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 carcinomas most frequently metastasizes to brain \nSelect and explain. \nA. Small cell carcinoma of lung, B. Prostate cancer, C. Rectal carcinoma, D. Endometrial cancer', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e. small cell Ca of lung Because of its high blood flow brain is a common site for metastasis. Primary sites in decreasing order are : Lung > breast > melanoma > kidney Prostate Ca, ovarian cancer and Hodgkin's disease rarely metastasizes to brain. (Ref: Harrison I7/e)", 'role': 'assistant'}]