Chemoprevention of aerodigestive tract cancers.

Epithelial cancers are a major worldwide health problem. Since the mid-1970s, advances in multidisciplinary cancer therapeutics have only slightly improved the mortality rate from epithelial malignancies. Chemoprevention is the use of specific natural or synthetic chemical agents to reverse, suppress, or prevent progression to invasive cancer. Chemopreventive medicine is based on translating basic biologic research into clinical chemical interventions, thus attempting to impede carcinogenesis. Its principles build on the concepts of field cancerization (diffuse epithelial injury that results from carcinogen exposure) and multistep carcinogenesis (a stepwise accumulation of cellular and genetic alterations that progress to cancer). Chemoprevention targets the carcinogenic process at earlier and potentially more reversible stages, focusing on the inhibition of one or many steps in the progression towards cancer. Strategies of chemoprevention include primary prevention in groups at high risk, reversal of premalignant lesions, and prevention of second primary tumors.