Clinical significance of epidermal growth factor receptor mutations in resected stage IA non-small cell lung cancer

Background: Epidermal growth factor receptor (EGFR) gene mutation is a known predictor of the response to EGFR tyrosine kinase inhibitors. However, detecting EGFR mutations is a potential challenge because of the ground-glass opacity component, and its prognostic value for stage IA lung adenocarcinoma remains controversial. This study aimed to investigate the associations between EGFR mutation status, clinicopathological characteristics, and prognosis in surgically resected stage IA non-small cell lung cancer (NSCLC). Materials and Methods: We retrospectively examined the data of patients who underwent surgical resection for lung cancer between 2004 and 2014. The clinical data, imaging characteristics of nodules, surgical approaches, and outcomes were analyzed. Results: A total of 429 patients (female, n = 303; male, n = 126) with surgically resected stage IA NSCLC were analyzed and 343 were nonsmokers. The EGFR mutation rate was 48.3% (n = 207). Of the patients, 192 (44.8%) had stage IA1, 165 (38.5%) had stage IA2, and 72 (16.8%) had stage IA3 NSCLC. In the analysis of the correlations between clinicopathological features and EGFR status, older age (P = 0.032), nonsmoking history (P = 0.039), and pathological stage (P < 0.05) were related to EGFR mutation. Patients with stage IA2 NSCLC had a higher positive expression of EGFR than patients with stages IA1 and IA3. The 5-year overall survival rates and disease-free survival rates were better in the EGFR mutation group; however, the difference was not statistically significant. Conclusion: EGFR mutations are common in older and nonsmoking patients with stage IA NSCLC. Further separate analyses of EGFR gene mutations and pathological stage could improve the diagnostic performance and predict patients with unavailable EGFR gene testing who may benefit from targeted drug treatment.