Tumor markers in neuroendocrine tumors

Most neuroendocrine tumors produce and secrete a multitude of peptide hormo nes and amines. Some of these substances cause a specific clinical syndrome : carcinoid, Zollinger-Ellison, hyperglycemic, glucagonoma and WDHA syndrom e. Specific markers for these syndromes are basal and/or stimulated levels of urinary 5-HIAA, serum or plasma gastrin, insulin, glucagon and vasoactiv e intestinal polypeptide, respectively. Some carcinoid tumors and about one third of endocrine pancreatic tumors do not present any clinical symptoms and are called 'nonfunctioning' tumors. Therefore, general tumor markers su ch as chromogranin A, pancreatic polypeptide, serum neuron-specific enolase and subunits of glycoprotein hormones have been used for screening purpose s in patients without distinct clinical hormone-related symptoms. Among the se general tumor markers chromogranin A, although its precise function is n ot yet established, has been shown to be a very sensitive and specific seru m marker for various types of neuroendocrine tumors. This is because it may also be elevated in many cases of less well-differentiated tumors of neuro endocrine origin that do not secrete known hormones. At the moment, chromog ranin A is considered the best general neuroendocrine serum or plasma marke r available both for diagnosis and therapeutic evaluation and is increased in 50-100% of patients with various neuroendocrine tumors. Chromogranin A s erum or plasma levels reflect tumor load, and it may be an independent mark er of prognosis in patients with midgut carcinoids. Copyright (C) 2000 S. K arger AG, Basel.