Background and aim: HER2 overexpression by immunohistochemistry is a prognostic maker in gastric cancer and helps to select candidates benefitted from targeted therapy with trastuzumab. This study is aimed at the assessing HER2 overexpression and its relationship with endoscopic and histopathological findings of gastric adenocarcinoma. Objectives and methods: Biopsy samples from 92 gastric cancer patients were examined for HER2 status by immunohistochemical staining. Results: 6.5% of tumors were cardia tumors and 93.5% were non-cardia tumors. Using the Lauren classification, 51.1% were intestinal type and 48.9% were diffuse type. Using WHO classification, 54.3% were tubular adenocarcinoma, 7.6% were mucinous adenocarcinoma, 15.2% were signet-ring cell carcinoma, and 22.8% were undifferentiated carcinoma. 32.6% were well-differentiated, 15.2% were moderately-differentiated, and 52.2% were poorly-differentiated carcinoma. HER2 was positive in 20.7% of gastric carcinomas, 50% cardia tumors and 18.6% non-cardia tumors. HER2 positivity among polypoid, fungating, ulcerated, and infiltrative types were 38.5%, 29.7%, 9.1% and 0%, respectively. HER2 overexpression in intestinal type was higher than that in diffuse type (31.9% vs. 8.9%, p = 0.009). HER2 overexpression in tubular adenocarcinoma, mucinous adenocarcinoma, signet-ring cell carcinoma, and undifferentiated carcinoma was 28.0%, 14.3%, 7.1% and 14.3%, respectively. HER2 overexpressions were different between differentiation degrees: 30% of well-differentiated tumors, 35.7% moderately-differentiated tumors, and 10.4% of poorly-differentiated tumors (p = 0.037). Conclusions: HER2 overexpression was found in 20.7% of endoscopic biopsy sample of gastric adenocarcinoma and was associated with endoscopic gross characteristic, Lauren histologic type and differentiation degree.
Extremely well-differentiated gastric adenocarcinoma arising in gastric adenomyoma
