Chemoprevention of carcinogenesis in familial tumors.

Among familial cancers, chemoprevention has been studied for familial adenomatous polyposis, hereditary nonpolyposis colorectal cancers, and familial breast cancers. This report reviews the studies on chemoprevention in familial adenomatous polyposis. A large number of clinical trials have been performed using sulindac, a non-steroidal anti-inflammatory drug (NSAID). Sulindac reduces the size and number of large-bowel polyps. However, as yet, it cannot be used for this indication in the clinical setting, because of the frequent occurrence of serious gastrointestinal side effects, and there are a number of patients in whom aggressive tumors developed despite a reduction in the size of polyps. Studies of cyclooxygenase-2 (COX-2) selective inhibitors, with minimal side effects on the digestive tract, are showing promising results. In addition to NSAIDs, clinical trials have been performed using vitamins and dietary components. These show minimal side effects, but their efficacy is still insufficient for clinical use, and further studies are anticipated.