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Gastric Carcinoid

Sabiston

Gastric Neuroendocrine Tumors (Gastric NETs)

Overview:

  • Definition: Rare malignancies arising from neuroendocrine precursor cells.
  • Common GI sites: Small intestine, rectum, appendix, and increasingly the stomach (8% of tumors).
  • Etiology: The rise in gastric NETs is linked to improved surveillance and widespread PPI use.
  • Symptoms: Typically non-functioning, rarely cause carcinoid syndrome.

Subtypes of Gastric NETs:

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  • Type I:
    • Most common (70%-80% of cases).
    • Associated with chronic achlorhydria, atrophic gastritis, pernicious anemia, or prolonged PPI use.
    • Multiple small tumors confined to mucosa/submucosa.
    • Prognosis: Relatively benign with favorable outcomes.
  • Type II:
    • Associated with hypergastrinemia from gastrinomas and ZES.
    • Similar to Type I with multiple small tumors.
    • Prognosis: Good, with long-term survival of 70%-90%, but with a higher risk of metastasis (5%-35%).
  • Type III:
    • Sporadic lesions without associated conditions or hypergastrinemia.
    • Present as large solitary lesions.
    • Prognosis: More aggressive with a 5-year survival of 25%-30% and higher rates of metastasis.
  • Type IV (Neuroendocrine carcinoma):
    • Very aggressive with widespread metastatic disease at presentation.
    • Rarely curable; surgery only for symptom control (e.g., bleeding, perforation, obstruction).

Diagnosis:

  • Esophagogastroduodenoscopy (EGD) with biopsy.
  • Endoscopic Ultrasound (EUS): Assesses depth of invasion.
  • CT or MRI: Evaluates metastatic disease.
  • Chromogranin A: Often elevated, useful as a biomarker.

Treatment:

  • Localized tumors: Complete removal.
    • Small pedunculated lesions: Endoscopic removal.
    • Larger lesions (>1 cm): May require wedge resection or partial gastrectomy.
  • Type I NETs:
    • Consider antrectomy to reduce gastrin secretion.
    • Total gastrectomy may be required for multiple lesions.
  • Type II NETs: Resect gastrinomas if possible.
  • Type III NETs: Oncologic resection with lymphadenectomy.
  • Recurrent/metastatic disease:
    • Somatostatin analogues or chemotherapy to reduce disease burden and treat carcinoid syndrome.