Zollinger‑Ellison‑like syndrome (gastrin‑producing pancreatic NET) - Symptoms, Causes, Treatment & Prevention

Overview

Zollinger‑Ellison‑like syndrome (ZES‑like) refers to a group of rare neuroendocrine tumors (NETs) of the pancreas that secrete excess gastrin, the hormone that stimulates stomach acid production. The condition mimics classic Zollinger‑Ellison syndrome—named after the physicians who first described the disease—but occurs without the genetic mutations typical of the inherited form (MEN‑1). In practice, “Zollinger‑Ellison‑like syndrome” is used to describe sporadic gastrin‑producing pancreatic NETs that behave similarly to the classic disease.

• Who it affects: Adults, usually between 30 and 60 years of age. Slight male predominance (≈55% male).
• Prevalence: Gastrinoma (gastrin‑producing NET) incidence is about 0.5–2 cases per million per year. Sporadic (non‑MEN‑1) gastrinomas represent roughly 80 % of all gastrinomas, making ZES‑like syndrome exceedingly rare ^[1][2].

Symptoms

Because the tumor secretes gastrin, patients develop hyper‑acidic stomach conditions that lead to a broad spectrum of gastrointestinal and systemic symptoms.

• Peptic ulcer disease (PUD): Multiple, recurrent ulcers in the duodenum, jejunum, or even the stomach; ulcers can be refractory to standard therapy.
• Severe abdominal pain: Burning or gnawing pain that may improve with meals (due to acid buffering) or worsen with fasting.
• Diarrhea: Stools are often watery, foul‑smelling, and may be fatty (steatorrhea) because excess acid inactivates pancreatic enzymes.
• Gastro‑esophageal reflux disease (GERD): Heartburn, regurgitation, and esophagitis secondary to high acid load.
• Nausea & vomiting: May occur after meals or with ulcer perforation.
• Weight loss: Resulting from malabsorption, chronic diarrhea, and reduced appetite.
• Fatigue & iron‑deficiency anemia: Chronic blood loss from ulcers or impaired iron absorption in an acidic environment.
• Osteoporosis: Long‑term hyperacidity can impair calcium absorption.
• Skin flushing or itching: Rare, but may accompany larger NETs that secrete other vasoactive substances.

Symptoms often develop gradually, and many patients are misdiagnosed with common ulcer disease before the underlying gastrinoma is discovered.

Causes and Risk Factors

Unlike hereditary Zollinger‑Ellison syndrome (associated with MEN‑1 gene mutations), ZES‑like syndrome typically arises sporadically. The exact cause of sporadic gastrinomas is unknown, but several factors increase risk:

• Genetic mutations: Somatic mutations in the MEN1 gene, ATRX, DAXX, or the VHL gene have been identified in pancreatic NETs, including gastrinomas ^[3].
• Age & sex: Most cases present after age 30; slight male predominance.
• Chronic atrophic gastritis: May cause hypergastrinemia, but does not usually lead to gastrinoma; however, it can mask the diagnosis.
• Family history of NETs: While not hereditary MEN‑1, a family history may suggest an underlying predisposition.

Diagnosis

Diagnosis is a stepwise process that combines clinical suspicion, laboratory testing, imaging, and sometimes functional studies.

1. Laboratory Tests

• Fasting serum gastrin: Levels > 1,000 pg/mL (normal < 100 pg/mL) are highly suggestive. Levels ≥ 10× upper limit of normal with a gastric pH < 2 confirm hypergastrinemia due to a gastrinoma ^[4].
• Secretin stimulation test: In gastrinomas, serum gastrin paradoxically rises after an IV bolus of secretin (≥ 120 pg/mL increase), helping differentiate from other causes of hypergastrinemia.
• Other labs: CBC (to assess anemia), serum calcium, vitamin D, and iron studies.

2. Endoscopic Evaluation

• Upper endoscopy (EGD): Identifies ulcer locations, assesses severity, and obtains biopsies to rule out malignancy.

3. Imaging Studies

• Multiphasic CT abdomen/pelvis: First‑line for tumor localization; detects lesions > 5 mm.
• Magnetic resonance imaging (MRI) with diffusion‑weighted imaging: Improves detection of small pancreatic NETs.
• Somatostatin receptor scintigraphy (Octreoscan) or ^68Ga‑DOTATATE PET/CT: Highly sensitive for gastrinomas because > 80 % express somatostatin receptors ^[5].
• EUS (endoscopic ultrasound): Excellent for locating lesions < 1 cm in the pancreas or duodenum.

4. Staging

After tumor localization, staging follows AJCC 8th edition criteria (T, N, M) and assesses for metastasis, most commonly to the liver.

Treatment Options

Management aims to control acid hypersecretion, remove or control the tumor, and monitor for recurrence.

Acid‑Suppressive Therapy

• High‑dose proton pump inhibitors (PPIs): Omeprazole 40–80 mg daily or equivalent; often required lifelong to prevent ulcer complications.
• H2‑receptor antagonists: Used as adjuncts or if PPIs are not tolerated.

Surgical Management

• Curative resection: Enucleation or pancreaticoduodenectomy (Whipple) for localized tumors.
• Debulking surgery: For metastatic disease when > 90 % tumor burden can be removed, improving symptom control.

Medical Oncology

• Somatostatin analogues (SSA): Octreotide or lanreotide bind somatostatin receptors, reducing gastrin secretion and tumor growth. First‑line for unresectable or metastatic disease.
• Targeted therapy: Everolimus (mTOR inhibitor) or sunitinib (tyrosine‑kinase inhibitor) are FDA‑approved for advanced pancreatic NETs.
• Peptide receptor radionuclide therapy (PRRT): ^177Lu‑DOTATATE delivers targeted radiation; shows high response rates in somatostatin‑receptor positive gastrinomas.
• Chemotherapy: Typically reserved for high‑grade neuroendocrine carcinomas; regimens include streptozocin + 5‑FU or CAPTEM (capecitabine + temozolomide).

Liver‑Directed Therapies (for metastases)

• Radiofrequency ablation (RFA)
• Transarterial chemo‑embolization (TACE)
• Selective internal radiation therapy (SIRT)

Lifestyle & Supportive Care

• Small, frequent meals to reduce acid spikes.
• Avoid NSAIDs, aspirin, and alcohol—agents that aggravate ulcer disease.
• Maintain adequate calcium and vitamin D intake; bone density monitoring.
• Psychosocial support: NETs can cause anxiety; counseling or support groups are beneficial.

Living with Zollinger‑Ellison‑like Syndrome (gastrin‑producing pancreatic NET)

Long‑term success depends on adherence to medication, regular follow‑up, and lifestyle adjustments.

Daily Management Tips

1. Take PPIs exactly as prescribed. Missing doses can precipitate ulcer bleeding.
2. Set medication reminders. Many patients benefit from phone alarms or pillboxes.
3. Monitor symptoms. Keep a diary of pain, stool frequency, and any bleeding signs.
4. Nutrition: Choose low‑fat, bland foods; incorporate complex carbs and lean protein.
5. Hydration: Replace fluids lost to diarrhea; oral rehydration solutions can help.
6. Regular labs. Quarterly gastrin levels and annual CBC, calcium, vitamin D, and bone density.
7. Imaging surveillance. Typically every 6–12 months with MRI or PET/CT per oncologist’s recommendation.
8. Vaccinations. Hepatitis B, flu, and COVID‑19 vaccines are important, especially if receiving immunosuppressive therapy.

Psychosocial Strategies

• Join NET‑focused support groups (e.g., NET Patient Foundation).
• Consider cognitive‑behavioral therapy for anxiety related to chronic disease.
• Practice stress‑reduction techniques such as mindfulness or gentle yoga.

Prevention

Because most cases are sporadic, primary prevention is limited. However, risk reduction strategies include:

• Avoid chronic use of medications that increase stomach acidity (e.g., chronic H2 antagonists leading to rebound hypergastrinemia).
• Promptly treat Helicobacter pylori infection—while it does not cause gastrinomas, it can exacerbate ulcer disease.
• Maintain regular health check‑ups if you have a family history of NETs or MEN‑1.

Complications

If untreated or inadequately controlled, ZES‑like syndrome can lead to serious health problems.

• Peptic ulcer perforation – emergent surgery may be required.
• Upper gastrointestinal bleeding – can be life‑threatening.
• Malabsorption & severe diarrhea – leading to electrolyte disturbances and weight loss.
• Liver metastases – the most common site of spread; may cause hepatic dysfunction.
• Bone demineralization – osteoporosis & fractures due to chronic acid‑induced calcium loss.
• Neuroendocrine tumor progression – high‑grade transformation can occur, necessitating more aggressive chemotherapy.

When to Seek Emergency Care

---

Sources:
[1] Mayo Clinic. “Zollinger‑Ellison syndrome.” Link.
[2] National Cancer Institute. “Neuroendocrine Tumors.” Link.
[3] NCCN Guidelines Version 2.2024. “Neuroendocrine and Pancreatic Tumors.”
[4] Cleveland Clinic. “Gastrinoma (Zollinger‑Ellison).” Link.
[5] WHO Classification of Tumours of the Digestive System, 5th Edition, 2023.