Role of vitamins C and E as chemopreventive agents in the hamster cheek pouch treated with the oral carcinogen‐DMBA

OBJECTIVE: To evaluate the role of vitamins C and E as chemopreventive agents in oral carcinogenesis by optical and ultrastructural studies. MATERIALS AND METHODS: The cheek pouch of male hamsters was treated with the oral carcinogen, dimethylbenz(a)anthracene (DMBA), to induce multiple tumour formation. Vitamins C and E were applied either singly or in combination as a chemopreventive agent. Paraffin and resin-embedded sections of the hamster cheek pouch were studied optically and ultrastructurally. RESULTS: The epithelium of control hamsters showed hyperorthokeratosis and parakeratosis, but did not develop well differentiated squamous cell carcinoma (WDSCC). Ninety percent of the animals treated with DMBA alone showed WDSCC while 10% of the animals developed papillomas. There was also a marked increase in the number of cells undergoing mitosis in this group. A reduction in the yield (1.1 tumour/animal) and rate 60-80% of squamous cell carcinomas but not of papillomas (2.0 papillomas/animal) was observed in groups VI-VIII treated with DMBA and vitamins C and E singly or in combination as compared to those of DMBA only. In animals treated with DMBA plus vitamins C and E, statistical significant decrease in the number of animals with tumours and mitotic basal cells was observed when compared with the DMBA treated group. Control animals showed normal ultrastructural morphology while tumour-bearing animals showed basal lamina in a discontinuous, fragmented, broken and diffused basement membrane, with diminished lamina densa, fewer hemidesmosomes and invagination of the basal cell cytoplasmic processes in the subepithelium. CONCLUSION: These results indicate that vitamin E singly or in combination with vitamin C plays a role in the inhibition of tumour cell growth.