Overexpression of Her2/Neu in Gastric Carcinoma: Association with Histological Type, Tumor Grade and H. Pylori Infection

Introduction: Gastric cancer is the second leading cause of cancer mortality in the world and its management, especially in advanced stages, has evolved relatively little. In particular, no targeted modality has so far been incorporated for treatment. HER2 over-expression is increasingly recognized as a frequent molecular abnormality, driven as in breast cancer by gene amplification. There is mounting evidence of the role of HER2 over-expression in patients with gastric cancer, and it has been strongly correlated to poorer outcomes and a more aggressive disease. Aims and objective: The purpose of this study is to establish the clinicoepidemiological, histopathological and immunohistochemical particularities of the gastric carcinomas, and to identify the factors with a prognostic value. Materials and methods: The present study included 54 cases of gastric carcinoma, who had undergone endoscopy guided biopsy or gastrectomy. Expression of HER2 oncoprotein by immunohistochemistry and detection of Helicobacter pylori was done using modified Giemsa stain. Expression of HER2 was correlated with patient’s clinicopathological parameters. Results: HER2+ rates were 22.22% (12/54). HER2 over-expression was associated with poorly differentiated carcinoma (P = 0.0159) and intestinal type of gastric carcinoma (P=0.0245). Original Article *Corresponding author: Dr. Indranil Chakrabarti, Department of Pathology, North Bengal Medical College Sushrutanagar, District: Darjeeling, West Bengal, India-734012 Phone: + 91 9433187448 Email: [email protected] A-184 HER2/neu and H.Pylori in Gastric Carcinomas Annals of Pathology and Laboratory Medicine, Vol. 03, No. 03, July September 2016 Introduction Gastric cancer is the fourth most commonly diagnosed malignancy and the second most common cause of cancer related death worldwide.[1,2,3]Although there has been great improvement in the early diagnosis of gastric cancer, in combination with the recent progress of surgical techniques and comprehensive use of chemotherapy and radiotherapy, the 5-year survival rate for gastric cancer remains as low as 20% to 30%.[4]In regard to gastric cancer, molecularly targeted therapy is also gaining status. There is mounting evidence of HER2 expression in gastric carcinoma correlating with poor outcomes and a more aggressive disease.[5]According to the ToGA clinical trial reported in 2010 [6,7], patients with HER2 overexpression receiving chemotherapy and trastuzumab had a significant longer median overall survival without any additional adverse side effects. So, targeted therapy has great potential in improving the treatment of gastric cancer. Helicobacter pylori (H. pylori), previously named Campylobacter pyloridis, is a Gramnegative, microaerophilic bacterium found in the stomach. It has been known that H. pylori have a major role in EGFR receptor expression in gastric mucosal cells. [8] Changes like growth, proliferation and differentiation are observed with EGF receptor expression. This overexpression may cause development of gastric cancer. There are studies, which have indicated that EGF and EGFR levels were decreased in cells with H. pylori eradication. [8] The limited number of studies in the literature has investigated HER2 status both in gastric and its metastatic tissues. However, after extensive search the relationship of this status with H. Pylori has been found only in one recent study in this year. So, this study will be helpful for assessment of prognostic significance of HER2 in gastric carcinoma along with the role of anti H. Pylori medication in Her2 positive cases. Aims and Objective: The present study was undertaken to evaluate the pattern and intensity of HER2/neu expression in different histomorphologic variants as well as grades of gastric carcinoma and to find out the frequency of H pylori infection in HER2/neu positive gastric carcinoma patients. Materials and Methods The study was carried out during the time period of one year from June 2011 to May, 2012 after obtaining the permission of Institutional Ethics Committee. A total of 54 histologically diagnosed cases of gastric carcinoma were included. All the relevant history was recorded. After conventional processing, paraffin sections of 5μm thickness were stained by haematoxylin and eosin (H and E) for histopathological study and modified Giemsa for detection of H.pylori. In addition, 4μm sections were cut from paraffin blocks of tumour tissue and taken on a glass slide coated with poly L lysine for immunohistochemistry (IHC) to detect HER2 overexpression. The technique for IHC included antigen retrieval in Tris-EDTA buffer by pressure cooker method, blocking endogenous peroxidase with 3% hydrogen peroxide, incubating with primary mouse monoclonal antibody against HER2 protein (CB11), linking with secondary antibody, enzyme labelling with streptavidin-horseradish peroxidase, developing chromogen with di-amino benzidine (DAB) and counterstaining with haematoxylin. Positive and negative controls were checked with each batch of slides. Statistical analysis was performed using Microsoft Excel and SPSS software version 11.5. The results were considered statistically significant if p <0.05. Results and Analysis After data accumulation they were analysed and the following results were obtained. A total number of 54 cases were included in the study and were morphologically classified as per Lauren classification of gastric carcinomas ( Figure 1) Regarding immunohistochemical staining for HER2/ neu following data were obtained: 30 cases out of 54 cases (55.56%) showed negative staining (score 0 and 1+). Intense complete staining (score 3+) were detected in 12 cases (22.22%). The remaining 12 cases (22.22%) showed moderate partial membranous staining (2+) in >10% cells. (Table -1) (Figure 2) Overexpression of HER2 oncoprotein was seen predominantly in patients over 50 years of age and male population.(Table -2&3) Most of the cases showing HER2 over expression were intestinal type (P= 0.0245) except two cases where diffuse type showed positivity. No other histological variant (mixed and indeterminate type) showed positivity.(Table-4) HER2 over expression was seen in 8 cases (P=0.0159) of high grade gastric carcinomas. (Table -5) Among the 12 cases which showed positive staining of HER2 oncoprotein, H. pylori was detected in 2 cases (P value= 1) using modified Giemsa stain. (Table -6) (Figure 1D) Discussion In this study out of 54 gastric carcinoma only 12 cases were HER2 positive and HER2 status was correlated with