Pancreatic carcinogenesis and naturally occurring pancreatic neoplasms of rats and mice in the NCI carcinogenesis testing program.

Over two hundred chemicals were examined in a two year rodent bioassay system for possible carcinogenicity. Of these, only nitrofen significantly increased the incidence of neoplasms of the exocrine pancreas of rats or mice (female Osborne-Mendel rats); azinphosmethyl was the only agent tested which significantly increased the incidence of islet-cell tumors of rats or mice (male Osborne-Mendel rats). The use of the rat (Osborne-Mendel or Fischer 344) and mouse (B6C3F1) as models for the detection of chemically-induced pancreatic neoplasms also was investigated. The incidences of specific neoplasms of the exocrine or endocrine pancreas produced by all chemicals tested were combined and compared with the combined incidences of similar neoplasms in control animals in order to increase the sensitivity of the test. The data obtained through this procedure suggests that the male rat may be a good, sensitive model for the detection of islet-cell tumors.