Gastrinoma

Excerpt

Gastrinomas are neuroendocrine neoplasms (NENs), that occur primarily in the duodenum and pancreas, which ectopically secrete gastrin, resulting in the Zollinger-Ellison syndrome (ZES), which is due to marked hypersecretion of gastric acid causing severe gastro-esophageal peptic disease. ZES patients have two management problems that must be dealt with: control of the acid hypersecretion and control of the gastrinoma, which is malignant in 60-90% of cases. Most gastrinomas are sporadic, but 20-25% of patients have it as part of the Multiple Endocrine Neoplasia-type 1 syndrome (MEN1), an autosomal dominant disorder characterized by endocrine tumors/hyperplasia of multiple endocrine organs (parathyroid> pancreatic islets>pituitary>adrenal). It is important to identify those with ZES/MEN1 as their management differs from those with sporadic disease. Acid hypersecretion is now controlled medically both acutely and long term, with proton pump inhibitors (PPI) the drugs of choice. In patients with sporadic ZES, after detailed imaging with cross-sectional imaging and somatostatin receptor imaging (SRI), resection of the gastrinomas should be considered whenever possible, with cures reported in 20-45% of patients. The role of surgical resection of the gastrinomas in MEN1/ZES is controversial and it is generally recommended it be reserved for patients with tumors>1.5/2 cm because of the multiplicity of small gastrinomas resulting in very low cure rates. The diagnosis of ZES requires demonstrating fasting hypergastrinemia in the presence of inappropriate acid secretion (pH<2), however, because of the widespread use of PPIs and the lack of gastric acid testing, the diagnosis of ZES is becoming more difficult and referral to a specialty group is frequently required. Patients with advanced metastatic disease are treated as other patients with advanced NENs including with somatostatin analogues, chemotherapy, everolimus, sunitinib, liver directed therapies, and peptide radio-receptor therapy (PRRT) with radiolabeled somatostatin analogues. For complete coverage of all related areas of Endocrinology, please visit our on-line FREE web-text, WWW.ENDOTEXT.ORG.