Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) such as gefitinib can provide better efficacy and prolonged progression free survival (PFS) than cytotoxic chemotherapy for metastatic lung non-squamous cell carcinoma harboring susceptible EGFR mutations when used as first-line therapy. | The salvage therapy in lung adenocarcinoma initially harbored susceptible EGFR mutation and acquired resistance occurred to the first-line gefitinib and second-line cytotoxic chemotherapy