Effect of streptozotocin diabetes on development of nitrosamine-induced pancreatic carcinoma when diabetes induction occurs after nitrosamine exposure

Diabetes mellitus has been suggested as a possible risk factorfor the development of pancreatic cancer in humans. Previousstudies in our laboratory have shown, however, that streptozotocin(STZ) diabetes inhibits the development of cancer of the exocrinepancreas in hamsters when STZ is administered prior to treatmentwith the pancreatic carcinogen N-nitrosobis(2-oxopropyl)amine(BOP). It has been reported by others that the concurrent administrationof BOP and STZ enhances pancreatic carcinogenesis in hamsters.The purpose of the present study was to determine the effectof STZ diabetes on the development of BOP-induced pancreaticcarcinoma when STZ is given following exposure to BOP. Groupsof Syrian golden hamsters were treated with either BOP only(single s.c. injection, 40 mg/kg body wt at week 0), BOP (singles.c. injection, 40 mg/kg body wt at week 0) plus STZ (50 mg/kgbody wt x3 daily i.p. doses at weeks 10, 20 or 30), STZ only(50 mg/kg body wt x3 daily i.p. doses at weeks 10, 20 or 30),or neither BOP nor STZ. The experiment was terminated at 40weeks after BOP treatment. No significant difference was seenin the incidence of pancreatic cancer between those animalsreceiving BOP only at week 0 and those receiving BOP at week0 plus STZ at weeks 10, 20 or 30 of the study. The results wouldappear to indicate that STZ diabetes, established after BOPtumor initiation, plays no apparent role in the modulation ofpancreatic carcinogenesis.