Cancer chemoprevention: principles and prospects

Abstract

Cancer chemoprevention can be defined as prevention of cancer by the administration of one or more chemical entities, either as individual drugs or as naturally occurring constituents of the diet. For several reasons, chemoprevention has received growing consideration as a means of cancer control. In the USA, the 5 year survival rate of cancer patients is currently 51 % overall (1). Among those organ sites with exceptionally low 5 year survival rates are lung (13%), ovary (39%), stomach (16%), esophagus (9%) and pancreas (3%) (1). Clearly, the considerable advances that have occurred in earlier detection and treatment of cancer have done little to improve the prognosis for patients diagnosed with cancer at certain organ sites. Thus, the aggressive prevention of cancer should be a cornerstone of any cancer control policy. Primary cancer prevention requires removal of exposure of individuals to etiologic agents. However, numerous subpopulations at high risk for certain types of cancer may already have received considerable exposure to such agents, and many human cancers cannot be ascribed to specific etiologic agents. Thus, preventative strategies that do not require prior knowledge of specific etiologic factors have great appeal. Additionally, the cost of chemopreventative programs in a given population should be considerably less than the actual health care costs incurred by any fraction of that population that develops cancer. Hence, chemoprevention of cancer may become a major weapon in the anticancer arsenal.