At the time of this writing, phase II trials in which patients with advanced NSCLC are included on the basis of presence of the two most common EGFR mutations (either exon 19 deletions or the exon 21 arginine-for-leucine substitution at amino acid 858, or L858R) and are given gefitinib as first-line treatment show radiographic response rates that exceed 75% [9–11]. This evidence concerns the gene EGFR and non-small cell lung carcinoma.