Background: This study aimed to evaluate mutations of the epidermal growth factor receptor (EGFR) and K-ras genes and their clinicopathological and prognostic features in patients with resected pathological stage I adenocarcinoma. Methods: We examined 224 patients with surgically resected lung adenocarcinoma and analyzed the prognostic and predictive value of these mutations in 162 patients with pathological stage I adenocarcinoma. Results: Mutations of the EGFR and K-ras genes were detected in 100 (44.6%) and 19 (8.5%) of all tumors, and in 81 (50.0%) and 17 (10.5%) of the pathological stage I tumors, respectively. EGFR mutations were significantly associated with female gender, smoking habit (never smoker), and low grade. By contrast, K-ras mutations were significantly associated with male gender, smoking habit (ever smoker), and the presence of mucinous components. No significant differences were observed in recurrence-free or overall survival between the EGFR-mutant, K-ras-mutant, and wild-type groups (five-year recurrence-free survival 77.8% vs. 87.8% vs. 79.5%; five-year overall survival 82.8% vs. 82.4% vs. 79.2%, respectively). Multivariate analysis showed that neither EGFR nor K-ras mutation was an independent prognostic factor. Conclusions: The present study demonstrated that pathological stage I adenocarcinoma harboring EGFR and K-ras gene mutations have distinct clinicopathological features. The presence of these mutations alone were not prognostic factors in patients with resected pathological stage I adenocarcinoma.
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