Survival significance of epidermal growth factor receptor tyrosine kinase inhibitors and current staging system for survival after recurrence in patients with completely resected lung adenocarcinoma

OBJECTIVE We previously reported that the staging system and epidermal growth factor receptor (EGFR) mutation status are key factors for treatment strategy and predicting survival. However, the significance of these factors as predictors of overall survival (OS) and postoperative recurrence survival (PRS) has not been sufficiently elucidated. The objective here was to investigate EGFR mutation status and p-stage, which affect PRS and OS in patients with completely resected lung adenocarcinoma, using a different database. PATIENTS AND METHODS We retrospectively reviewed 56 consecutive lung adenocarcinoma patients with disease recurrence in St. Marianna University Hospital between January 2010 and December 2014. RESULTS EGFR mutants (M) were detected in 16/56 patients (29%). The patients with EGFR M had a better OS than those with EGFR wild-type (WT) status (5-year survival: 50.3% vs 43.1, P=0.133). There was no significant difference in the 3-year recurrence-free survival rate between patients with M and WT (6.3% vs 7.7%, P=0.656), and the patients with EGFR M had a significantly better 3-year PRS than those with WT (77.4% vs 51.7%, P=0.033). The 3-year PRS rate for patients with M/pathologic stage (p-stage) I-II (87.5%) was better than that for patients with M/p-stage III (60.0%), WT/p-stage I-II (52.7%), and WT/p-stage III (43.8%). There was a significant difference between patients with M/p-stage I and WT/p-stage I-II or WT/p-stage III (P=0.021 and 0.030, respectively). During the study period, of the 16 patients with mutants, 12 patients (75%) received EGFR-tyrosine kinase inhibitor (TKI) therapy and among the 40 patients with WT, no patient received EGFR-TKI therapy. Multivariate survival analysis showed that patients with EGFR-TKI therapy had a statistically significant association with favorable PRS (hazard ratio 0.271; 95% confidence interval 0.074-1.000; P=0.050). CONCLUSION EGFR status and p-stage were found to be essential prognostic factors for estimating PRS using this database. The recurrent patients with EGFR M and EGFR-TKI therapy had a statistically significant association with favorable PRS.