Cyclooxygenase inhibitors: drugs for cancer prevention.

Evidence that chronic intake of non-steroidal anti-inflammatory drugs, especially aspirin, prevents cancer development continues to accumulate. The data are particularly convincing for colorectal cancer; however, because of well-known side effects, they cannot routinely be recommended for this purpose. An appreciation of the mechanisms that underlie their anti-cancer effects might permit the development of safer agents. Intensive investigation has led to the characterization of several potential chemopreventive mechanisms of action of these drugs. Antineoplastic actions could result from effects on overlapping processes in the different cell-types that comprise tumors, such as epithelial and stromal cells.