NEGLIGIBLE RISK FOR PANCREATIC CANCER AMONG TYPE 1 DIABETICS

Abstract

Background & Aims: Endocrine islets are possibly involved in the development of pancreatic cancer in three different ways. First, insulin is produced in the beta cells of pancreatic islets and insulin has been suggested to drive pancreatic carcinogenesis. Second, pancreatic carcinogens may be processed in endocrine pancreatic islets before having carcinogenic effects on precursor pancreatic cancer cells. Third, endocrine islets may harbour the precursor cells of pancreatic cancer. According to these hypotheses, a decreased risk for pancreatic cancer is expected to be found in type 1 diabetes, which is caused by destruction of insulin-producing cells in the islets. Methods: All cases with pancreatic cancer in the Swedish Cancer Register between 1997 and 1999 were crosschecked with respect to occurrence of insulin-dependent diabetes in the Swedish Inpatient Register. The cases with both diagnoses were compared with age- and gender-matched controls that had insulin-dependent diabetes but no pancreatic cancer. Results: There were 31 cases with both insulin-dependent diabetes and pancreatic cancer but none of them had type 1 diabetes. In contrast, type 1 diabetes was found in 19% (11/59) of the insulin-dependent diabetic controls. The relative risk for pancreatic cancer among type 1 diabetics was thus 0.00, 95% CI 0.00-0.83, p = 0.03. Conclusions: Type 1 diabetes is associated with a decreased risk of pancreatic cancer. Pancreatic islets are crucial for the pathogenesis of pancreatic cancer.