Experimental esophageal carcinoma in mastomys. A preliminary report
Soga, J.; Tajima, K.; Tanaka, O.; Kawaguchi, M.; Fujimaki, M.
Acta Medica et Biologica 22(3-4): 119-132
1975
ISSN/ISBN: 0567-7734 PMID: 1199679 Document Number: 93355
Experimental esophageal carcinomas, mostly of a squamous cell type, nonkeratinizing and keratinizing, from in-situ to invasive and metastatic nature were produced at high rates in 87.0%, or 20 of 23 mastomys, and 91.7%, or 22 of 24 Donryu rats following oral administration of N-n-butyl-N-nitrosourethan (BNUR) at a dose of 300 ppm daily for 17-19 wk for mastomys and 23 wk for Donryu rats, the total estimated dose of BNUR administered being .apprxeq. 5 g/kg per animal. Identical lesions were also encountered in the forestomach, pharynx and oral cavity of both species. No significant species difference between mastomys and Donryu rats was evident in the occurrence rate of esophageal carcinoma. These malignant lesions were constantly of multiple growth at the dose of BNUR used and after BNUR administration was completed. Production of multiple hyperkeratotic polyps, unusual in the human esophagus, was a common feature in the esophagus and forestomach of both species. Histologic features and a high incidence of these esophageal lesions guaranteed the usefulness of these experimental lesions as a model of the investigation of human esophageal carcinoma to a limited extent. A histologic comparative study of the normal esophagus of man, mastomys and Donryu rats indicated that the esophageal epithelium of the latter 2 species was identical to the epidermis of the human skin rather than to the epithelium of the human esophagus. Frequent occurrence of hyperkeratotic polyps and keratoacanthomatous lesions was accounted for on the basis of this fact. Since no neoplastic lesions were encountered in the other organs and tissues in the present study, BNUR is considered a specific carcinogen for the esophagus and forestomach, along with the pharynx and oral cavity of rodents.