Immunohistochemical testing of HER2/neu protein overexpression in gastric cancer specimens and its clinicopathological correlation

Introduction: Gastric cancer is the 2nd leading cause of cancer mortality worldwide. It has shown to overexpress HER2 and is targetable with trastuzumab. Human epidermal growth factor receptor 2(HER2) is involved in the pathogenesis and poor outcomes of several cancers, including advanced gastric and gastroesophageal junction cancer. According to 2010 large multicentric ToGA study, Trastuzumab based therapy confers overall survival benefit in HER2 positive advanced gastric cancer patients. Hence determining HER2/neu overexpression by immunohistochemistry becomes highly pivotal in identifying the patients who are likely to respond to targeted monoclonal therapy. Aim and Objectives: Immunohistochemical evaluation of HER2/neu overexpression in gastric carcinomas and its correlation with various clinicopathological parameters. Materials and Methods: This is a retrospective and prospective study carried out at the Pathology Department of Dr. D.Y.Patil Medical College, Hospital and Research Center, Pimpri, Pune, over a period of 5 years (2012-16). HER2/neu immunohistochemistry (IHC) was performed on all the tumor sections and its overexpression was analysed. Results: HER2 immunohistochemistry was performed on 50 gastric adenocarcinoma cases, of which 21 cases (42%) showed overexpression. Intestinal subtype showed higher expression rates (48%) compared to diffuse subtype (33%) of gastric cancer and well-differentiated tumors showed highest HER2 [removed]60%). Conclusion: HER2 overexpression was present in 42% of gastric adenocarcinomas. However, there was no statistical significance between HER2 overexpression and its relation to clinicopathological parameters. It is necessary to conduct further studies with larger samples in order to draw definite conclusions regarding the role of HER2/neu overexpression as an independent prognostic factor. Keywords: Gastric adenocarcinoma, HER2/neu overexpression, Clinicopathological correlation.