Clinicopathologic features and prognostic value of epidermal growth factor receptor mutation in patients with pT1a and pT1b invasive lung adenocarcinoma after surgical resection

Background: Previous studies have evaluated the prognostic value of epidermal growth factor receptor (EGFR) mutation in different subgroups of lung adenocarcinoma, but there remains controversial on this issue. We conduct this study aimed to reveal the prognostic value of EGFR mutation in patients with pT1a and pT1b invasive lung adenocarcinoma. Methods: From August 2009 to February 2015, 338 patients with pT1a and pT1b invasive lung adenocarcinoma who underwent EGFR mutation analysis were enrolled into this study. According to clinicopathologic and radiologic characteristics, survival analysis was conducted in different subgroups using Kaplan-Meier methods and Cox regression models. Results: EGFR mutation was detected in 216 (63.9%) patients. In the entire cohort, EGFR mutation was significantly frequent in female (P=0.011), never smoking (P=0.014) patients, patients with part-solid nodules (P=0.005) and patients with lepidic pattern-predominant adenocarcinoma (LPA)/acinar pattern-predominant adenocarcinoma (APA)/papillary pattern-predominant adenocarcinoma (PPA) (P=0.005). No difference in recurrence-free survival (RFS) was seen between patients harboring EGFR mutation and patients without EGFR mutation in the entire cohort (P=0.664) and the subgroup cohorts. Patients with EGFR mutation had a longer overall survival (OS) compared with patients without EGFR mutation in the entire cohort (P=0.005) and the subgroups of N0 stage cohort (P=0.013), N1-2 stage cohort (P=0.033), APA/PPA/invasive mucinous adenocarcinoma (IMA) cohort (P=0.011) and pT1b cohort (P=0.002). Tyrosine kinase inhibitors (TKIs) could significantly prolong the OS in patients with EGFR mutation after recurrence (P=0.04). Conclusions: EGFR mutation was not a risk factor for recurrence of patients with pT1a and pT1b invasive lung adenocarcinoma.