HER2 status in Gastric and Gastroesophageal Junction Adenocarcinoma

Gastric carcinoma is a biologically heterogenous disease and survival varies among the patients with same stage. Recent studies have shown that a subset of gastric and gastroesophageal junction adenocarcinoma over express the HER2/neu protein and these patients can be treated by monoclonal antibody against HER2/neu protein. The purpose of this study was to detect the frequency of HER2 expression in gastric and gastroesophageal junction adenocarcinoma and to evaluate the relationship between HER2 expression and clinicopathological features in these patients. This descriptive cross sectional study was carried out at the Department of Pathology, Dhaka Medical College, from January 2013 to December 2014. A total of 130 patients with primary gastric and gastroesophageal junction adenocarcinomas were included in this study. All the cases were evaluated for routine histological examination and immunohistochemical examination was done for HER2/neu protein. Among the 130 cases, HER2 over expression was found in 12.3% cases and was more frequent in gastroesophageal junction (28%) than in gastric carcinoma (8.6%) (P=0.026). HER2 positivity was found significantly more in intestinal type carcinoma (19%), papillary carcinoma (63%) and in fungating growth pattern (P=0.003, 0.001 and 0.001 respectively). HER2 expression was also positive in grade-I or grade-II tumor but negative in grade-III tumor (P=0.001). No significant association of HER2 expression was found with age, sex, lymph node metastasis and extent of tumor. In conclusion it can be stated that gastric and gastroesophageal junction adenocarcinoma of intestinal type or papillary and tubular type with well to moderate differentiation can be targeted for therapy using Herceptin.