Gastrinomas are a type of pancreatic endocrine tumor Overview of Pancreatic Endocrine Tumors Pancreatic endocrine tumors arise from islet and gastrin-producing cells and often produce many hormones. Although these tumors develop most often in the pancreas, they may appear in other organs... read more that arises from islet cells but can also arise from the gastrin-producing cells in duodenum and other sites in the body. Gastrinomas occur in the pancreas or duodenal wall 80 to 90% of the time. The remainder occur in the splenic hilum, mesentery, stomach, lymph node, or ovary. About 50% of patients have multiple tumors.
Gastrinomas usually are small (< 1 cm in diameter) and grow slowly. About 50% are malignant.
About 40 to 60% of patients with gastrinoma have multiple endocrine neoplasia Overview of Multiple Endocrine Neoplasias (MEN) The multiple endocrine neoplasia (MEN) syndromes comprise 4 genetically distinct familial diseases involving adenomatous hyperplasia and malignant tumors in several endocrine glands. MEN 1 involves... read more , a syndrome that is associated with neuroendocrine tumors of the pancreas (eg, gastrinoma), pituitary adenomas Pituitary Tumors Most pituitary tumors are adenomas. Symptoms include headache and endocrinopathies; endocrinopathies result when the tumor produces hormones or destroys hormone-producing tissue. Diagnosis is... read more , and parathyroid hyperplasia.
Symptoms and Signs of Gastrinoma
Zollinger-Ellison syndrome typically manifests as aggressive peptic ulcer disease Peptic Ulcer Disease A peptic ulcer is an erosion in a segment of the gastrointestinal mucosa, typically in the stomach (gastric ulcer) or the first few centimeters of the duodenum (duodenal ulcer), that penetrates... read more , with ulcers occurring in atypical locations (up to 25% are located distal to the duodenal bulb). However, as many as 25% of patients do not have an ulcer at diagnosis. Typical ulcer symptoms Symptoms and Signs A peptic ulcer is an erosion in a segment of the gastrointestinal mucosa, typically in the stomach (gastric ulcer) or the first few centimeters of the duodenum (duodenal ulcer), that penetrates... read more and complications Complications A peptic ulcer is an erosion in a segment of the gastrointestinal mucosa, typically in the stomach (gastric ulcer) or the first few centimeters of the duodenum (duodenal ulcer), that penetrates... read more (eg, perforation, bleeding, obstruction) can occur. Diarrhea is the initial symptom in 25 to 40% of patients.
Diagnosis of Gastrinoma
Serum gastrin level
CT, scintigraphy, or positron emission tomography (PET) to localize
Gastrinoma is suspected by history, particularly when symptoms are refractory to standard acid suppressant therapy.
Serum gastrin level is the most reliable test. All patients have levels > 150 pg/mL (> 72 pmol/L); markedly elevated levels of > 1000 pg/mL (> 480 pmol/L) in a patient with compatible clinical features and gastric acid hypersecretion of > 15 mEq/hour establish the diagnosis. However, moderate hypergastrinemia can occur with hypochlorhydric states (eg, pernicious anemia, chronic gastritis, use of proton pump inhibitors), in renal insufficiency with decreased clearance of gastrins, in massive intestinal resection, and in pheochromocytoma.
A secretin provocative test may be useful in patients with gastrin levels < 1000 pg/mL (< 480 pmol/L). An IV bolus of secretin 2 mcg/kg is given with serial measurements of serum gastrin (10 minutes and 1 minute before, and 2, 5, 10, 15, 20, and 30 minutes after injection). The characteristic response in gastrinoma is a paradoxical increase in gastrin levels, the opposite of what occurs in patients with antral G-cell hyperplasia or typical peptic ulcer disease. Patients also should be evaluated for Helicobacter pylori infection Diagnosis Helicobacter pylori is a common gastric pathogen that causes gastritis, peptic ulcer disease, gastric adenocarcinoma, and low-grade gastric lymphoma. Infection may be asymptomatic or... read more , which commonly results in peptic ulceration and moderate excess gastrin secretion.
Once the diagnosis of gastrinoma has been established, the tumor or tumors must be localized. The first test is abdominal CT or somatostatin receptor scintigraphy, which may identify the primary tumor and metastatic disease. PET or selective arteriography with magnification and subtraction is also helpful. If no signs of metastases are present and the location of the primary tumor is uncertain, endoscopic ultrasonography should be done. Selective arterial secretin injection is an alternative.
Treatment of Gastrinoma
Surgical resection for localized disease
Chemotherapy for metastatic disease
Proton pump inhibitors Proton Pump Inhibitors Medications for decreasing acidity are used for peptic ulcer, gastroesophageal reflux disease (GERD), and many forms of gastritis. Some medications are used in regimens for treating Helicobacter... read more are the medications of choice (eg, omeprazole or esomeprazole 40 mg orally 2 times a day). The dose may be decreased gradually once symptoms resolve and acid output declines. A maintenance dose is needed; patients need to take these medications indefinitely unless they undergo surgery.
Octreotide injections, 100 to 500 mcg subcutaneously twice a day to 3 times a day, may also decrease gastric acid production and may be palliative in patients who are not responding well to proton pump inhibitors. A long-acting form of octreotide (20 to 30 mg IM once a month) can be used.
Surgical removal should be attempted in patients without apparent metastases because of the high risk of underlying cancer. At surgery, duodenotomy and intraoperative endoscopic transillumination or ultrasonography help localize tumors.
Surgical cure is possible in 20% of patients if the gastrinoma is not part of a multiple endocrine neoplasia syndrome.
In patients with metastatic disease, streptozocin in combination with 5-fluorouracil or doxorubicin is the preferred chemotherapy for islet cell tumors. The combination may reduce tumor mass (in 50 to 60%) and serum gastrin levels and is a useful adjunct to omeprazole.
Newer chemotherapies under investigation for insulinoma include temozolomide-based regimens, everolimus, or sunitinib. Patients with metastatic disease are not cured by chemotherapy.
Prognosis for Gastrinoma
Five- and 10-year survival are > 90% when an isolated tumor is removed surgically vs 43% at 5 years and 25% at 10 years with incomplete removal.
Most gastrinomas manifest with peptic ulcer symptoms, but some patients present with diarrhea.
About half of patients have multiple gastrinomas and about half have multiple endocrine neoplasia syndrome; half of gastrinomas are malignant.
Serum gastrin levels are usually diagnostic, but patients with borderline elevated levels may need a secretin provocative test.
Tumors can usually be localized with CT, somatostatin receptor scintigraphy, or positron emission tomography (PET).
Acid secretion is suppressed with a proton pump inhibitor and sometimes also with octreotide, pending surgical removal.
Drugs Mentioned In This Article
|ChiRhoStim , SecreFlo
|Prilosec, Prilosec OTC
|Nexium, Nexium 24HR, Nexium 24HR Clear Minis
|Bynfezia, Mycapssa, Sandostatin, Sandostatin LAR
|Adrucil, Carac, Efudex, Fluoroplex, Tolak
|Adriamycin, Adriamycin PFS, Adriamycin RDF, Rubex
|Afinitor , Afinitor DISPERZ, Zortress