Modulation by vitamin C of tumour incidence and inhibition in oral carcinogenesis

This study reports the mechanism of involvement of vitamin C in the pathogenesis of induced oral carcinogenesis in the hamster cheek pouch epithelium. This site was exposed to either DMBA singly or in combination with vitamin C or DMBA for 7 weeks followed by only vitamin C till tumour induction. Macroscopically, vitamin C reduces the epithelial tumour incidence in the hamster cheek pouch. Microscopically tumours induced by DMBA alone were well differentiated squamous carcinomas in all the animals, whereas those induced by DMBA plus vitamin C were papillary epidermoid carcinomas with minimal invasion. These observations suggest that vitamin C is capable of restricting the growth of the initiated cells and does not allow the invasion of the subepithelium. The mechanism of action of vitamin C in the process of restricting growth and invagination was clearly shown in ultrastructural pathology too. In vitamin C exposed tumours the dermal epidermal junction of the cheek pouch epithelium maintains basement membrane integrity, with the presence of cellular organelles and cytoskeletal structure of the cells.