P1.05-002 The Prognostic Impact of EGFR Mutation Status and Mutation Subtypes in Patients with Surgically Resected Lung Adenocarcinomas

Abstract

EGFR mutation status is a well-established predictor of the efficacy of EGFR tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer. Recently, the differences in EGFR mutation subtypes were also reported to be associated with the efficacy of EGFR TKIs. However, the prognostic impact of EGFR mutation status and mutation subtypes remains controversial. We retrospectively reviewed 945 consecutive patients with surgically resected adenocarcinomas who had their EGFR mutation status analyzed between January 2010 and December 2014. Overall survival (OS) and recurrence-free survival (RFS) were analyzed in three cohorts (all patients, pathological stage I patients, and patients with exon 21 L858R point mutation or exon 19 deletions) using Kaplan-Meier methods and Cox regression models. The median follow-up time was 42 months. The results for EGFR mutation status, mutation subtype, and the comparison data of OS/RFS are summarized in the attached Table. Positive EGFR mutation status was significantly associated with longer OS/RFS in all patients and was also associated with longer OS in pathological stage I patients. However, no significant differences were observed in OS/RFS between patients with exon 21 L858R point mutation and those with exon 19 deletions. In a Cox regression model for OS, the EGFR mutation status was a significant prognostic factor that was independent of well-established prognostic factors such as age, pathological stage, vascular invasion, lymphatic permeation, and serum CEA level.Tabled 13y-RFS5y-RFSP3y-OS5y-OSPAll Pts0.009< 0.001EGFR mut＋ (N = 423)84.6%76.7%95.2%89.0%EGFR mut- (N = 522)78.8%71.2%84.9%76.5%p stage I Pts0.102< 0.001EGFR mut＋ (N = 352)93.4%85.4%98.2%94.5%EGFR mut- (N = 392)90.6%82.8%92.6%85.9%Subtypes0.3850.507Ex 21 L858R (N = 224)84.8%79.6%95.2%90.0%Ex 19 del (N = 164)84.7%74.3%97.5%95.8% Open table in a new tab Positive EGFR mutation status is a favorable prognostic factor in patients with surgically resected lung adenocarcinomas. However, EGFR mutation subtypes (exon 21 L858R point mutation or exon 19 deletions) have no prognostic impact.