Immuno-Histochemical Assessment of HER2NEU Expression in Gastric Adenocarcinoma in North Karnataka, India

BACKGROUND AND OBJECTIVES: Gastric cancer is the fourth most common cancer worldwide and ranks fifth in India. Surgical resection is curative in early stage gastric cancers. Most of the gastric cancers are diagnosed at an advanced stage necessitating multimodality treatment strategies. Based on the ToGA trial, the international regulatory agencies have recently approved trastuzumab in locally advanced and metastatic gastric and gastroesophageal adenocarcinomas expressing HER2. Since there are limited studies from India and no published data available from this part of North Karnataka, we undertook this study to evaluate the frequency of expression of HER2 in gastric and gastroesophageal adenocarcinomas and to correlate it with various clinicopathological variables. METHODOLOGY: The study was conducted in the Department of Pathology, SDM College of Medical Sciences and Hospital, Dharwad, Karnataka from May 2012 to January 2016. The samples included both endoscopic biopsies and gastrectomies. Histopathological slides from 70 cases were reviewed. Immunohistochemical staining for HER2 was performed in all the cases and Hoffman’s gastric cancer scoring system was employed. The results of HER2 expression was correlated with various clinicopathological parameters. RESULTS: HER2 positivity was seen in 16/70 cases (23%). 6 cases (8.5%) were equivocal and 48/70 cases (68.5%) were HER2 negative. HER2 positivity was more common in GEJ cancers and intestinal type of adenocarcinoma. However, it did not correlate with age, gender, grade and stage. CONCLUSION: HER2 positivity was noted in 23% of the cases. 23.4% of intestinal type and 21.7% of diffuse type were HER2 positive. HER2 positivity did not significantly depend on age, gender, tumour type, grade and stage. Hence, HER2 remains as an independent biomarker and should be tested in all patients of gastric cancer regardless of the clinicopathological findings for offering a personalized treatment.