RESULTS: One hundred and thirty four patients displayed EGFR mutations in exon 19 and exon 21 from October 2002 to December 2015. The mean age was 68.6 years and smoking rate was 26.5%. 88 patients (65.7%) had EGFR 19 deletion and 34.3 % (46 patients) in L858R mutation. The stages were III 18 patients, IVa 31 patients, and IVb 81 patients, respectively. The most patients (91.8 %) were adenocarcinoma, 6% patients were squamous cell carcinoma. Forty six patients treated with only EGFR-TKIs, 16 patients with only chemotherapy, and 72 patients with both therapies. In EGFR-TKI treatment, 67 patients in first line, 51 patients in second line or more were treated. Overall survival (OS) was longer in good performance status (p=0.003), non-smoker (p=0.085), WBC ≤ 10,000 m/L (p=0.001), CEA ≤ 10 ng/mL (p=0.031), NSE ≤ 20 ng/mL (p = 0.084), and EGRF-TKIs treatment (p=0.02). After treatment with gefitinib (n=75), erlotinib (n = 31), and afatinib (n=12), patients with EGFR mutations had a median OS of 22.3 ± 2.2 months and median progression free survival (PFS) was of 8.7 ± 0.7 months. PFS was longer in lower CEA level group (p=0.003). According to the type of drug there showed similar survival curves, but the PFS of afatinib treated patients was longer tendency than erlotinib (p=0.07). There were no clinical differences between 19 deletion and L858R groups in sex, age, smoking status, ECOG status, body surface area, stages, PFS, and OS, only except smoking amount in 19 deletion groups. The median PFS of the patients with lower CEA was longer than that of those with lower CEA (p = 0.019) in exon 19 mutation group. The PFS of afatinib and gefitinib was longer than erlotinib only in 19 deletion (p=0.041, 0.018, respectively).