ALK and lung adenocarcinoma: EGFR mutations and ALK rearrangements have been recognized as driver genes, and several small molecule agents have been developed to attack these targets, leading to significant clinical improvements in these patient populations.25, 26, 27, 28 Demographic and subgroup analyses showed that mutations in these genes were more common in lung adenocarcinoma and less common in squamous cell carcinoma.29, 30, 31 The therapeutic options and alternative agents for squamous cell carcinoma are reduced compared to adenocarcinoma.