title: Mammary carcinoma induced by oral administration of ethyl methanesulphonate. Determination of some of the parameters affecting tumor induction.
abstract: The carcinogenic activity of ethyl methanesulphonate (EMS), an alkylating agent and a potent mutagen, was examined in Wistar King A and Sprague Dawley rats following oral administration. In the Wistar King A rats, mammary carcinomas were detected in all of the young female rats by the 32nd week after initiation of the experiment. To determine the optimal experimental conditions for the rapid and invariable induction of mammary carcinomas, the relationship among age, sex, strain of the rats and concentration and duration of EMS administration, and tumor production was investigated. The tumor incidence was higher in the younger female rats and the Wistar rats were more susceptible than Sprague-Dawley rats. Mammary carcinomas were also induced in the younger male rats. In addition, concommitant production of renal tumors occurred by the 40th week in young rats administered 10(-2) M or 2 x 10(-2) M of EMS solution, while renal and uterine tumors developed concommitantly in the older female rats given 3 x 10(-3) EMS by the 56th week. Histologically, the prevailing features of tumors were infiltrating ductal adenocarcinoma in the mammary glands, mesenchymal tumor in the kidney, and leiomyosarcoma in the uterus. Methyl methanesulphonate, an analogue of EMS, did not induce tumors in any organs.
mesh_terms: D000375:Aging; D000818:Animals; D005020:Ethyl Methanesulfonate; D005260:Female; D008297:Male; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced* / Q000473:pathology; D051381:Rats; D011919:Rats, Inbred Strains; D012737:Sex Factors; D013045:Species Specificity
chemical_list: D005020:Ethyl Methanesulfonate