Clinicopathological and prognostic features of surgically resected pathological stage I lung adenocarcinoma harboring epidermal growth factor receptor and K‐ras mutation

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.