Zollinger-Ellison Syndrome - Causes, Symptoms, Diagnosis, and Treatment

Introduction:

Zollinger-Ellison syndrome is a condition in which one or more tumors are found in the pancreas or upper part of the small intestine. These tumors are called Gastrinomas. Gastrinomas cause excess production of hormones known as “Gastrin.” This hormone regulates the level of gastric acid in the stomach, which helps in the digestion of food. Excess levels of gastric acid cause rupture of the inner lining of the stomach leading to the formation of peptic ulcers.

Peptic ulcers are sores that are formed due to erosion of the inner lining of the stomach.

What Is Zollinger-Ellison Syndrome?

A condition is called a syndrome when a set of symptoms appear together and suggest the presence of a certain disease. Zollinger-Ellison syndrome is characterized by the development of one or more tumors called Gastrinomas. Gastrinomas develop on the duodenum or pancreas, which are both benign and malignant. These tumors cause excess production of gastric acid that leads to rupture of the inner lining of the stomach and cause peptic ulcers. Excess gastric acid causes diarrhea and other health problems like peptic ulcer disease and gastroesophageal reflux disease (GERD).

What Causes Zollinger-Ellison Syndrome?

Research studies are still being conducted to reach the etiology of the cause of Zollinger-Ellison syndrome. Zollinger-Ellison syndrome is caused by multiple tumors called “Gastrinoma.” Gastrinomas develop in the pancreas or duodenum. The pancreas produces digestive juices and gastrin that help in the digestion of food. It also produces other hormones, including insulin. Insulin helps in regulating blood glucose levels.

Gastrinomas are the tumor masses in the pancreas, leading to excess production of the digestive juice, gastrin. Due to its acidic nature, tumors often become malignant. This syndrome is also known to be associated with a hereditary genetic disorder known as multiple endocrine neoplasia 1 (MEN 1). MEN 1 also produces a few hormones that are responsible for the formation of gastrinomas in the duodenum.

Who Is at Risk of Zollinger-Ellison Syndrome?

It is more prevalent in men than in women. It is found in people between the ages of 30 and 40. A family history of multiple endocrine neoplasias predisposes a person to develop Zollinger-Ellison syndrome. Persons with MEN 1 condition are more likely to develop ZES.

What Are the Symptoms of Zollinger-Ellison Syndrome?

Gastrinomas produce excess gastrin, due to which the patient might develop gastroesophageal reflux disease. The symptoms of this syndrome might be similar to that of GERD and peptic ulcer disease.

• Diarrhea.

• Pain in the abdomen or belly.

• Heartburn.

• Loss of weight.

• Vomiting.

• Nausea.

• Breathlessness.

• Bleeding inside the digestive tract.

• Steatorrhea (bloody stool).

• Loss of appetite.

• Bloating.

Sometimes, diarrhea could be the only symptom without any other symptoms.

How Can Zollinger-Ellison Syndrome Be Diagnosed?

• Biochemical Study: This test is used to examine the gastric levels in the blood. This is also called secretin stimulated blood test. Secretin is a hormone that induces gastrinoma to produce more gastrin. Secretin is given to the patient via intravenous infusion and thereby checking for gastrin levels in the blood. If the blood tests show elevated gastrin after the infusion of secretin, the presence of gastrinoma is suspected.

• Stomach Acid Tests: This test is performed by inserting a tube into the stomach through the nose. Fluids from the stomach are collected to study the pH of the acids produced.

• Upper Gastrointestinal Endoscopy: This test is performed by inserting a tube called an endoscope into the stomach. This test allows looking at the lining of the stomach, peptic ulcers, and gastrinomas.

• Endoscopic Retrograde Cholangiopancreatography: This test is a combination of endoscopy and X-ray that allows looking at bile ducts and pancreatic ducts.

• Imaging Tests: Imaging tests are used to locate gastrinomas. This test helps in determining the size and location of gastrinomas. Imaging tests that are used to diagnose Zollinger-Ellison syndrome are:

• Magnetic resonance imaging (MRI)

• Computed tomography (CT)

• Radionuclide scanning

• Ultrasound endoscopy

• Angiography

• 68G Ga-Dotatate PET CT

What Is the Treatment for Zollinger-Ellison Syndrome?

• Surgery:

Surgery is the best treatment option when the gastrinomas are non-malignant. Surgeries that can be chosen depending on the diagnosis are as follows:

1. Enucleation: This surgery can be chosen when gastrinoma is small and located on the surface of the pancreas.

2. Resection of the Pancreas: When the tumor is large, Whipple operation- removal of the head of the pancreas is advised depending on the location of gastrinoma.

3. Duodenal Exploration: When the tumor is located on the wall of the duodenum, careful exploration and removal of the tumor can be performed.

4. Lymph Nodes: If the tumor has become metastatic and reached the lymph nodes, careful palpation of the lymph nodes and their removal during surgery is advised.

• Medications:

Patients with Zollinger-Ellison syndrome are best cured with the usage of proton pump inhibitors (PPIs). PPI’s reduce the levels of gastrin which reduces the symptoms and allows healing. PPIs have very few side effects and are hence commonly prescribed medication. Few patients may need to take PPIs forever. Long-term use of PPIs may cause headaches, stomach upset, and deficiency of Vit B12. Some patients have been prescribed H2 blockers that reduce gastrin production. H2 blockers that are widely prescribed are Ranitidine and Cimetidine. In the case of malignant or invasive gastrinomas, chemotherapy- the use of anticancer drugs is advised.

• Treatment of Invasive or Aggressive Gastrinoma:

When the tumor has spread to the liver, this treatment is best considered to alleviate the symptoms and expand the patient's life. This approach is also known as liver-directed therapy. Liver-directed therapy will not cure the disease but only help reduce the symptoms. Some of the liver-directed therapies are:

1. Transarterial Chemoembolization (TACE): It is a combination of chemotherapy and embolization. Embolization is the process of blocking blood flow to cancer, so the cancer cells die.

2. Radionuclide-Laden Spheres: This therapy uses tumor-targeting nanoscale and microscale carriers that selectively carry nucleotides to the tumor area, improving the outcome of cancer diagnosis and treatment.

3. Local Ablative Therapy: It is a minimally invasive procedure to destroy cancer cells either by surgery, radio ablation, or cryoablation.

• Cytotoxic Chemotherapy:

Though these medications have cured a lower number of patients with Zollinger-Ellison syndrome, they have shown a 70% reduction of the disease radiographically. Some of the medications are Temozolomide and Capecitabine. Due to its effectiveness, this treatment option is also considered neoadjuvant therapy.

• Targeted Therapy:

The food and drug administration (FDA) has approved the use of Everolimus and Sunitinib for advanced pancreatic neuroendocrine tumors.

• Somatostatin Analogues:

The Food and Drug Administration (FDA) has approved Peptide receptor radionuclide therapy (PRRT) for the treatment of neuroendocrine tumors. This therapy combines octreotide and a radioactive material which results in the formation of radiopeptide. This radiopeptide is then injected into the bloodstream for the treatment of tumors.

What Is the Prognosis of Zollinger-Ellison Syndrome?

Gastrinomas grow very slowly. Early detection and surgical removal of these tumors increase the life span of the patient.

Conclusion:

It is a rare digestive disorder that causes excess production of stomach acids. When left untreated, it can become life-threatening. Tumors grow very slowly, which gives time for proper treatment planning. People with hereditary tendencies are advised to undergo periodic checkups.