Prevention and inhibition of oral cancer in the hamster buccal pouch model associated with carotenoid immune enhancement.

Beta carotene, canthaxanthin, and a carotenoid mixture from an extract of algae were shown to prevent or inhibit the gross development of squamous cell carcinoma induced in the hamster buccal pouch by 7,12-dimethylbenz(a)anthracene. The carotenoids, dissolved in mineral oil, were administered by oral ingestion on days alternate to the carcinogen. Animals fed similar amounts of canthaxanthin, beta carotene or algae extract exhibited a statistically significant reduction in the development of tumors, both in number and size. The feeding of carotenoids, besides inhibiting gross tumor development, also produced a histologically unique picture. Microscopic areas of dysplasia, carcinoma in situ histologically unique picture. Microscopic areas of dysplasia, carcinoma in situ, or early carcinoma showed areas of tumor lysis and an inflammatory infiltrate consisting of lymphocytes and histiocytes. Characterization of this infiltrate disclosed a significant increase in cytotoxic lymphocytes, and cytotoxic macrophages producing tumor necrosis factor alpha. To confirm the presence of cytotoxic lymphocytes and macrophages a 51Cr release assay was performed. The results indicate that the immune response of the hamster was directed to the developing areas of dysplasia and carcinoma and was associated with the observations of prevention and inhibition of the growth of oral squamous cell carcinoma.