Identification of HER2 protein overexpression and gene amplification in gastric cancer

Gastric cancer is a leading cause of cancer related mortality, and current treatment outcomes for advanced disease remain poor. HER2 protein overexpression and gene amplification are significant biomarkers for identifying gastric cancer patients who possibly respond to HER2-targeted therapy using trastuzumab.The aim of this study was to identify prevalence rate of HER2 gene amplification/overexpression in a local population, and determine the concordance rate between IHC and FISH techniques.Formalin-fixed, paraffin-embedded sections of 43 adenocarcinoma specimens from 61 cases of gastric cancer patients were analyzed. Protein expression was assessed using immunohistochemistry and gene amplification was evaluated by fluorescence in situ hybridization.11.7% (5/43) and 7,5% (3/40) of gastric adenocarcinomas displayed HER2 protein overexpression (score 3+/2+) and gene amplification, respectively. The concordance between IHC and FISH is high.