EGFR and non-small cell lung carcinoma: Patients with metastatic NSCLC which harbored activating EGFR mutations (exon 19 deletions and exon 21 L858R mutation) respond very well to first generation TKI (gefitinib and erlotinib) and second generation TKI (afatinib) as first-line treatment, as exemplified by international phase III RCT8–19.