Early lesions during pancreatic carcinogenesis induced in Syrian hamster by DHPN or DOPN. I. Histologic, histochemical and radioautographic findings.

The early lesions which arise in the Syrian hamster pancreas prior to the appearance of carcinomas induced by treatment with the related carcinogens di-hydroxy-di-n-propyl nitrosamine or di-oxo-di-n-propyl nitrosamine were investigated in order to assess their roles in tumourigenesis. A sequence of events is proposed leading from ductal or ductular proliferations through regions of epithelial atypia (so-called dysplastic lesions) to carcinomas. This sequence appears distinct from that leading from ductular proliferations to benign multilocular cysts or cystadenomas. Radioautographic and histochemical evidence is presented supporting this proposal linking atypical proliferations but not cystic lesions with the induced carcinomas. Increase in the activity of glucose-6-phosphate dehydrogenase was established as being a good histochemical marker for early atypical proliferations during pancreatic carcinogenesis whereas gamma-glutamyl transpeptidase was found lacking in this respect. In addition, alteration in polysaccharide metabolism was observed during the development of the carcinomas.