Gastrinomas
Gastrinomas are rare, slow-growing tumors that secrete high levels of the hormone gastrin, primarily arising in the duodenum, pancreas, or pancreatic lymph nodes. They are associated with Zollinger-Ellison syndrome, characterized by excessive stomach acid leading to ulcers and gastrointestinal issues. Men are at a higher risk of developing gastrinomas, particularly those with the genetic disorder multiple endocrine neoplasia type 1 (MEN1), where a significant percentage of patients develop pancreatic gastrinomas. Symptoms typically include persistent abdominal pain, chronic diarrhea, heartburn, nausea, vomiting, weight loss, and gastrointestinal bleeding. Diagnosis involves measuring blood gastrin levels and performing imaging studies to locate the tumor. Treatment focuses on managing acid production and may involve surgical removal when localized, along with proton pump inhibitors and chemotherapy for advanced cases. The prognosis varies: favorable outcomes are seen in patients with isolated tumors, while those with metastasis, especially to the liver, typically face more serious challenges. Regular monitoring and lifelong management are often required for affected individuals.
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Subject Terms
Gastrinomas
ALSO KNOWN AS: Gastrin-secreting tumors; G cell tumor; Zollinger-Ellison syndrome; islet cell tumor, ulcerogenic
RELATED CONDITIONS: Peptic ulcers, gastroesophageal reflux disease (GERD), multiple neoplasia type 1 (MEN1), liver cancer
DEFINITION: Gastrinomas are slow-growing tumors that secrete large quantities of the peptide hormone gastrin. Gastrinomas most often arise in the wall of the duodenum, the pancreas, or the pancreatic lymph nodes.
Risk factors: Gastrinomas arise spontaneously or in association with the rare genetic disorder multiple endocrine neoplasia type 1 (MEN1). Men have double the risk of developing gastrinoma relative to women. Between 40 and 60 percent of all MEN1 patients will develop pancreatic gastrinomas. In 2024, the National Pancreas Foundation reported that approximately 25 to 30 percent of gastrinomas are caused by MEN1.
Etiology and the disease process: The large amount of gastrin produced by gastrinomas causes the stomach to produce massive quantities of acid. The acid causes ulcers to form in the stomach and duodenum, a condition known as Zollinger-Ellison syndrome, and can irritate and inflame the esophagus. The acid also produces water and ion imbalances in the small intestine, resulting in diarrhea. More than 60 percent of gastrinomas are malignant, usually metastasizing to nearby and the liver.
Incidence: Gastrinomas are exceedingly rare tumors, occurring in 0.5 to three people per million. Gastrinomas are usually diagnosed when people are between twenty and fifty but can occur at any age.
Symptoms: The most common symptom of gastrinoma is persistent upper abdominal pain due to severe or recurring ulcers. Chronic diarrhea is the second most frequent symptom, followed by heartburn. Other symptoms include nausea, vomiting, weight loss, and ulcer-related gastrointestinal bleeding.
Screening and diagnosis: An initial diagnosis is made by measuring gastrin levels in the blood and acid output by the stomach after an overnight fast. Elevated levels of both are a presumptive diagnosis of gastrinoma. Somatostatin receptor scintigraphy is the preferred imaging technology to locate the tumor and check for metastasis. Other imaging tests include multiphasic computed tomography (CT) scan, magnetic resonance imaging (MRI), nuclear medicine imaging, somatostatin receptor scintigraphy with a combined single photon emission computed tomography and computed tomography (SPECT/CT), and gallium-somatostatin analog combined positron emission tomography and computed tomography PET/CT imaging. An X-ray of blood vessels while the gastronoma is producing gastrin may also be beneficial.
Treatment and therapy: Treatment of gastrinoma involves controlling acid production and surgical removal of tumors. Surgery to remove the gastrinoma is most beneficial, but it is only possible when the disease is localized. Proton pump inhibitor medications are the most potent agents for blocking acid secretion. Chemotherapy with streptomycin, 5-fluorouracil, and doxorubicin can shrink tumors and control metastasis-associated symptoms but does not prolong survival time.
Prognosis, prevention, and outcomes: The five-year survival rate for patients with isolated, operable tumors is between 62 and 92 percent, and surgery is curative in 20 to 25 percent of cases. For patients with liver metastasis or numerous diffuse tumors, the five-year survival rate is between 20 and 75 percent, depending on the type of metastases. Tumors that have spread to the liver are usually inoperable and are the main cause of death in gastrinoma patients. Tumor recurrence is monitored by regular screening of fasting gastrin levels. Lifelong treatment with medications to control acid production is often necessary.
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