There were 85 patients who were diagnosed as advanced lung adenocarcinoma with epidermal growth factor receptor (EGFR) 19 or 21 exon mutation in thoracic surgery of Xuanwu Hospital from February 2013 to November 2014, all of who were received EGFR-TKI as first-line treatment in the study. The gene discussed is EGFR; the disease is lung adenocarcinoma.