Current Medical Controversies in Zollinger–Ellison Syndrome

<b>Purpose</b>: Zollinger-Ellison syndrome (ZES) is the most frequent, functional, malignant pancreatic neuroendocrine tumor syndrome (pNET), which is due to ectopic secretion of gastrin by a pNET/NET (i.e., gastrinomas) resulting in severe, refractory acid-peptic disease (ulcer, GERD). ZES has several unique management features, which lead to a number of unresolved controversies. <b>Areas covered</b>: Whereas both medical and surgical controversies exist, they have not been examined in detail for some time. This review contains an analysis of a number of the main current, medical controversies that are unresolved in ZES patients, including insights into the basis of these controversies and possible insights into their resolution from recent studies in patients with gastrinomas or from recent studies in other pNET syndromes or other neuroendocrine tumors (NETs). These include the following: controversies in the long-term control of acid secretion and acid antisecretory drug side-effects; controversies related to the difficulty in making the diagnosis of ZES; nonsurgical MEN1/ZES controversies related to the management of gastric carcinoids (Type II); nonsurgical MEN1/ZES controversies related to whether genotype-phenotype correlations exist in MEN1 patients including MEN1/ZES patients; nonsurgical MEN1/ZES controversies related to the roles of imaging/tumor localization in MEN1 patients for gastrinomas/pNETs in their initial/follow-up management; controversies related to the role of non-surgical tumor ablation for treatment of ZES/gastrinomas; and controversies related to medical treatment selection for advanced, metastatic disease in patients with ZES/gastrinomas/other malignant pNETs. <b>Conclusions</b>: In this paper, the basis for the development of each of these unique ZES-related controversies is discussed and insights into progress that could lead to their resolution are reviewed.