Effects of various prostaglandin synthesis inhibitors on pancreatic carcinogenesis in hamsters after initiation with N-nitrosobis(2-oxopropyl)amine.

The effects of prostaglandin synthesis inhibitors on development of N-nitrosobis(2-oxopropyl)amine (BOP)-initiated pancreatic tumors were investigated. Female Syrian golden hamsters were given five weekly s.c. injections of BOP (10 mg/kg body weight) during the first 5 weeks and then given 20 p.p.m. indomethacin in the drinking water, 0.25% phenylbutazone in the diet, 1% aspirin in the diet, or no treatment (control group). The resultant incidence of pancreatic carcinoma at week 32 was significantly lower (P less than 0.05) in animals receiving phenylbutazone (36.8%) than in the controls (71.4%) and the numbers of carcinomas per hamster were significantly reduced by indomethacin (0.63) and phenylbutazone (0.58) treatment compared with the control group value (1.29). Aspirin also showed a tendency to decrease pancreatic tumor incidence, but this was not significant. Thus, prostaglandin synthesis inhibitors reduce the development of pancreatic cancer when administered during the post-initiation phase in this animal model.