Gefitinib was approved for use in patients with locally advanced or metastatic NSCLC with activating mutations of EGFR-TK in July 2009, whereas erlotinib was approved as a first-line monotherapy in the same group of patients in September 2011, 2 years after the start of REASON [16, 17]. Here, EGFR is linked to non-small cell lung carcinoma.