背景：流行病学调查发现长期使用非甾体类抗炎药（NSAIDs）的患者结肠癌发病率明已下降。NSAIDs能抑制环氧合酶（COX），而COX-2在结肠癌的发生、发展中起一定作用。目的：调查COX-2蛋白在胃癌组织中的表达。方法：用免疫组化半定量方法检测COX－2和COX-1蛋白在胃癌及相应正常组织中的表达。结果：97．1％（33／34）的胃癌组织中有COX-2蛋白表达，其强度明显高于正常胃窦粘膜，分化型胃癌的表达强度明显高于差分化型，进展期胃癌和有淋巴结转移者的表达亦增强；胃体腺、肠化上皮和间质细胞中可见COX-2蛋白表达。COX-1蛋白在正常胃窦粘膜、胃癌和癌旁组织的间质细胞中显低强度表达。结论：COX-2可能在胃癌的发生、分化和浸润转移中起作用。 BACKGROUND: Epidemiological studies have found that the incidence of colon cancer in patients with long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) has decreased. NSAIDs can inhibit cyclooxygenase (COX), and COX-2 plays a role in the occurrence and development of colon cancer. Objective: To investigate the expression of COX-2 protein in gastric cancer. Methods: Semiquantitative immunohistochemistry was used to detect the expression of COX-2 and COX-1 protein in gastric cancer and its normal tissues. RESULTS: COX-2 protein expression was found in 97.1% (33/34) of gastric cancer tissues, and its intensity was significantly higher than that of normal gastric antral mucosa. The expression intensity of differentiated gastric cancer was significantly higher than that of differential type, and advanced gastric cancer was associated with The expression of lymph node metastasis was also enhanced; COX-2 protein expression was observed in gastric gland, intestinal epithelial and stromal cells. COX-1 protein was expressed at low intensity in normal gastric antral mucosa, gastric cancer and adjacent tissue of mesothelial cells. Conclusion: COX-2 may play a role in the occurrence, differentiation and invasion and metastasis of gastric cancer.