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Zollinger‑Ellison Gastric Tumor (Zollinger‑Ellison Syndrome)

Overview

Zollinger‑Ellison syndrome (ZES) is a rare disorder caused by a gastrin‑secreting neuroendocrine tumor (often called a gastrinoma) that most commonly arises in the pancreas or duodenum but can also develop in the stomach, hence the term “gastric tumor.” The excess gastrin stimulates the stomach lining to produce large amounts of gastric acid, leading to severe peptic ulcer disease, diarrhea, and malabsorption.

• Incidence: Approximately 1–3 cases per million people per year worldwide [1].
• Age: Median age at diagnosis is 45–55 years, but cases occur in children and the elderly.
• Gender: Slight male predominance (about 55 % male) [2].
• Associated conditions: About 25 % of patients have multiple endocrine neoplasia type 1 (MEN 1), an inherited disorder that predisposes to pancreatic, pituitary and parathyroid tumors [3].

Symptoms

The hallmark of ZES is hypersecretion of gastric acid. Symptoms can be intermittent early on and become more severe as the tumor grows.

Gastro‑intestinal symptoms

• Recurrent abdominal pain: Often epigastric, worsened by meals.
• Peptic ulcers: Multiple ulcers in the duodenum, jejunum, or even the distal small bowel; they tend to be larger and resistant to standard ulcer therapy.
• Heartburn / gastro‑esophageal reflux disease (GERD): Due to excessive acid spilling into the esophagus.
• Diarrhea: Occurs in 30‑50 % of patients; can be watery or steatorrhic (fatty) because acid inactivates pancreatic enzymes.
• Nausea and vomiting: May accompany ulcer perforation or obstruction.
• Weight loss: From malabsorption, chronic diarrhea, and reduced oral intake due to pain.

Systemic / extra‑intestinal symptoms

• Fatigue and anemia: Chronic blood loss from ulcers.
• Osteoporosis: Long‑term acid hypersecretion can impair calcium absorption.
• Kidney stones: Hypercalciuria secondary to altered calcium metabolism.
• Signs of MEN 1: Hyperparathyroidism (bone pain, kidney stones), pituitary adenoma (headaches, visual changes), or other pancreatic neuroendocrine tumors.

Causes and Risk Factors

ZES results from a gastrinoma, a type of pancreatic neuroendocrine tumor that secretes gastrin.

• Genetic mutations:
  • MEN 1 gene mutations (on chromosome 11q13) – account for ~25 % of cases.
  • Rare sporadic somatic mutations in the RET or VHL genes.
• Familial inheritance: Autosomal dominant transmission in MEN 1 families.
• Age and sex: Slight male predominance; risk rises after age 40.
• Environmental factors: No strong links to smoking, alcohol, or diet, unlike common duodenal ulcers.

Diagnosis

Because symptoms overlap with common ulcer disease, a high index of suspicion is essential, especially when ulcers are refractory to standard therapy or when they occur beyond the duodenum.

Laboratory tests

• Fasting serum gastrin level: > 1000 pg/mL (normal < 100 pg/mL) is highly suggestive, especially when accompanied by low gastric pH < 2.
• Secretin stimulation test: An increase in gastrin > 120 pg/mL after IV secretin is diagnostic in equivocal cases [4].
• Chromogranin A (CgA): Elevated in many neuroendocrine tumors; useful for monitoring.
• Other labs: CBC (anemia), electrolytes (to assess dehydration), calcium and parathyroid hormone if MEN 1 is suspected.

Imaging studies

• Upper endoscopy (EGD): Visualizes ulcers, allows biopsy to rule out malignancy.
• Endoscopic ultrasound (EUS): Highly sensitive for detecting small gastrinomas (< 1 cm).
• Multiphasic contrast CT or MRI of the abdomen: Identifies primary tumor and liver metastases.
• Somatostatin receptor scintigraphy (Octreoscan) or ^68Ga‑DOTATATE PET/CT: Gold standard for locating neuroendocrine tumors that express somatostatin receptors [5].

Histopathology

When surgical removal is performed, tissue is examined for:

• Neuroendocrine cell markers (chromogranin A, synaptophysin).
• Ki‑67 proliferation index – determines tumor grade (G1‑G3).

Treatment Options

Management focuses on controlling acid hypersecretion, removing or reducing tumor burden, and monitoring for recurrence.

Medical therapy – acid control

• Proton pump inhibitors (PPIs): High‑dose omeprazole, esomeprazole, or pantoprazole are first‑line. Doses often exceed conventional ulcer doses (e.g., omeprazole 60‑120 mg daily) and must be titrated to keep gastric pH > 4 [6].
• Histamine‑2 receptor antagonists (H2RAs): Used when PPIs are contraindicated, but less effective for severe ZES.
• Somatostatin analogues (octreotide, lanreotide): Reduce gastrin release and may shrink tumors, especially in metastatic disease.

Surgical management

• Curative resection: Enucleation or pancreaticoduodenectomy (Whipple) for localized gastrinomas.
• Debulking surgery: For metastatic disease, removal of > 90 % of tumor burden can improve symptom control.
• Liver-directed therapies: Radiofrequency ablation, embolization, or hepatic resection for liver metastases.

Targeted and systemic therapies

• Everolimus or sunitinib: Oral agents approved for advanced pancreatic neuroendocrine tumors; can stabilize disease.
• Peptide receptor radionuclide therapy (PRRT) with ^177Lu‑DOTATATE: Delivers targeted radiation to somatostatin‑receptor‑positive tumors, improving progression‑free survival [7].
• Chemotherapy: Reserved for high‑grade (G3) neuroendocrine carcinomas; regimens include streptozocin‑5‑FU or temozolomide‑capecitabine.

Lifestyle and supportive measures

• Small, frequent meals to reduce acid load.
• Avoidance of NSAIDs, aspirin, and alcohol, which aggravate ulcer formation.
• Calcium and vitamin D supplementation if long‑term PPI use is required (to protect bone health).
• Regular monitoring of serum gastrin, CgA, and imaging every 6–12 months.

Living with Zollinger‑Ellison Gastric Tumor

Long‑term management blends medication adherence, monitoring, and lifestyle adjustments.

Medication adherence

• Take PPIs exactly as prescribed; missing doses can cause rebound hyperacidity.
• Carry a rescue dose (e.g., an extra PPI tablet) for breakthrough symptoms.
• Inform all healthcare providers that you are on high‑dose PPIs—some procedures (e.g., certain surgeries) require acid suppression.

Nutrition

• Eat low‑fat, low‑spice meals; focus on lean protein, whole grains, and cooked vegetables.
• Limit caffeine and carbonated drinks, which can stimulate acid secretion.
• Consider a dietitian’s guidance if malabsorption leads to weight loss.

Monitoring & follow‑up

• Every 3‑6 months: CBC, electrolytes, calcium, vitamin D, and gastrin level.
• Annual imaging (CT/MRI or Ga‑68 PET) to detect recurrence or metastasis.
• Women of child‑bearing age should discuss pregnancy planning; high‑dose PPIs are generally safe, but tumor surveillance is essential.

Psychosocial support

• Join patient support groups (e.g., NET Patient Foundation) for shared experiences.
• Seek counseling if chronic illness leads to anxiety or depression.

Prevention

Because most gastrinomas are sporadic, primary prevention is limited. However, certain actions can lower risk or catch disease early:

• Family screening: First‑degree relatives of MEN 1 patients should undergo genetic counseling and periodic gastrin testing.
• Prompt evaluation of refractory ulcers: Early endoscopy and gastrin measurement can diagnose ZES before complications develop.
• Healthy gut practices: Avoid chronic NSAID use and smoking, which increase ulcer risk and may unmask symptoms earlier.

Complications

If untreated or poorly controlled, ZES can lead to serious health issues:

• Perforated peptic ulcer: Acute abdomen requiring emergency surgery.
• Gastrointestinal bleeding: May cause anemia or hemodynamic instability.
• Malabsorption and nutritional deficiencies: Fat‑soluble vitamin (A, D, E, K) deficiencies, leading to bone disease and coagulopathy.
• Metastatic disease: Liver, lymph nodes, or bone spread in up to 60 % of patients at diagnosis.
• Refractory diarrhea: Can cause electrolyte disturbances (hypokalemia, metabolic acidosis).
• Secondary infections: Long‑term high‑dose PPIs are associated with increased risk of Clostridioides difficile infection.

When to Seek Emergency Care

References

1. National Institute of Diabetes and Digestive and Kidney Diseases. “Zollinger‑Ellison Syndrome.” NIH, 2022.
2. World Health Organization. “Neuroendocrine Tumors of the Digestive System.” WHO Classification, 2023.
3. Marino J, et al. “MEN‑1 and Gastrinomas.” Cleveland Clinic Journal of Medicine, 2021.
4. Gibril F, et al. “Secretin Stimulation Test in the Diagnosis of Zollinger‑Ellison Syndrome.” Gastroenterology, 2020.
5. Holt J, et al. “Somatostatin Receptor Imaging for Neuroendocrine Tumors.” Journal of Nuclear Medicine, 2022.
6. Mayo Clinic. “Proton Pump Inhibitors: Uses and Side Effects.” 2023.
7. Strosberg J, et al. “^177Lu‑DOTATATE for Mid‑gut Neuroendocrine Tumors.” New England Journal of Medicine, 2021.

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