In the last 5 years, evidence has accumulated that there are genetically-defined molecular subsets of lung adenocarcinoma, the most remarkable subset being patients with epidermal growth factor receptor (EGFR) gene mutations, which defines a small subset of patients with NSCLC who have high sensitivity to EGFR-tyrosine kinase inhibitors (TKIs) such as gefitinib and erlotinib [3, 4]. This evidence concerns the gene EGFR and lung adenocarcinoma.