey and Love's Sho Practice of Surgery, 24th Edition, Page 839; Pathologic Basis of Disease By Robbins, 6th Edition, Page 1114.", 'role': 'assistant'}]