This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Lung Tumors, Subject name: Pathology
[{'content': 'Which of the following histological type lung carcinoma has worst prognosis - \nSelect and explain. \nA. Squamous cell CA, B. Adenocarcinoma, C. Alveolar-carcinoma, D. Small cell carcinoma', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Small cell CA o Small cell carcinomas are the most aggresive of lung tumors, metastatize widely and are virually incurable by surgical means.", 'role': 'assistant'}]