Factors Influencing Experimental Carcinogenesis in the Hamster Cheek Pouch

¹ Department of Pathology and Division of Dental Research, University of Rochester, School of Medicine and Dentistry, Rochester, New York

1. Standardized experimental techniques for chemical carcinogenesis in the hamster cheek pouch are presented.

2. Under the conditions of the experiments described here, the tissues of the cheek pouch of old hamsters are more resistant to carcinogenic stimuli than those of young hamsters. No difference in rate of carcinogenic response is seen between the ages of 3 and 9 weeks. Five weeks appears to be the ideal age for hamsters used for experimental oral carcinogenesis from the standpoint of ease of manipulation and tumor production.

3. Five-tenths per cent concentration of 9,10-dimethyl-1,2-benzanthracene is the optimal concentration for the rapid production of malignant tumors in the hamster cheek pouch. This concentration produces maximum tumor response with minimum latent period, with no loss of animals due to toxicity; 0.1 per cent and 0.05 per cent concentrations will produce graded submaximal responses in tumor production.

4. A shorter latent period is required for tumor development in animals exposed to a carcinogen three times per week than in those receiving the carcinogen twice weekly. A smaller total dose is required to produce tumors in all animals when the carcinogen is applied twice each week than when given three times weekly.

5. The response of the hamsters to the repeated application of the carcinogenic hydrocarbon 9,10-dimethyl-1,2-benzanthracene is not related to the sex of the animals under the conditions of the experiments presented here.

6. Conditions of caging (three or four hamsters per cage) had no apparent effect on the experimental results obtained in the experiments reviewed here.