HER 2 Expression in Gastric and Gastro-esophageal Junction (GEJ) Adenocarcinomas

Introduction: Gastric cancer is one of the leading causes of cancer mortality in the world/India with majority being diagnosed at an advanced stage. Various chemotherapeutic regimens have modestly improved overall survival leading to quest for novel therapeutic agents. Overexpression of HER2 in many gastric cancers has lead to the advent of targeted therapy with anti HER2 antibody like Trastusumab which has improved the overall survival. Materials and Methods: Sixty cases of gastric adenocarcinomas (44 biopsies and 16 gastrectomies) over the past five years ( June 2009 to June 2014),were included in the study. Diagnosis was confirmed by review of slides and IHC with anti HER2 antibodies was performed using Dako Real Envision Detection system and scoring was done by Hoffmann et al., scoring system. Results: Of the 60 cases, majority were males (60%),with a mean age of 65.65 yrs. Tumours in antrum (76.7%) formed the major bulk. HER2 expression was observed in 26.7% of Tumours, predominantly in males (p=0.006) and intestinal type (p= 0.054). HER2 expression correlated with Tumour grade (moderately differentiated and well differentiated, p= 0.042). Tumours of gastro-esophageal junction (GEJ) showed HER2 expression in 45.5% as opposed to 22.4% in gastric location. Poorly differentiated and diffuse type of adenocarcinomas did not express HER2. Two of three Tumours from patients in the age group 31-40 y expressed HER2. Conclusion: Male gender, intestinal-type and moderately differentiated gastric cancers may be the ones that can be targeted for therapy using Herceptin. Though trastusumab is approved for advanced gastric and GEJ cancers, its role in adjuvant / neo-adjuvant setting in early stages needs to be evaluated with newer agents like Pertuzumab, Bevacizumab, especially in young patients.