Historical background and epidemiology

Abstract

The discovery of the endocrine pancreas was made in 1869 by Paul Langerhans when he was at the end of his medical studies. He described a cluster of clear cells in a small islet, but he was disappointed not to be able to explain the role of these cells. Their role in diabetes mellitus was suggested later by E. Laguesse and by E.L. Opie. Tumors resembling these cells had been reported a century ago. Since then, different types of pancreatic neuroendocrine tumors (PanNETs) have been described; most of them are not associated with a clinical syndrome (the so-called nonfunctioning PanNETs), while PanNETs that manifest a clinical syndrome (“functioning PanNETs”) take their name from the hormone involved (insulinoma, gastrinoma, glucagonoma, VIPoma, and somatostatinoma). PanNETs represent 1.3-3 % of all pancreatic neoplasms and 7 % of all gastroenteropancreatic neuroendocrine tumors. The incidence differs according to the geographic area, gender, and race as well as between developed countries and undeveloped ones. While the number of exocrine pancreatic tumors diagnosed has remained steady, in the last few years, there has been an increase in the number of PanNETs observed, particularly in older people (>60 years). Now the prevalence of PanNETs accounts for more than 10 % of pancreatic tumors, reflecting the different behavior of the two entities. About 10 % of PanNETs are linked to hereditary syndromes, and, in these cases, the tumors occur at an earlier age.