Non-smokers are most likely to develop which type of lung cancer?

• A. Adenocarcinoma
• B. Small cell carcinoma
• C. Squamous cell carcinoma
• D. Large cell carcinoma

Answer: (A)

In people who have never smoked, the most common type of lung cancer is adenocarcinoma. This histology tends to arise peripherally in the lung and is the cancer most often seen in never-smokers, as well as more common in women and in certain non-tobacco-related settings (such as exposure to radon or asbestos and specific genetic mutations like EGFR or ALK).

The other major lung cancers are more tightly linked to tobacco use. Squamous cell carcinoma and small cell carcinoma typically originate in the central airways and occur predominantly in smokers, reflecting the strong etiologic role of tobacco in those histologies. Large cell carcinoma is a less specific category and does not have as clear a link to smoking as the others.

So, when the patient has never smoked, adenocarcinoma fits best with the pattern of risk, geography within the lung, and epidemiology.