Neuroendocrine tumors of the pancreas (islet cell tumors) are much less common than tumors arising from the exocrine pancreas. Reports often indicate that there are about two to three thousand cases diagnosed in the U.S. each year – although autopsy indicates that there may be a higher incidence of these islet cell tumors than are diagnosed.
About 75% of these tumors are “functioning.” That is they are found to be producing symptoms related to one or more of the hormone peptides that they secrete. About one quarter of islet cell tumors do not produce symptoms related to hormone secretion and thus are termed non-functioning. The predominant hormone peptide being secreted gives the functioning islet cell tumor its name. There are a surprising number of these hormonal peptides that islet cell tumors have been found to secrete; some are not even related to the pancreas. This array includes insulin, gastrin, glucagon, somatostatin, neurotensin, pancreatic polypeptide (“PP”), vasoactive intestinal peptide (“VIP”), growth hormone releasing factor (“GRF”), ACTH and others. Some of these are very rare.