Cycles of repeated augmentation pressure in rapid production of pancreatic and cholangiocellular carcinomas in hamsters initiated with N-nitrosobis(2-oxopropyl)amine.

We previously reported a rapid production model for pancreatic carcinoma development in Syrian hamsters incorporating the principle of selection by resistance to cytotoxicity. In the present experiment, the efficacy of repeated augmentation pressure with regard to generation of pancreatic lesions in hamsters initiated with N-nitrosobis(2-oxopropyl)amine (BOP) was investigated. Forty-eight female Syrian golden hamsters were divided into four groups according to the frequency of augmentation pressure. Group 1 received 70 mg/kg body weight of BOP and three injections of 20 mg/kg BOP. Groups 2-4 received 70 mg/kg BOP followed by one, two or three cycles of augmentation pressure consisting of dl-ethionine on sugar and salt diet, l-methionine and 20 mg/kg BOP. Hamsters were killed 10 weeks after the beginning of the experiment and the resultant incidences of pancreatic carcinomas from groups 1-4 were 0, 30, 50 and 46.2% respectively, the numbers of pancreatic carcinomas increasing with the frequency of augmentation pressure. A 46.2% yield of cholangiocarcinomas was also observed in group 4. The model should be useful for investigation of potential modulating factors since large numbers of lesions can be induced within a total experimental period of only 10 weeks.