Overexpression of cyclooxygenase-2 and tumor angiogenesis in human gastric cancer

Background/Aims: Cyclooxygenase-2 (COX-2) protein is overexpressed in various cancers, including esophageal, gastric, colon, and pancreatic. To better comprehend the role of COX-2 in gastric cancer, especially with regard to angiogenesis, we investigated COX-2 and vascular endothelial growth factor (VEGF) expression and microvessel density (MVD) in 108 patients with gastric cancer. Methodology: We used immunohistochemical analysis of formalin-fixed tissues of gastric cancer. Results: Expression of COX-2 showed diffuse staining in the cytoplasm of tumor cells, however, no staining in normal epithelial cells. Of the 108 tumors examined, 71 (65%) were positive for COX-2 expression, the VEGF-positive cases numbered 43 of 108 cases (39.8%). The intensity of COX-2 expression did not correlate with any clinicopathological characteristics. The positive rate of VEGF expression in COX-2-positive cases was significantly higher than in COX-2-negative ones (47.9% vs. 24.3%, P < 0.05). MVD in COX-2-positive cases was significantly higher than in COX-2-negative ones (22.0 ± 7.8 vs. 18.5 ± 7.5/1mm²; P < 0.05). Conclusions: Our study provides evidence that COX-2 is closely related with angiogenesis.