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Vitamin A is essential for normal growth and development.Epidemiology andlaboratory studies suggest that decreased vitamin A levels and defective metabo-lism/action may contribute to the genesis of certain cancers.Based on thisinformation,natural and synthetic derivatives of vitamin A (retinoids) have beenused for chemoprevention of cancer.Retinoids have had some success in thechemoprevention of leukoplakia and in the decreased incidence of second prima-ries in head and neck cancer.There is little information on biomarkers that can beused to assess the efficacy of the chemopreventive activity of retinoids.Theability of retinoids to induce RARb has been consistently shown to correlate withthe response of cells and tissues to retinoic acid,but few other biomarkers havebeen certified as indicators of retinoid activity.In light of the failure of the ATBCand CARET clinical intervention trials for chemoprevention of lung cancer,greateruse of animal models for chemoprevention studies is necessary.The potentialcombination of phytochemicals that inhibit DNA methyltransferase activity withretinoids holds promise for more effective chemoprevention of retinoid-unrespon-sive premalignant lesions.
Vitamin A is essential for normal growth and development. Epidemiology and laboratory studies suggest that decreased vitamin A levels and defective metabo-lism / action may contribute to the genesis of certain cancers. Based on this information, natural and synthetic derivatives of vitamin A (retinoids) have beenused for chemoprevention of cancer. Retinoids have had some success in thechemoprevention of leukoplakia and in the decreased incidence of second prima-ries in head and neck cancer. There is little information on biomarkers that can beused to assess the efficacy of the chemopreventive activity of retinoids The ability of retinoids to induce RARb has been consistently shown to correlate with the response of cells and tissues to retinoic acid, but few few biomarkers havebeen certified as indicators of retinoid activity. Light of the failure of the ATBC and CARET clinical intervention trials for chemoprevention of lung cancer, greateruse of animal models for chemoprevention studies is neces sary. The potentialcombination of phytochemicals that inhibit DNA methyltransferase activity withretinoids holds promise for more effective chemoprevention of retinoid-unresponsive smalsant lesions.