[Epidemiological studies for evaluating the role of cyclooxygenase in chemoprevention of malignant tumors].

Researchers have found dramatically elevated cyclooxygenase-2 (COX-2) expression in a striking number of malignant and premalignant conditions. Epidemiological evidence is in favour of aspirin and non steroidal anti-inflammatory drugs (NSAIDs) preventing certain tumors. More than 100 years after aspirin, an inhibitor of cyclooxygenase-1 and -2, was first used for the treatment of rheumatic diseases, analogues were developed for the same and other inclinations that now are available for clinical use. These new drugs were designed to specifically inhibit cyclooxygenase-2. They are thought having equal efficacy, but significantly fewer gastrointestinal side effects than the non steroidal anti-inflammatory drugs that nonspecifically inhibit the cyclooxygenase enzymes. After the selective cyclooxygenase-2 inhibitor celexocib has been licensed in the USA for the chemoprevention of colorectal cancer, there is hope in this new class of agents to prevent other cancers as well. Epidemiological studies suggest a decreased incidence of cancers of the colon, rectum, oesophagus, and stomach in regular users of non steroidal anti-inflammatory drugs; while the evidence from observational studies for other tumors is not yet strong enough, the broad range of clinical trials that are currently under their way will help establish the drugs' effectiveness in preventing or treating a variety of different types of cancer.