Cyclooxygenase-2 overexpression correlates with tumour recurrence, especially haematogenous metastasis, of colorectal cancer

Epidemiological studies have demonstrated that nonsteroidal anti-inflammato ry drugs (NSAIDs), known to inhibit cyclooxygenase (COX), reduce the risk o f colorectal cancer. COX is a key enzyme in prostaglandin biosynthesis, and two isoforms of COX, COX-1 and COX-2, have been identified. Recently COX-2 has been reported to frequently overexpress in colorectal neoplasms and to play a role in colorectal tumorigenesis and tumour progression. In this st udy, using immunohistochemistry, we examined COX-2 expression in advanced h uman colorectal cancer and its correlation with clinicopathological feature s. COX-2 expression was observed mainly in the cytoplasm of cancer cells in all the specimens examined, but some stromal cells and endothetial cells w ere also stained. According to the grade of COX-2 expression of the cancer cells, patients were divided into high- and low-COX-2 expression groups. Hi gh-COX-2 expression significantly correlated with tumour recurrence, especi ally haematogenous metastasis. These results suggest that a selective COX-2 inhibitor can be a novel class of therapeutic agents not only for tumorige nesis but also for haematogenous metastasis of cololectal cancer. To our kn owledge, this is the first report on the correlation between COX-2 overexpr ession and recurrence of colorectal cancer. (C) 2000 Cancer Research Campai gn.