This page was reviewed under our medical and editorial policy by
Toufic Kachaamy, MD, Chief of Medicine, City of Hope Phoenix
This page was updated on May 26, 2023.
Gastrinomas are a rare form of pancreatic neuroendocrine tumor (NET) that begins in the neuroendocrine cells of the pancreas. Pancreatic NETs are uncommon, accounting for fewer than 2 percent of all pancreatic cancers, according to the American Cancer Society.
Neuroendocrine cells are hormone-producing cells, and pancreatic NETs may or may not produce hormones. Tumors that produce hormones and cause symptoms are called functioning NETs, and tumors that don’t release hormones or don’t release enough hormones to cause noticeable symptoms are called nonfunctioning NETs. Nonfunctioning NETs tend to grow much bigger than functioning NETs before they’re diagnosed due to their lack of symptoms.
Different types of neuroendocrine cells release different types of hormones. For example, gastrinomas release gastrin. Functioning tumors that originate in gastrin-producing cells excrete too much gastrin into the bloodstream.
When working correctly, gastrin is released in small amounts after you eat, but gastrinomas may trigger a condition called Zollinger-Ellison syndrome, in which the stomach produces excess acid, ulcers, bleeding and severe reflux. Gastrinomas may be in the pancreas or the duodenum (the first part of the small intestine), and be either malignant (cancerous) or benign (noncancerous).
Zollinger-Ellison syndrome (ZES) occurs when gastrinomas cause the stomach to produce too much acid. Gastrinomas generally occur in the small intestine or pancreas, and it’s possible for patients to develop multiple gastrinomas, which may potentially become cancerous. ZES is a rare condition, only affecting 0.5 to 3 people out of a million each year, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).
Symptoms of Zollinger-Ellison syndrome may include:
However, these symptoms may also be caused by other health conditions, such as peptic ulcer disease, so patients should consider talking to a doctor if they notice unexplained changes to their body.
ZES develops slightly more often in men than in women and is diagnosed most often in patients 20 to 50 years of age. Approximately 20 percent of patients diagnosed with Zollinger-Ellison syndrome also have multiple endocrine neoplasia type 1 (MEN1), a rare genetic condition, according to NIDDK. If a patient has a family history of MEN1, this may increase their chances of being diagnosed with Zollinger-Ellison syndrome.
Medications to help reduce stomach acid production (called proton pump inhibitors, or PPIs) and tumor removal surgery may be appropriate options for treating ZES.
When too much gastrin causes Zollinger-Ellison syndrome, the amount of acid in your stomach remains at higher-than-normal levels. Too much acid may cause stomach ulcers that cause the following symptoms:
When severe, stomach ulcers may bleed. Even a small amount of bleeding may result in a condition called anemia, in which not enough red blood cells are present. Anemia may cause tiredness and shortness of breath. With severe bleeding, your stool may look tarry and black. Severe bleeding may also become life-threatening.
If excess stomach acid affects your small intestine, it may cause damage to the cells of its lining. It may also cause digestive enzymes present in the small intestine to deteriorate before they’re able to digest food, resulting in diarrhea and loss of weight. It’s possible you also may develop gastroesophageal reflux disease (GERD), a condition in which the contents of your stomach travel up to the esophagus, causing irritation and damage to the esophageal lining.
While the uncontrolled division and reproduction of gastrin-producing cells contributes to the occurrence of gastrinomas, research to identify their exact cause is ongoing.
However, it’s known that an inherited genetic condition called multiple endocrine neoplasia type 1 (MEN1) syndrome causes 25 percent to 30 percent of all gastrinomas, according to The National Pancreas Foundation. People with MEN1 develop tumors in their endocrine glands and/or duodenum that produce excess hormones.
If you have the following risk factors, the odds of developing gastrinomas increase but aren’t guaranteed.
If you have stomach or duodenum ulcers that don’t go away with treatment, your doctor may conduct a physical examination, ask about your symptoms and gather your health history.
Next, you may undergo a fasting blood test to check for elevated gastrin levels. Prior to the test, it’s necessary to stop using acid-reducing medications. If your results are 10 times above normal levels, Zollinger-Ellison syndrome is likely.
Your doctor may also conduct a secretin stimulated blood test. This test determines whether the level of gastrin in your blood increases after you’re given an intravenous (IV) infusion of a hormone called secretin. High levels of gastrin along with an increased level of stomach acid may indicate Zollinger-Ellison syndrome.
Additionally, your doctor may perform an upper gastrointestinal (GI) endoscopy to view your esophagus, stomach and duodenum. Your care team may recommend this to investigate ulcers and signs of irritation using an endoscope, a thin lighted tube with a camera on the end. This may be combined with an endoscopic ultrasound to examine the pancreas, where some gastrinomas may occur.
If a diagnosis is confirmed, it’s important to find out where the tumor(s) are located, which may be tough because gastrinomas are usually very small in size.
To locate them, you may need one or more of the following scans.
Computed tomography (CT) scan: X-ray images are created, sometimes with the help of a contrast dye injected into your body.
Magnetic resonance imaging (MRI): Images of your body’s organs and tissues are taken from multiple angles with the use of magnets; sometimes contrast dye is used.
Endoscopic ultrasound (EUS): An endoscope is used to take an ultrasound of your pancreas. The tool has a small ultrasound probe that may be used to identify gastrinomas.
Angiogram: A catheter is woven through your arteries and contrast dye is injected so that the area of interest shows up clearly on X-ray images.
Somatostatin receptor scintigraphy: This scan is conducted with a gamma camera. A radioactive compound (radiotracer) is injected into your bloodstream to make gastrinoma cells more apparent on the scan.
Gallium Ga-68 DOTATATE PET/CT: This is an integrated PET/CT scan that is very sensitive to neuroendocrine tumors like gastrinomas. It may help with diagnosis and provide localization.
Treatment for gastrinomas varies depending on the size and location of your tumor, but it may include surgery to remove the gastrinoma, medications to reduce stomach acid production and/or medications to reduce the size of your tumor, or chemotherapy:
Medication: Proton pump inhibitors (PPIs) work by preventing acid from being pumped into the stomach, reducing symptoms and allowing your ulcers to heal. PPIs include:
Surgery: The only cure for Zollinger-Ellison syndrome is complete removal of the gastrinoma before it metastasizes to other areas.
Surgery for gastrinomas in the duodenum: If your tumor is located in the small intestine, a procedure called a duodenectomy will likely be performed. During the surgery, an incision is made into your abdomen, and the tumor is removed.
Surgery for gastrinomas in the pancreas: The type of surgery you have depends on the location of the tumor in the pancreas. If it’s in the head (the widest part of the pancreas), the entire tumor may be removed. If the tumor is located closer to the pancreatic duct, your surgery may entail removal of the pancreas’ head or tail, the gallbladder, duodenum and part of the bile duct. This surgery is called a pancreatectomy: total, central, distal or Whipple procedure. In the latter, part of the stomach may also be removed. If the gastrinoma has spread to your liver, doctors may also remove this tumor and possibly a portion of the liver.
Chemotherapy: If gastrinomas cannot be removed by surgery, chemotherapy drugs such as the following may be administered.
Minimally invasive procedures: The care team may use minimally invasive procedures such as radiofrequency ablation or radioembolization in combination or as alternatives to other treatments to help reduce the tumor burden.
Clinical trials: Check with your care team if you’re interested in joining a clinical trial to see whether one is available and whether you’re a good candidate.
Among people who have surgery to remove a gastrinoma that hasn’t spread, the five-year survival rate is 95 percent, and the 10-year survival rate is 90 percent, according to Cancer Research UK. In cases where the gastrinoma has spread to the liver, the five-year survival rate is 50 percent, and the 10-year survival rate is 30 percent.