A gastrinoma is a tumor usually in the pancreas or duodenum (the first segment of the small intestine) that produces excessive levels of the hormone gastrin, which stimulates the stomach to secrete acid and enzymes, causing peptic ulcers.
- These tumors arise from cells in the pancreas that produce gastrin.
- Symptoms are similar to those caused by peptic ulcers, including pain and bleeding.
- Diagnosis includes blood and imaging tests.
- The survival rate is high if the tumor is completely removed.
- Treatment includes drugs to reduce acid in the stomach and sometimes surgery and chemotherapy.
Gastrinomas are a type of pancreatic endocrine tumor. Most people with gastrinomas have several tumors clustered in or near the pancreas or the duodenum. About half of the tumors are cancerous. Sometimes a gastrinoma occurs as part of multiple endocrine neoplasia, a hereditary disorder in which tumors arise from the cells of various endocrine glands, such as the insulin-producing cells of the pancreas.
Symptoms of Gastrinoma
The excess gastrin secreted by the gastrinoma causes the stomach to produce far too much acid. This overproduction of acid can results in Zollinger-Ellison syndrome. In Zollinger-Ellison syndrome, a person has symptoms of aggressive peptic ulcers (such as pain or bleeding) in the stomach, duodenum, and elsewhere in the intestine. However, as many as 25% of people with Zollinger-Ellison syndrome may not have an ulcer when the diagnosis is made. Rupture, bleeding, and obstruction of the intestine can occur and can be life threatening. For more than half of the people with a gastrinoma, symptoms are no worse than those experienced by people with ordinary peptic ulcer disease. In 25 to 40% of people, diarrhea resulting from the excess acid production is the first symptom.
Diagnosis of Gastrinoma
- Blood tests
- Imaging tests
A doctor suspects a gastrinoma when a person has frequent peptic ulcers or several peptic ulcers that do not respond to the usual ulcer treatments. Blood tests to detect abnormally high levels of gastrin are the most reliable diagnostic tests.
Once blood tests diagnose gastrinoma, doctors try to locate the tumor using several imaging techniques, such as computed tomography (CT) of the abdomen, scintigraphy (a type of radionuclide scanning), endoscopic ultrasonography, positron emission tomography (PET) scans, and arteriography (an x-ray taken after a radiopaque dye is injected into an artery). These tumors may be difficult to find, however, because usually they are small.
Prognosis of Gastrinoma
If the tumor is completely surgically removed, people have a greater than 90% chance of surviving 5 to 10 years. If the tumor is not completely removed, people have a 43% chance of surviving 5 years and a 25% chance of surviving 10 years.
Treatment of Gastrinoma
- Methods to reduce levels of stomach acid
- Sometimes surgical removal
- Sometimes chemotherapy
High doses of proton pump inhibitors, which are acid-reducing drugs (see Table: Drug Treatment of Stomach Acid) may be effective for reducing acid levels and relieving symptoms temporarily. If these drugs are not effective enough, injections of octreotide may help. If there is only one tumor and the person does not have multiple endocrine neoplasia, doctors usually do surgery to remove the gastrinoma. In such cases, surgical removal cures about 20% of people.
If these treatments do not work, an operation to remove the stomach completely (total gastrectomy) may be necessary. This operation does not remove the tumor, but the gastrin can no longer create ulcers after the acid-producing stomach is removed. If the stomach is removed, daily iron and calcium supplements taken by mouth and monthly injections of vitamin B12 are needed, because absorption of these nutrients is impaired when stomach juices that prepare these nutrients for absorption are no longer available.
If cancerous tumors have spread to other parts of the body, chemotherapy may help reduce the number of tumor cells and the levels of gastrin in the blood. However, such therapy does not cure the cancer, which is ultimately fatal.
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