Immunohistochemical expression of HER2 in adenocarcinoma of the stomach

Worldwide, gastric cancer is the fourth cancer in incidence and the second most common cause of cancer death. Gastric cancer is asymptomatic in the early stages and very often diagnosed at advanced stages, determining a dismal prognosis. Expression of the HER2 gene has been identified in about 20% of gastric cancer cases, and its hyper-expression is associated with poor prognosis.

To investigate HER2 immunohistochemical expression in gastric adenocarcinoma and its relationship to the histological type and anatomic location.

A cross-sectional retrospective study analyzed the immunohistochemical expression of HER2 in a sample of 48 specimens of gastric cancer. Immunohistochemical analysis were performed using avidin-biotin-peroxidase method with C-erb B2 (clone EP1045Y), as a primary antibody (Biocare Medical, USA). Standardized gastric adenocarcinoma's HER2 expression criteria has been used in the analysis of samples.

There were seven cases with reactivity for HER2. Five were of intestinal-type while two cases were of mixed-type in which the expression occurred in the intestinal component. It was identified a significant association of HER2 expression in the intestinal subtype of gastric adenocarcinoma (P=0.003). Regarding the anatomical site, HER2 was positive in only one (16.6%) of the six proximal cases and six (14.28%) of the 42 distal cases (P=0.88).

HER2 immunoexpression was identified in 14.6% of the samples, and the expression was significantly associated to Lauren's intestinal subtype.