Cancer chemoprevention by dietary phytochemicals: a mechanistic viewpoint

Chemoprevention refers to the use of non-toxic chemical agents to prevent neoplastic development by inhibiting, delaying, or reversing multi-stage carcinogenesis, The primary goal of chemoprevention research is to identify or produce effective agents and strategies for clinical trials go be applied to normal or high-risk human populations, A large number of compounds have been tested for their possible chemopreventive activities, and it is of interest to note that many of them are naturally occurring substances. Thus, a variety of plant and vegetable constituents, particularly those included in our daily diet, have been found to possess substantial protective properties against experimental carcinogenesis, These substances, collectively known as dietary phytochemicals, exert their chemopreventive effects by influencing specific step(s) of multi-stage carcinogenesis: some inhibit metabolic activation or enhance detoxification of carcinogens, others interfere with covalent interactions between ultimate electrophilic carcinogens and the target cell DNA and still others may exert anti-promotion or anti-progression effects. Mechanism-based interventions by use of safe dietary phytochemicals may provide one of the most practical and promising cancer chemopreventive strategies.