Zollinger-Ellison Syndrome and Gastrinomas

What is Zollinger-Ellison Syndrome?

Zollinger-Ellison syndrome is a rare disorder characterized by the development of a tumor called a Gastrinoma found in the pancreas and/or duodenum. Gastrinomas secrete excessive levels of gastrin, a hormone that stimulates the production of acid by the stomach. Normally, the body releases small amounts of gastrin after eating, which triggers the stomach to make gastric acid which helps break down food and liquid in the stomach. The extra acid causes peptic ulcers to form in the duodenum and elsewhere in the upper intestine. Although anyone can get Zollinger-Ellison syndrome, the disease is more common among men 30 to 50 years old.

The prevalence of the disease occurs in approximately 10 per million of the population. Also, a child who has a parent with MEN1 is also at increased risk for Zollinger-Ellison syndrome. Medical researchers are still studying the exact cause of Zollinger-Ellison syndrome. About 25 to 30 percent of Gastrinomas are caused by an inherited genetic disorder called multiple endocrine neoplasia type 1 (MEN1).1 MEN1 causes hormone-releasing tumors in the endocrine glands and the duodenum. Symptoms of MEN1 include increased hormone levels in the blood, kidney stones, diabetes, muscle weakness, weakened bones, and fractures.

Symptoms

Zollinger-Ellison syndrome signs and symptoms are similar to those of peptic ulcers. A dull or burning pain felt anywhere between the navel and mid-chest is the most common symptom of a peptic ulcer. Other symptoms of Zollinger-Ellison syndrome include:

• diarrhea
• mild to severe abdominal pain
• steatorrhea (increased amounts of fat in the stools)
• bloating
• burping
• nausea
• vomiting
• weight loss
• poor appetite

Some people with Zollinger-Ellison syndrome have only diarrhea, with no other symptoms. Others develop gastroesophageal reflux (GER), which occurs when stomach contents flow back up into the esophagus.

How are gastrinomas diagnosed?

A diagnosis of Gastrinoma should be considered in a patient with peptic ulcers that recur frequently and are resistant to treatment. A medical professional may suggest a biochemical study called the Secretin Stimulated blood test to check for an elevated gastrin level after an infusion of secretin. Secretin is a hormone that causes gastrinomas to release more gastrin. A technician or nurse places an intravenous (IV) needle in a vein in the arm to give an infusion of secretin. A medical professional may suspect Zollinger-Ellison syndrome if blood drawn after the infusion shows an elevated gastrin level. Once a diagnosis is made, localizing the tumor is important. Most gastrinomas are small lesions and therefore, localizing the tumor may be difficult. Some of the tests that are performed to localize the tumor include a CT scan, octreotide scan MRI, and an endoscopic ultrasound. An experienced surgeon will detect these tumors at surgery even when they are not visible on preoperative imaging tests.

How are gastrinomas treated?

Treatment of choice for Gastrinoma is to remove the surgically where possible. Peptic ulcers must be aggressively treated and controlled before surgery. The type of surgery for gastrinomas depends on the location of the tumor. Since these tumors may frequently occur at more than one spot in the pancreas and the surrounding tissues more than one procedure may be required.

The following operative procedures may be utilized to treat gastrinomas:

• Enucleation: Many small gastrinomas in the pancreas may be treated by enucleation alone. This is a procedure of choice for patients who have small tumors (less than 1cm) where the tumor is located on the surface of the pancreas.
• Resection of the pancreas: in patients with large tumors a distal pancreatectomy or a Whipple operation may be indicated depending on where the tumor is located in the pancreas.
• Duodenal exploration: Gastrinomas often occur in the wall of the duodenum (first part of the intestine) and therefore opening the duodenum and carefully feeling it to remove any tumors in this area is important.
• Lymph nodes: In some patients, the tumor may be located in the lymph glands outside the pancreas therefore careful palpation and removal of these glands is important at the time of surgery In some affected individuals with aggressively invasive Gastrinoma, recommended treatment may include the use of certain anticancer drugs (chemotherapy) to help reduce tumor mass and blood gastrin levels. Genetic counseling may be of benefit to affected individuals and their families. Other treatment for this disease is symptomatic and supportive.