Insulin and its potential role in pancreatic cancer: histomorphological and immunoistochemical study on post mortem pancreatic material

Introduction Several studies suggest that correlation exists between diabetes and different types of cancer. However the temporal association between diabetes and pancreatic cancer is controversial. Some evidence suggests the hypothesis that insulin can promote neoplastic transformation, cancer growth and progression of this neoplasia. The aim of this work was to investigate the relationship between insulin and pancreatic cancer, acquiring new data on insulin detected in pancreatic tissue by dosing insulin concentrations directly in samples of human pancreas. Materials and methods In the period from January 2012 to November 2015, in collaboration with the Pathology Service and the Geriatric Surgery Unit at "Università Campus Bio-Medico" and the Institute of Human Anatomy at the "Università Cattolica del Sacro Cuore" of Rome, 90 autopsies were performed and three samples of pancreatic tissue were taken (head, body and tail) for each case. In order to quantify beta-cell presence in tissue samples, standard immunohistochemical staining was employed, and semi-quantitative and quantitative methods were used. Results The majority of islets and insulin in the homogenized tissue are found in the tail of the pancreas. Since the large majority of pancreatic cancers are detected in the head and body of the gland, our data, although limited by the small sample size, seem to suggest that irrespective of diabetes and associated factors, insulin “per se” should not be considered as a promoting factor for pancreatic cancer. Conclusion We demonstrate that insulin assay in homogenized pancreatic tissue and insulin immunohistochemical staining from cadaver donors after a few hours of death are feasible, despite the known fact that this organ is exposed, more than others, to the local autolytic action of enzymes. The technique has proved to be reproducible and useful to achieve semiquantitative results. We conclude that it is unlikely that insulin may promote pancreatic cancer.