Zollinger‑Ellison Syndrome (Gastrinoma) – MEN1 Association

Overview

Zollinger‑Ellison syndrome (ZES) is a rare disorder in which one or more gastrin‑producing tumors (gastrinomas) develop, most often in the pancreas or duodenum. These tumors secrete excessive amounts of the hormone gastrin, leading to hyperacidity in the stomach. The resulting acid overload damages the lining of the gastrointestinal (GI) tract and causes severe peptic ulcer disease.

When ZES occurs as part of multiple endocrine neoplasia type 1 (MEN‑1)—an inherited cancer‑predisposition syndrome—the risk of gastrinomas and other endocrine tumors (parathyroid, pituitary, and pancreatic neuroendocrine tumors) is markedly increased.

• Prevalence of sporadic ZES: approximately 0.5–2 cases per million people per year.^[1]
• MEN‑1 prevalence: 2–4 per 100,000 individuals, with gastrinomas present in 20–30 % of MEN‑1 patients.^[2]
• Both men and women are affected; onset typically occurs in the 3rd‑5th decade of life, but MEN‑1–related ZES can present earlier, sometimes in adolescence.^[3]

Symptoms

The hallmark of ZES is **acid hypersecretion**, which manifests as a cluster of GI symptoms. In MEN‑1 patients, symptoms may be more variable because multiple endocrine tumors can coexist.

• Refractory Peptic Ulcers – ulcers that do not heal with standard therapy, often located in the duodenum, jejunum, or even the distal duodenum and beyond.
• Abdominal Pain – burning or cramping pain that worsens after meals.
• Diarrhea – watery, sometimes fatty stools caused by acid inactivation of pancreatic enzymes.
• Steatorrhea – foul‑smelling, greasy stools due to malabsorption of fat.
• Heartburn / GERD – chronic reflux from excess gastric acid.
• Nausea & Vomiting – especially after large meals.
• Weight Loss – secondary to malabsorption and reduced intake.
• Gastrointestinal Bleeding – melena or hematemesis from ulcer erosion.
• Osteopenia/Osteoporosis – long‑standing hyperacidity can impair calcium absorption.
• MEN‑1‑specific manifestations – hyperparathyroidism (hypercalcemia, kidney stones), pituitary tumors (headaches, visual changes), and other pancreatic neuroendocrine tumors (gastric carcinoids, insulinoma).

Causes and Risk Factors

Primary cause

ZES results from **neoplastic gastrin‑secreting cells** (gastrinomas). These are classified as pancreatic neuroendocrine tumors (PNETs) when located in the pancreas, or as duodenal neuroendocrine tumors when in the duodenum.

Genetic link – MEN‑1

• MEN‑1 Gene Mutation – a tumor‑suppressor gene on chromosome 11q13; loss‑of‑function mutations lead to unchecked cell growth in endocrine tissues.^[4]
• Inheritance – autosomal‑dominant with 50 % chance of transmission to offspring.
• Penetrance – >95 % of carriers develop at least one MEN‑1‑related tumor by age 50.

Other risk factors

• Family history of MEN‑1 or sporadic gastrinomas.
• Radiation exposure to the abdomen (rare, but reported).
• Chronic atrophic gastritis – may be a background factor for sporadic gastrinomas, though the link is weak.

Diagnosis

Diagnosis requires a combination of biochemical, imaging, and sometimes endoscopic studies.

Biochemical testing

• Fasting serum gastrin level – values > 5× the upper limit of normal (typically > 1000 pg/mL) in the presence of gastric acid hypersecretion strongly suggest ZES.^[5]
• Secretin stimulation test – paradoxical rise in gastrin after IV secretin; a rise ≥ 120 pg/mL is diagnostic.
• Gastric pH measurement – pH < 2 confirms hyperacidity.
• In MEN‑1 patients, simultaneous testing for calcium, PTH, prolactin, and IGF‑1 may be performed to screen for other endocrine tumors.

Imaging studies

• Contrast‑enhanced CT or MRI – first‑line for locating pancreatic or duodenal masses.
• Somatostatin receptor scintigraphy (Octreoscan) or ^68Ga‑DOTATATE PET/CT – highly sensitive for neuroendocrine tumors, especially small or metastatic lesions.^[6]
• Endoscopic ultrasound (EUS) – excellent for detecting lesions < 2 cm, guiding fine‑needle aspiration.
• Upper endoscopy (EGD) – visualizes ulcers, assesses severity, and obtains biopsies to rule out Helicobacter pylori‑related ulcers.

Pathology

If a lesion is resected, histology shows nests of uniform, round cells with eosinophilic cytoplasm that stain positive for gastrin and chromogranin A.

Treatment Options

Therapy aims to (1) control acid production, (2) remove or reduce tumor burden, and (3) monitor/ treat other MEN‑1 manifestations.

Acid‑suppression medication

• Proton pump inhibitors (PPIs) – e.g., omeprazole 60–120 mg daily (or higher in divided doses). PPIs are the mainstay; they rapidly normalize gastric pH and heal ulcers.^[7]
• H2‑receptor antagonists – used when PPIs are contraindicated or as adjuncts.
• Long‑term high‑dose PPI therapy may increase risk of Vitamin B12 deficiency, hypomagnesemia, and bone loss—monitor labs regularly.

Surgical management

• Curative resection – Preferred for solitary, resectable gastrinomas (especially pancreatic head or duodenal lesions < 2 cm).
• Enucleation – removal of the tumor alone, preserving pancreatic tissue.
• Pancreaticoduodenectomy (Whipple procedure) – reserved for multiple or large duodenal/pancreatic lesions.
• In MEN‑1 patients, disease is often multifocal; complete surgical cure is less common, and the goal shifts to tumor debulking and symptom control.

Medical therapies for tumor control

• Somatostatin analogues (octreotide, lanreotide) – inhibit gastrin release and can shrink neuroendocrine tumors; especially useful in MEN‑1 where surgery is limited.
• Targeted therapies – everolimus or sunitinib for progressive, unresectable pancreatic neuroendocrine tumors.^[8]
• Peptide receptor radionuclide therapy (PRRT) – ^177Lu‑DOTATATE for tumors expressing somatostatin receptors.
• Chemotherapy – rarely needed; reserved for high‑grade neuroendocrine carcinoma.

Lifestyle and supportive measures

• Avoid NSAIDs, aspirin, and smoking – these increase ulcer risk.
• Eat small, frequent meals; limit very acidic foods (citrus, tomato products) if tolerated.
• Calcium and vitamin D supplementation if on long‑term PPIs.
• Regular bone‑density testing (DEXA) due to osteoporosis risk.

Living with Zollinger‑Ellison Syndrome (gastrinoma) – MEN‑1 Association

Monitoring schedule

• Serum gastrin & gastric pH every 6–12 months.
• Annual cross‑sectional imaging (CT/MRI) or ^68Ga‑DOTATATE PET to detect new lesions.
• Quarterly endocrine panel for calcium, PTH, prolactin, IGF‑1 to catch other MEN‑1 tumors early.
• Endoscopic surveillance every 1–2 years if ulcers persist.

Practical daily tips

1. Medication adherence – take PPIs 30 minutes before breakfast and dinner; set phone reminders.
2. Stay hydrated – high gastric acid can cause fluid loss via diarrhea.
3. Nutrition – focus on high‑protein, low‑fat meals; consider pancreatic enzyme supplements if steatorrhea persists.
4. Stress management – stress can exacerbate ulcer pain; practice relaxation techniques.
5. Support network – join MEN‑1 patient groups (e.g., International MEN Consortium) for shared experiences.
6. Genetic counseling – all MEN‑1 patients should discuss family planning and cascade testing with relatives.

Prevention

Because gastrinomas are largely **genetically driven** in MEN‑1, primary prevention is limited. However, the following steps can reduce secondary complications:

• Screen individuals with a known MEN‑1 mutation from age 5–10 with annual calcium/PTH testing; early detection of hyperparathyroidism lowers ulcer risk.
• Eradicate Helicobacter pylori if present – it can aggravate ulcer formation.
• Avoid chronic use of ulcer‑inducing drugs (NSAIDs, corticosteroids) unless protective PPIs are co‑prescribed.
• Maintain a healthy bone‑mineral status (adequate calcium, vitamin D, weight‑bearing exercise).

Complications

• Refractory or perforated peptic ulcers – can lead to peritonitis, sepsis.
• Gastrointestinal bleeding – may require endoscopic or surgical intervention.
• Malabsorption & Nutritional deficiencies – fat‑soluble vitamins (A, D, E, K) loss, anemia.
• Osteoporosis – chronic acid suppression and malabsorption of calcium.
• Metastatic disease – gastrinomas can spread to liver, lymph nodes, or bone; metastatic ZES worsens prognosis.
• MEN‑1 related tumors – primary hyperparathyroidism, pituitary adenomas, other pancreatic neuroendocrine tumors; each carries its own morbidity.
• Renal stones – hypercalcemia from hyperparathyroidism.

When to Seek Emergency Care

References

1. Mayo Clinic. “Zollinger‑Ellison syndrome.” Accessed April 2024.
2. National Cancer Institute. “Multiple endocrine neoplasia type 1 (MEN1).” 2023.
3. Cleveland Clinic. “Zollinger‑Ellison Syndrome Overview.” 2024.
4. Marini, F. et al. “MEN1 gene mutations and clinical phenotype.” Endocrine Reviews, 2022.
5. American College of Gastroenterology. “Guidelines for the Diagnosis and Management of ZES.” 2023.
6. Strosberg, J. et al. “^68Ga‑DOTATATE PET/CT in Neuroendocrine Tumors.” J Clin Oncol, 2021.
7. NIH. “Proton Pump Inhibitors: Long‑Term Use Risks.” 2022.
8. Therasse, P. et al. “Targeted Therapy for Pancreatic Neuroendocrine Tumors.” NEJM, 2020.