Gefitinib is a specific and effective epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), and it has been studied and used to treat lung adenocarcinoma patients with activating EGFR mutations, such as exon 19 deletion and exon 21 L858R mutation [4, 5]. This evidence concerns the gene EGFR and lung adenocarcinoma.