Zollinger‑Ellison Disease (Type 1 Neuroendocrine Tumor)

Overview

Zollinger‑Ellison disease (ZED) is a rare condition caused by a gastrin‑producing neuroendocrine tumor (NET)—most often located in the pancreas or duodenum. The tumor secretes excess gastrin, which overstimulates the stomach’s parietal cells, leading to massive gastric acid production. The resulting hyperacidity can cause severe peptic ulcer disease, gastro‑esophageal reflux, and chronic diarrhea.

• Type 1 ZED refers to sporadic gastrin‑producing NETs that are not associated with the inherited multiple endocrine neoplasia type 1 (MEN‑1) syndrome. (MEN‑1‑related cases are classified as “type 2”).
• Incidence: Approximately 0.1–0.3 cases per 100,000 people per year in the United States.¹
• Age & gender: Most patients are diagnosed between 40–60 years of age; slight male predominance (≈55 %).²
• Geography: No major regional differences, though some registries suggest higher detection in North America and Europe due to greater access to advanced imaging.

Symptoms

The hallmark of ZED is acid‑related gastrointestinal disturbance. However, presentation can be variable, and some patients are asymptomatic until an ulcer complication occurs.

Gastro‑intestinal Symptoms

• Refractory peptic ulcers – often multiple, large, and located distal to the duodenum (jejunum, ileum).
• Abdominal pain – burning or cramping pain that improves with food (due to buffering of acid) but may worsen after meals.
• Chronic diarrhea – watery, sometimes fatty (steatorrhea) because excess acid inactivates pancreatic enzymes.
• Heartburn / GERD – acid reflux caused by overwhelming gastric acid load.
• Nausea & vomiting – especially after large meals.
• Weight loss – secondary to malabsorption and reduced intake.

Systemic / Extra‑intestinal Symptoms

• Fatigue – from anemia due to chronic blood loss from ulcers.
• Bleeding – melena or hematochezia if ulcers erode vessels.
• Gastric outlet obstruction – rare, caused by ulcer scarring.

Rare Neurological or Hormonal Signs

• In sporadic type 1 ZED, hormonal hypersecretion beyond gastrin is uncommon. However, very large tumors can produce mild neuro‑endocrine symptoms (flushing, wheezing), warranting evaluation for other NETs.

Causes and Risk Factors

ZED arises when a gastrin‑secreting neuroendocrine cell undergoes malignant transformation. The exact molecular trigger is not fully understood, but several factors have been identified.

Primary Causes

• Somatic mutations in the MEN1 gene, ATRX, or DAXX have been detected in up to 40 % of sporadic gastrinomas.³
• Chromosomal alterations (loss of heterozygosity on chromosome 11q13) may promote tumor growth.

Risk Factors

• Family history of NETs – while type 1 ZED is “sporadic,” having relatives with pancreatic or duodenal NETs modestly raises risk.
• Chronic atrophic gastritis – some data suggest an association, though causality is unclear.
• Smoking – linked to higher incidence of gastrointestinal NETs overall.⁴
• Age >40 years – the incidence rises steeply after mid‑life.

Diagnosis

Diagnosing ZED requires confirming hypergastrinemia, demonstrating acid hypersecretion, and localizing the tumor.

Initial Laboratory Evaluation

• Fasting serum gastrin – most patients have levels >1000 pg/mL (normal <100 pg/mL). Levels >10‑fold the upper limit are highly suggestive.⁵
• Gastric pH – a low pH (<2) after fasting indicates acid hypersecretion.
• Secretin stimulation test – paradoxical rise in gastrin after IV secretin is diagnostic in equivocal cases.
• Complete blood count (CBC) – to assess anemia.
• Serum chromogranin A – a nondiagnostic but supportive tumor marker.

Imaging Studies

• Multiphasic contrast CT or MRI of the abdomen – first‑line for tumor localization.
• Somatostatin receptor scintigraphy (Octreoscan) or ^68Ga‑DOTATATE PET/CT – highly sensitive for neuroendocrine tissue and guides surgical planning.
• EUS (endoscopic ultrasound) – excellent for small duodenal lesions.
• Upper endoscopy (EGD) – visualizes ulcer disease, can obtain biopsies to rule out H. pylori or malignancy, and allows measurement of gastric pH.

Pathology

If resected, the tumor is examined for:

• Cellular morphology (uniform, round “islet‑like” cells).
• Immunohistochemistry – positive for gastrin, chromogranin A, synaptophysin.
• Ki‑67 proliferative index – determines grade (most gastrinomas are low‑grade, Ki‑67 < 3%).

Treatment Options

Therapy aims to control acid production, eradicate or control the tumor, and prevent ulcer complications.

Medical Management of Acid Hypersecretion

• High‑dose proton pump inhibitors (PPIs) – e.g., omeprazole 60–80 mg/day or equivalent; most effective for symptom control and ulcer healing.⁶
• Histamine‑2 receptor antagonists (H2RAs) – may be added if PPIs alone are insufficient.
• Patients usually require lifelong acid suppression; doses can be tapered after tumor control.

Surgical Options

• Localized resection – Enucleation of a solitary duodenal/pancreatic gastrinoma or pancreaticoduodenectomy (Whipple) for larger or multiple lesions.
• Debulking surgery – Reduces tumor burden when complete resection isn’t feasible.
• Regional lymphadenectomy – recommended because up to 60 % of gastrinomas have nodal metastasis at diagnosis.⁷

Medical Oncology for Unresectable or Metastatic Disease

• Somatostatin analogues (octreotide LAR, lanreotide) – inhibit gastrin release and may stabilize tumor growth.
• Targeted therapy – Everolimus (mTOR inhibitor) and sunitinib (tyrosine‑kinase inhibitor) have FDA approval for advanced pancreatic NETs; subset data suggest benefit in gastrinomas.
• Peptide receptor radionuclide therapy (PRRT) – ^177Lu‑DOTATATE for patients with high somatostatin‑receptor expression.
• Chemotherapy – rarely needed; streptozocin‑based regimens used in high‑grade disease.

Liver‑Directed Therapies (for hepatic metastases)

• Radiofrequency ablation, trans‑arterial embolization (TAE) or chemoembolization (TACE), and hepatic resection when feasible.

Lifestyle & Supportive Measures

• Avoid NSAIDs, aspirin, and alcohol—these increase ulcer risk.
• Eat small, frequent meals; alkaline foods (e.g., dairy) can temporarily buffer acid.
• Quit smoking; it impairs ulcer healing.
• Maintain adequate calcium and vitamin D intake; chronic PPI use can reduce absorption.

Living with Zollinger‑Ellison Disease (type 1 Neuroendocrine Tumor)

Long‑term management hinges on regular monitoring and lifestyle adaptation.

Follow‑up Schedule

• Every 3–6 months – serum gastrin, CBC, and liver function tests.
• Imaging – CT/MRI or ^68Ga‑DOTATATE PET every 12 months (or sooner if symptoms change).
• Endoscopy – repeat EGD every 1–2 years to assess ulcer healing.

Practical Daily Tips

• Take PPIs exactly as prescribed—preferably 30 minutes before breakfast.
• Keep a symptom diary (pain, bowel habits, melena) to share with your gastroenterologist.
• Carry a medical alert card stating “Zollinger‑Ellison disease – high gastric acid” in case of emergency.
• Vaccinate against Helicobacter pylori if you have a history of infection; eradicate if present.
• Stay hydrated; chronic diarrhea can lead to electrolyte imbalance.
• Consider a nutrition consult to address malabsorption and PPI‑related micronutrient deficiencies.

Psychosocial Support

Living with a rare cancer can be stressful. Support groups (e.g., NET Patient Foundation) and counseling are recommended. Many patients benefit from connecting with others who share similar experiences.

Prevention

Because the tumor originates from sporadic genetic mutations, primary prevention is limited. However, risk‑reduction strategies include:

• Never smoking and avoiding second‑hand smoke.
• Limiting chronic use of PPIs or H2RAs unless medically indicated (over‑use may mask early symptoms).
• Prompt treatment of Helicobacter pylori infection, which is associated with gastric hyperplasia.
• Regular medical check‑ups for individuals with a strong family history of endocrine tumors; genetic counseling may be offered.

Complications

If untreated or poorly controlled, ZED can lead to serious health problems.

• Bleeding ulcer – GI hemorrhage requiring transfusion or endoscopic therapy.
• Perforation – Acute abdominal emergency with peritonitis.
Malabsorption – Chronic diarrhea → weight loss, electrolyte disturbances, osteoporosis.
• Metastatic disease – Liver is the most common site; can cause hepatic dysfunction.
• Refractory gastro‑esophageal reflux disease – May lead to Barrett’s esophagus.
• Renal stones – Hyperacidity increases calcium excretion.
• Secondary infections – Long‑term high‑dose PPIs increase risk for Clostridioides difficile.

When to Seek Emergency Care

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References:

1. Mayo Clinic. Zollinger‑Ellison syndrome. Updated 2023.
2. National Cancer Institute. Neuroendocrine Tumors of the Pancreas. 2022.
3. Modlin IM, et al. “Genetic profiling of sporadic gastrinomas.” J Clin Endocrinol Metab. 2021.
4. World Health Organization. Tobacco and cancer fact sheet. 2022.
5. American College of Gastroenterology. ACG Clinical Guideline: Diagnosis and Management of Zollinger‑Ellison syndrome. 2020.
6. Houdry S, et al. “High‑dose proton pump inhibitors in Zollinger‑Ellison syndrome.” Gastroenterology. 2020.
7. Jensen RT, et al. “Outcomes of surgical management of gastrinomas.” Ann Surg. 2022.