Detection and Significance of Human Epidermal Growth Factor Receptor 2 Expression in Gastric Adenocarcinoma

Human epidermal growth factor receptor 2 (HER2) is involved in the pathogenesis of several types of cancer, including gastric cancer. Overexpression of HER2 is noted in 10%-22.8% of gastric adenocarcinoma and its identification is of immense importance for management by targeted drugs. Detection of HER2 expression in gastric malignancies has not been undertaken previously in the local population.

To ascertain HER2 immunohistochemical expression in gastric adenocarcinoma and its relationship with the anatomic location and histomorphology.

A total of 47 cases of gastric adenocarcinoma diagnosed over 2 years constituted the study group. Clinical history, type of operation, gross morphology, and hematoxylin and eosin (H and E) stained sections were reviewed. Two paraffin blocks were selected, immunostain was performed using rabbit monoclonal HER2 antibody and Hoffmann scoring system was applied.

Most of gastric carcinomas occurred in male (42 cases), having a mean age of 53.6 years. A total of eight cases (17.1%) had expressed a score of 3+ HER2 positivity. All positivity was noted in intestinal type according to Lauren classification (25%) and none in diffuse type. All HER2 score of 3+ was noted in histological grade of well and moderately differentiated adenocarcinoma. Score 2+ was noted in seven cases, among them, only two were poorly differentiated gastric adenocarcinoma.

HER2 overexpression was noticeably associated with an intestinal subtype, and well and moderately differentiated adenocarcinomas. Such cases of gastric adenocarcinoma are considered for targeted therapy with trastuzumab in the local population.