Background: The presence of epidermal growth factor receptor (EGFR) mutations is an established prognostic factor for patients with advanced lung adenocarcinoma. Here, we examined whether EGFR mutation status is a prognostic factor for patients who had undergone surgery. Methods: Clinicopathologic data from 1,463 patients who underwent complete surgical resection for lung adenocarcinoma between 2005 and 2012 were collected. Differences in postoperative recurrence-free survival and overall survival according to EGFR mutation status were evaluated. Results: Of 835 eligible patients, the numbers of patients with wild-type EGFR (WT), exon 19 deletion (Ex19), and exon 21 L858R (Ex21) were 426, 175, and 234, respectively. Patients with Ex19 had a significantly higher incidence of extrathoracic recurrence than patients with Ex21 (p = 0.004). The 5-year recurrence-free survival rates for patients with WT, Ex19, and Ex21 were 63.0%, 67.5%, and 78.2%, respectively. The Ex21 group had a significantly longer recurrence-free survival than the WT group (p < 0.001) and the Ex19 group (p = 0.016). The 5-year overall survival for patients with WT, Ex19, and Ex21 were 76.9%, 86.5%, and 87.5%, respectively. Patients with Ex19 and Ex21 had a significantly longer overall survival than patients with WT (Ex19, p = 0.009; Ex21, p < 0.001). Multivariate analysis for recurrence-free survival showed that Ex19 was significantly associated with a worse prognosis than Ex21 (p = 0.019). Conclusions: Patients with Ex19 had significantly shorter recurrence-free survival and had extrathoracic recurrence more frequently than patients with Ex21 among patients with resected lung adenocarcinoma, implying that Ex19 could be a worse prognostic factor.
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