EGFR and lung cancer: Brain metastases occur in approximately 30% to 40% of patients with non–small cell lung cancer (NSCLC) during the course of the disease and 20% to 25% of patients with advanced NSCLC have brain metastasis at the initial diagnosis.1 Patients with epidermal growth factor receptor (EGFR)-mutant NSCLC were more prone to the development of brain metastases, with an approximate frequency of 44% to 63% during the treatment course,2,3,4 which is higher than in patients with EGFR wild-type.