EGFR mutations are observed in 10–20% of patients not of East Asian descent with NSCLC and in approximately 40% of Asian patients.73 EGFR gene mutations mostly occur in adenocarcinomas, younger women and girls, and never-smokers,73,74 and are rarely identified in cases of lung cancer in smokers, which are usually more malignant than cases of lung cancer in nonsmokers.75 This evidence concerns the gene EGFR and adenocarcinoma.