What are gastrinomas (Gastrin-producing tumors)?

From the Guidelines

Gastrinomas are rare neuroendocrine tumors that secrete excessive amounts of the hormone gastrin, leading to a condition called Zollinger-Ellison syndrome, characterized by severe gastroduodenal ulcer symptoms, diarrhea, and elevated gastrin levels, as noted in the study by 1. These tumors typically develop in the pancreas or duodenum (first part of the small intestine) and cause the stomach to produce too much acid, leading to multiple, often treatment-resistant peptic ulcers, severe abdominal pain, and diarrhea.

Key Characteristics of Gastrinomas

• They are rare neuroendocrine tumors
• They secrete excessive amounts of the hormone gastrin
• They typically develop in the pancreas or duodenum
• They cause the stomach to produce too much acid
• They lead to multiple, often treatment-resistant peptic ulcers, severe abdominal pain, and diarrhea About 60-70% of gastrinomas are malignant with potential to spread to nearby lymph nodes and the liver, as discussed in the context of neuroendocrine tumors by 1.

Diagnosis and Treatment

• Diagnosis involves measuring fasting gastrin levels, secretin stimulation tests, and imaging studies like CT scans, MRIs, or endoscopic ultrasound, as outlined in the study by 1
• Treatment typically includes proton pump inhibitors (PPIs) such as omeprazole (40-60 mg twice daily) or pantoprazole (40 mg twice daily) to control acid production
• Surgical removal is recommended when the tumor is localized and hasn't metastasized, with approaches including duodenotomy, intraoperative ultrasound, and local resection or enucleation of tumors, as described by 1
• For metastatic disease, additional treatments may include chemotherapy, targeted therapies, or peptide receptor radionuclide therapy Regular monitoring is essential as these tumors can be part of Multiple Endocrine Neoplasia type 1 (MEN1), a hereditary condition affecting multiple endocrine glands.

Important Considerations

• The concurrent use of proton pump inhibitors can elevate serum gastrin levels and confound diagnosis, as noted by 1
• Gastrin levels must be measured after the patient is off proton pump inhibitor therapy for at least 1 week
• A combination of fasting serum gastrin level greater than 10 times elevated and a gastric pH less than 2 is diagnostic of a gastrinoma, as stated in the study by 1

From the Research

Definition and Characteristics of Gastrinomas

• Gastrinomas are tumors that secrete excessive amounts of gastrin, a hormone that stimulates the production of gastric acid [(2,3)].
• These tumors are typically found in the pancreas or upper duodenum and are associated with Zollinger-Ellison syndrome, a condition characterized by severe peptic ulcer disease and diarrhea [(2,3)].
• Gastrinomas are usually present within the "gastrinoma triangle," which is composed of the porta hepatis, duodenal sweep, and pancreatic head 2.

Types and Treatment of Gastrinomas

• Gastrinomas can occur in a familial or sporadic form, with patients in the familial setting of Multiple Endocrine Neoplasia type 1 (MEN-1) being less likely to be cured by surgery 3.
• Surgery is currently used to remove duodenal and pancreatic gastrinomas, with duodenotomy improving tumor detection and cure rates 3.
• The treatment of gastrinomas often involves the use of proton pump inhibitors to reduce gastric acid secretion and alleviate symptoms [(4,5,6)].

Diagnosis and Localization of Gastrinomas

• The diagnosis of gastrinomas often involves imaging studies, such as In-111 pentetreotide scans, to localize the tumor 2.
• The use of somatostatin analogues, such as pentetreotide, can help identify neuroendocrine tumors, including gastrinomas 2.
• Operative resection and immunohistochemical staining can confirm the diagnosis of a gastrinoma 2.