One possible reason for the response to erlotinib in EGFR-wt NSCLC is that erlotinib might target pathways related to antitumor activity other than the EGFR mutations because objective responses to erlotinib have been independently observed in EGFR-wt NSCLC patients, not only in those with adenocarcinoma but also in the squamous cell carcinoma subgroup, which usually has a low EGFR mutation rate [9], [33]. This evidence concerns the gene EGFR and adenocarcinoma.