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Zollinger‑Ellison Syndrome (a Type of Neuroendocrine Tumor)

Overview

Zollinger‑Ellison syndrome (ZES) is a rare disorder caused by gastrin‑secreting neuroendocrine tumors (NETs)—most often located in the pancreas or duodenum. These tumors, called gastrinomas, produce excessive amounts of the hormone gastrin, which overstimulates the stomach’s acid‑producing cells. The resulting hyperacidity leads to severe peptic ulcers, diarrhea, and malabsorption.

Who it affects: ZES can occur at any age but is most commonly diagnosed in adults aged 30‑60. Both men and women are affected, with a slight male predominance (≈55 %). About 20‑25 % of cases are hereditary, occurring as part of the hereditary cancer syndrome **multiple endocrine neoplasia type 1 (MEN‑1)**.

Prevalence: Sporadic ZES is estimated at 0.5–2 cases per million people per year. When MEN‑1 is included, the overall prevalence rises to roughly 1 in 100,000 [1][2].

Symptoms

Symptoms stem from excess gastric acid and the tumor’s mass effect. Not all patients experience every symptom.

Gastro‑intestinal manifestations

• Refractory peptic ulcers – often multiple, located beyond the duodenum (including the jejunum), and resistant to standard ulcer therapy.
• Abdominal pain – cramping or burning pain that may improve after meals (due to acid neutralization) but can also worsen with ulcer complications.
• Chronic diarrhea – watery, often nighttime, caused by acid‑induced injury to the intestinal mucosa and malabsorption of fats.
• Steatorrhea – fatty, foul‑smelling stools reflecting fat malabsorption.
• Nausea & vomiting – may be severe if ulcer perforation occurs.

Systemic and metabolic signs

• Weight loss – due to malabsorption, chronic diarrhea, and reduced appetite.
• Fatigue & anemia – from chronic blood loss in ulcers or iron malabsorption.
• Electrolyte disturbances – low potassium or magnesium from persistent diarrhea.

Signs related to tumor location

• Pancreatic mass – may cause a palpable abdominal lump or back pain.
• Duodenal mass – can lead to obstructive jaundice if it compresses the bile duct.

Causes and Risk Factors

ZES results from the uncontrolled growth of gastrin‑producing neuroendocrine cells. The underlying mechanisms differ between sporadic and hereditary forms.

Genetic causes

• MEN‑1 syndrome – caused by mutations in the MEN1 tumor suppressor gene. Approximately 20‑25 % of ZES patients have MEN‑1.
• Familial gastrinoma syndrome – rare, autosomal dominant inheritance not linked to MEN‑1.

Sporadic gastrinomas

• Arise without a known inherited mutation; most commonly located in the “gastrinoma triangle” (duodenum, pancreas, and peripancreatic soft tissue).

Risk factors

• Family history of MEN‑1 or gastrinoma.
• Age – incidence peaks in the fourth to sixth decades.
• Chronic atrophic gastritis – can increase gastrin levels but does not directly cause gastrinomas; however, it may exacerbate ulcer disease.

Diagnosis

Diagnosing ZES involves confirming hypergastrinemia, ruling out other causes of high gastrin, and locating the gastrinoma.

Laboratory tests

• Fasting serum gastrin level – Levels > 1000 pg/mL are highly suggestive; values 2–3 × upper limit of normal with gastric pH < 2 also support the diagnosis.
• Secretin stimulation test – In ZES, gastrin paradoxically rises > 120 pg/mL after IV secretin; this test helps differentiate ZES from other hypergastrinemic states.
• Stool studies – Fecal fat quantification if steatorrhea is suspected.

Imaging to locate the tumor

• Multiphasic contrast CT scan – First‑line for abdominal imaging; detects masses > 1 cm.
• Magnetic resonance imaging (MRI) with gadolinium – Useful for liver metastases and small duodenal lesions.
• Endoscopic ultrasound (EUS) – High sensitivity for pancreatic and duodenal gastrinomas ≤ 1 cm.
• Somatostatin receptor scintigraphy (Octreoscan) or Ga‑68 DOTATATE PET/CT – Gold standard for detecting neuroendocrine tumors and metastatic disease.

Endoscopic assessment

• Upper endoscopy (EGD) – Identifies ulcer disease, biopsies for H. pylori, and sometimes visualizes duodenal masses.

Genetic testing

If MEN‑1 is suspected (family history, other endocrine tumors), testing for MEN1 mutations is recommended.

Treatment Options

Management combines acid control, tumor-directed therapy, and surveillance.

Acid‑suppression therapy (first line)

• High‑dose proton pump inhibitors (PPIs) – Omeprazole 80‑120 mg daily or equivalent; they are the most effective way to control ulcer disease and diarrhea.
• Histamine‑2 receptor antagonists – Less potent; may be added if PPIs alone are insufficient.

Surgical treatment

• Curative resection – Enucleation or pancreaticoduodenectomy for localized gastrinomas; cure rates up to 60 % for tumors < 2 cm without metastasis.
• Debulking surgery – Reduces tumor burden when metastases are present; improves symptom control.

Medical therapies for unresectable or metastatic disease

• Somatostatin analogues (octreotide, lanreotide) – Inhibit gastrin release, control symptoms, and may stabilize tumor growth.
• Targeted therapy – Everolimus (mTOR inhibitor) approved for advanced pancreatic NETs; can slow progression.
• Peptide‑receptor radionuclide therapy (PRRT) – ^177Lu‑DOTATATE delivers radiation directly to somatostatin‑receptor‑positive tumors; improves progression‑free survival.
• Chemotherapy – Generally limited to high‑grade neuroendocrine carcinomas; regimens include streptozocin‑5‑FU or temozolomide‑capecitabine.

Liver‑directed therapies (for hepatic metastases)

• Radiofrequency ablation, trans‑arterial chemo‑embolization (TACE), or selective internal radiation therapy (SIRT).

Lifestyle and supportive measures

• Small, frequent meals; avoid foods that trigger ulcer pain (spicy, acidic).
• Vitamin and mineral supplementation (especially calcium, vitamin D, iron, and B‑12) due to malabsorption.
• Hydration and electrolyte replacement for chronic diarrhea.

Living with Zollinger‑Ellison Syndrome (type of neuroendocrine tumor)

Long‑term management focuses on symptom control, monitoring for tumor progression, and maintaining nutritional health.

Daily medication adherence

• Take PPIs exactly as prescribed—missing doses can quickly precipitate ulcer pain.
• Schedule regular injections or oral dosing of somatostatin analogues if prescribed.

Nutritional strategies

• Consume a diet low in fat to lessen steatorrhea; incorporate medium‑chain triglyceride (MCT) oils which are easier to absorb.
• Use pancreatic enzyme supplements if instructed by a gastroenterologist.
• Track weight and BMI; report any unintentional loss > 5 % of body weight to your physician.

Monitoring schedule

• Serum gastrin and chromogranin A every 6–12 months.
• Imaging (CT/MRI or Ga‑68 DOTATATE PET) annually, or sooner if symptoms change.
• Endoscopic surveillance every 1–2 years to assess ulcer healing.

Psychosocial support

• Connect with patient advocacy groups (e.g., Neuroendocrine Tumor Research Foundation).
• Consider counseling or support groups to address anxiety or depression related to chronic illness.

Prevention

Because ZES is largely driven by genetic mutations, primary prevention is limited. However, certain steps may reduce disease burden or complications:

• For families with MEN‑1, pursue genetic counseling and early screening for gastrinomas and other endocrine tumors.
• Avoid long‑term use of NSAIDs or corticosteroids, which can worsen ulcer formation.
• Screen and eradicate Helicobacter pylori infection—while it does not cause ZES, it can compound ulcer disease.

Complications

If untreated or inadequately controlled, ZES can lead to serious health problems:

• Perforated peptic ulcer – life‑threatening intra‑abdominal infection.
• Bleeding ulcer – may require transfusion or endoscopic hemostasis.
• Gastrointestinal obstruction – from ulcer scarring or tumor mass.
• Severe malnutrition – due to chronic diarrhea and fat malabsorption.
• Liver metastases – occur in up to 60 % of patients; may cause liver dysfunction.
• Secondary cancers – MEN‑1 patients have increased risk of pancreatic, pituitary, and parathyroid tumors.

When to Seek Emergency Care

References

1. Mayo Clinic. “Zollinger‑Ellison syndrome.” Updated 2023. https://www.mayoclinic.org/diseases‑conditions/zollinger‑ellison‑syndrome
2. National Institutes of Health – Genetics Home Reference. “Multiple endocrine neoplasia type 1.” 2022. https://ghr.nlm.nih.gov/condition/multiple-endocrine-neoplasia-type-1
3. Cleveland Clinic. “Zollinger‑Ellison Syndrome: Diagnosis & Treatment.” 2024. https://my.clevelandclinic.org/health/diseases/17267-zollinger-ellison-syndrome
4. World Health Organization. “Neuroendocrine Tumors.” 2023. https://www.who.int/news-room/fact-sheets/detail/neuroendocrine-tumours
5. EFGH (European Neuroendocrine Tumor Society). “Guidelines for Management of Gastrinomas.” 2022. https://www.enets.org/guidelines

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