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: Pathology
Most common lung cancer in non-smokers is: September 2010 
Select and explain. 
A. Adenocarcinoma, B. Squamous cell carcinoma, C. Oat cell carcinoma, D. None of the above
A: Adenocarcinoma
Answer: A: Adenocarcinoma 
Explanation: Ans. A: Adenocarcinoma Adenocarcinoma accounts for 40% of non-small cell lung cancers. It usually originates in peripheral lung tissue. Most cases of adenocarcinoma are associated with smoking; however, among people who have never smoked ("never-smokers"), adenocarcinoma is the most common form of lung cancer. A subtype of adenocarcinoma, the bronchioloalveolar carcinoma, is more common in female never-smokers, and may have different responses to treatment.