MET amplification occurrence and prediction of unfavorable clinical outcomes in patients with recurrent/metastatic gastric cancer after chemotherapy.

Abstract

e15047 Background: Several large studies have reported an extremely low incidence of MET gene amplification (GA) in patients with radically resected gastric cancer. The aim of our study was to evaluate the prevalence and prognostic role of MET GA and protein expression in recurrent/metastatic gastric cancer patients who received chemotherapy. Methods: This retrospective study included 232 recurrent/metastatic gastric cancer patients. MET GA and protein expression were evaluated by fluorescent in-situ hybridization (FISH) and immunohistochemistry (IHC), respectively.Results: MET GA and strong protein expression were observed in 8.3% and 9.6% of patients, respectively. MET IHC 3+ was significantly correlated with GA. Patients with MET GA more frequently had a poor performance status (P < 0.001) and poorly differentiate tumors (P = 0.015) than those without MET GA. Both MET GA and IHC 3+ expression were associated with substantially shorter median progression free survival (PFS) and overall survival (OS). The median OS and PFS for patients with MET GA positive vs. MET GA negative were 5.7 vs. 15.5 months (P < 0.001) and 3.6 vs. 6.9 months (P < 0.001), respectively.The median OS and PFS for patients with MET IHC 3+ vs. IHC (0 to 2+) were 6.3 vs. 15.1 months (P < 0.001) and 3.6 vs. 7.0 months (P < 0.001), respectively. Conclusions: In recurrent/metastatic gastric cancer, MET amplification and strong protein expression are not rare and significantly associated with unfavorable clinical outcomes.