THE BIOLOGICAL RELEVANCE OF GASTRIC NEUROENDOCRINE TUMORS

Gastric neuroendocrine tumors were originally thought to have a low in cidence (three percent). Since endoscopic diagnostic procedures have b ecome clinical routine, they are now found more frequently (relative i ncidence up to 41 percent). In recent years, classifications have been developed that attempt to consider the biological relevance of these tumors. Four types of gastric neuroendocrine tumor may be distinguishe d: Type 1 gastric neuroendocrine tumor is most common. It is associate d with chronic atrophic fundus gastritis, hypergastrinemia and often w ith pernicious anemia. Usually it is multicentric and smaller than one cm, does not produce any symptoms and has an excellent prognosis. Typ e 2 gastric neuroendocrine tumor is second in frequency. It has no ass ociation with other diseases, is solitary and has no predilection for a particular localization It may be larger than 1 cm, produce a carcin oid syndrome or Zollinger-Ellison syndrome and have a metastasis rate of up to 30 percent. Type 3 gastric neuroendocrine tumor is rare and a lways associated with Zollinger-Ellison syndrome and multiple endocrin e neoplasia type I. It occurs as multiple lesions in the gastric body fundus and has a lower metastatic rate than type 2 gastric neuroendocr ine tumor. Type 4 gastric neuroendocrine tumor corresponds to a small- cell carcinoma.