The Role of Mutation Status of the Epidermal Growth Factor Receptor Gene In Advanced Non–Small Cell Lung Cancer

OBJECTIVE: The aim of this study was to examine the prevalence of epidermal growth factor receptor (EGFR) gene mutations among patients with advanced nonsquamous non-small cell lung cancer (NSCLC) treated in our institution and to evaluate the associations between EGFR mutations and clinicopathological characteristics. MATERIALS AND METHODS: A total of 103 patients with NSCLC were examined from April 2010 to September 2011. The patients were screened for EGFR mutations in exons 19 and 21 using sequence analysis. RESULTS: EGFR mutations were detected in 10 patients (9.71%): 23.1% of women and 5.2% of men (P<0.05), 31.8% of never-smokers and 4.7% of smokers (P<0.05), and 12.3% of patients with adenocarcinomas and 6.25% of patients with large cell carcinomas (P>0.05). Eight mutations (80.0%) were found in exon 21: 7 patients had the L858R mutation and 1 patient had the L861G mutation. Two mutations (20.0%) were found in exon 19: 1 patient had the L747-A748 deletion and 1 patient had the L747-A750insE deletion. The overall response rate was significantly greater in the EGFR mutation-positive group than in the EGFR mutation-negative or control groups (P<0.05). The median progression-free survival in the EGFR mutation-negative group and the control group that received systemic standard chemotherapy was 5.6 months (95% CI, 4.3 to 7.0) and 5.3 months (95% CI, 4.9 to 5.7), respectively, but it was not achieved in the EGFR mutation-positive group that received EGFR tyrosine kinase inhibitors (P<0.05). CONCLUSIONS: The frequency of EGFR mutations in our patients with nonsquamous NSCLC was found to be similar to that reported in Europe. EGFR mutations were more frequent in women and never-smokers.