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 Here, EGFR is linked to lung cancer.