MET Gene Amplification and Overexpression in Chinese Non–Small-Cell Lung Cancer Patients Without EGFR Mutations

Abstract

BackgroundThe prevalence and clinical pathologic characteristics of MET amplification and overexpression in Chinese patients with non–small-cell lung cancer (NSCLC) remain unknown. In this multicenter study, we sought to reveal the frequency and clinical pathologic characteristics of MET amplification and to explore the predictive value of MET amplification and overexpression status in relation to survival in Chinese NSCLC patients. Patients and MethodsMET amplification was detected by fluorescence in-situ hybridization in 791 patients with EGFR wild-type samples. MET protein expression was detected by immunohistochemistry. ResultsIn total, 8 of 791 NSCLC patients with EGFR wild type patients were identified as harboring MET amplification. Among these 8 patients, 1 had adenosquamous carcinoma histology and 7 adenocarcinoma. There was no statistically significant difference among age, sex, smoking status, and histologic type between patients with and without MET amplification. MET amplification was more frequent in advanced-stage disease and in the solid predominant subtype of adenocarcinoma. MET protein expression was performed in 395 patients, and 138 were positive. Patients positive for MET protein expression had worse overall survival (OS) compared to those without MET protein expression (45.0 vs. 65.8 months; P = .001). Multivariate analysis revealed that MET expression was an independent prognostic factor for poor OS (R = 1.497, P = .017), while MET amplification had weak relevance for OS (hazard ratio = 1.974, P = .251). ConclusionMET amplification was rare in Chinese NSCLC patients without EGFR mutation, with a prevalence of about 1%. MET expression but not amplification could be an independent prognostic factor for shorter OS among these EGFR wild-type NSCLC patients.