COX-2 inhibition and colorectal cancer

Abstract

Mortality in patients with advanced colorectal cancer (CRC) remains high. Epidemiologic studies show that individuals taking nonselective, nonsteroidal anti-inflammatory drugs, including aspirin, have a significant reduction in CRC mortality, compared with those not taking these agents. The recent characterization of cyclooxygenase-1 and -2 (COX-1 and COX-2) isoforms has led to an expanded understanding of how nonsteroidal anti-inflammatory drugs may help prevent polyp formation. Cyclooxygenase enzymes are required for the conversion of arachidonic acid to prostaglandins. COX-2 mediates the inflammatory effects of COX activity, is induced by a wide spectrum of growth factors and proinflammatory cytokines, and is overexpressed in numerous premalignant and malignant lesions, including CRC. Treatment with the selective COX-2 inhibitor celecoxib has shown promising results in the prevention of CRC. Numerous studies show that this COX-2 selective inhibitor is a potent suppressor of colon polyps both in animal models for familial adenomatous polyposis and in patients with this condition. This has led to the US Food and Drug Administration approval of celecoxib for the treatment of patients with familial adenomatous polyposis. The role of celecoxib in cancer treatment is still evolving. Recent studies have identified a potential benefit for adding celecoxib to standard CRC chemotherapy regimens to increase their efficacy and reduce their associated toxicity.