Expression of HER2 in gastric cancer: Comparison between protein expression and gene amplification using a new commercial kit

Abstract

4053 Background: Trastuzumab, a monoclonal antibody to HER2 protein, is widely used in patients with HER2-overexpressing breast cancer. Trastuzumab has also shown antitumor activity in human gastric cancer (GC) xenograft models with HER2 overexpression, however, the concordance of protein expression and gene amplification of HER2 in GC cells and the feasibility of using biopsy specimens has not been clarified Aim: The purpose of this study was to evaluate the frequency of HER2 overexpression and the concordance between protein expression and gene amplification in surgical and endoscopic biopsy GC specimens using two commercial immunohistochemical(IHC) kits and fluorescence in situ hybridization (FISH). Materials and Methods: The specimens consisted of formalin-fixed, paraffin-embedded sections of biopsy specimens and surgically resected tumors in 200 cases with invasive GCs who underwent surgery at the National Cancer Center Hospital East. The IHC analysis was performed using the Hercep Test kit (DAKO Cor...