ALK and adenocarcinoma: Nevertheless, a growing body of literature suggests that NSCLC in never-smokers has several distinct clinical, pathological, and molecular characteristics implying that it might be a different disease compared with NSCLC in smokers (36); adenocarcinoma is the most frequent histology in never-smokers and alterations in driver oncogenes such as EGFR, and ALK are more common in tumors from never-smokers compared to smokers.