ANTIOXIDANT AGENTS AND COLORECTAL CARCINOGENESIS - ROLE OF BETA-CAROTENE, VITAMIN-E AND VITAMIN-C

In consideration of findings reported in the literature and of our stu dy, we examined the correlation between antioxidants (beta-carotene, v itamin C, vitamin E) and colorectal carcinogenesis, Although diagnosti c progress has been made in the last decades, no significant improveme nts in death rates have been achieved in the western world. Exogenous factors might be responsible for a complex alteration process of norma l colonic mucosa into adenoma and carcinoma, Free radicals and reactiv e oxygen metabolites, due to increased production or to reduced inacti vation, following a decrease in the antioxidant burden in the mucosa, might cause damage to DNA, thereby resulting in genetic alterations. T his might represent the cause of the transformation process: normal mu cosa--> adenoma--> carcinoma, In a prospective study, we observed a re duction of beta-carotene levels in normal colonic mucosa in patients w ith polyps and colorectal cancer, We also showed that beta-carotene su pplementation raises levels of this micronutrient in the colonic mucos a of these patients, Findings from the literature and our trials show a significant decrease in the antioxidant capacity of colorectal mucos a in patients affected by colorectal cancer, although there is a signi ficant interindividual variability. Such results suggest a possible ch emopreventive role of antioxidant agents in colorectal cancer.