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Gastric neuroendocrine tumours

Section: UGI Sub-section: Gastric Curriculum: Curriculum, page 96

  • Arise from Enterochromaffin-like Cells
    • Located in Gastric Fundus or Body
    • Neural crest origin
    • Base of Crypts of Lieberkühn
  • Rare
    • <1% of gastric neoplasms, 8% of all GIT NETs

Type 1 Gastric NETS

  • 70-80% of Gastric NETs
  • Older pts, F > M 3:1
  • Associated Chronic Atrophic Gastritis
    • Achlorhydria and Vit B12 malabsorption (Pernicious Anaemia)
      • Decreased acid, pH, leads to increased gastrin
      • Causes hyperplasia of ECL cells
    • NB: CAG very common in elderly, only 1% develop NETs
  • In fundus/body, frequently multicentric
    • Mostly small, Rarely > 2cm
  • Small lesions almost always benign
    • 1cm predominantly benign, <10% invasion
    • If invasive, behave well, low risk mets (5% to LNs, 2% distant)
  • Very rare to die from this

Type 2 Gastric NETS

  • 6-8% of gastric NETS
  • Associated with MEN1 and Gastrinoma causing ZES
  • F=M, age 45-50
  • NB: ECL hyperplasia in 80% of MEN1 ZES
    • 5-30% of these develop gastric NETs
    • Hyperplasia, dysplasia, neoplasia sequence
  • Hypergastrinaemia and MEN1 gene abnormality seemingly needed for gastric NET formation
    • Very rare to have gastric NETs in ZES that are sporadic and not caused by ZES
    • Very rare to have gastric NETs in MEN1 patients that don’t have ZES
  • Located body and fundus
    • Mostly multiple and small, occasionally larger
  • Malignant potential intermediate
    • 90% non-invasive
    • But if invasive, 30% LN mets, 10-20% distant mets
    • NB: Potential for other tumours related to MEN 1 to have caused the metastases
  • Overall prognosis usually depends on other MEN 1 related tumours
    • Prognosis for type 2 NETs is favourable

Type 3 Gastric NETS

  • 15-20% of gastric NETs
  • Sporadic, no association to hypergastrinaemia
    • Non-atrophic gastric mucosa
  • M > F 3:1, Age 50yrs
  • Usually solitary
  • Often large 70% > 1cm, mean 3.2cm
  • Much more aggressive than Type 1 and 2
    • Many already disseminated by diagnosis
    • LN metastases in 71%
    • Liver metastases 69%
    • Total survival 50% at 5yrs
      • If distant metastases – 10% 5yr survival
  • Mostly well differentiated, often G2 (Ki67 > 2%)
  • Atypical carcinoid syndrome in 5-10%
    • The flushes may be patchy, sharply demarcated, serpiginous, and cherry red; they are also intensely pruritic. Diarrhea or cardiac lesions are unusual. The tumors that cause this variant syndrome secrete histamine
    • Tumour histamine release – breakdown product MelmAA in urine as tumour marker
    • Itching, cutaneous oedema, bronchospasm, salivary gland swelling, lacrimation
  • Very few have serotonin release
    • Urinary 5-HIAA not appropriate tumour marker

Diagnosis

  • Most found incidentally
    • On scope for anaemia or abdo symptoms
    • Can bleed or have gastric outlet obstruction if large
  • Hx
    • ? Chronic atrophic gastritis,
    • ? MEN1 related malignancies (3Ps)
  • Bloods
    • Gastrin, MEN1 screen
  • Gastroscopy
    • Biopsy of lesion and 2 x antral, fundus, body
    • Look for ECL Hyperplasia, Atrophic Gastritis
  • EUS for
    • Types 1 & 2 > 1cm
  • All type 3
  • Staging – CT CAP
  • Octreotide scan can be considered in well differentiated tumours

Management

  • Type 1 – Chronic Atrophic Gastritis
    • Follow yearly if < 1cm

    • 1 cm with no invasion – EMR

    • If larger or invasive, surgical excision
    • Malignancy – partial/total gastrectomy with lymphadenectomy
  • Type 2 – Gastrinoma/Zollinger Ellison
    • Need to remove source of gastrin (gastrinoma) and the NET
    • Open exposure, both duo and pancreas seen via duodenotomy - 80% distal pancreatectomy most often performed
    • Local excision of the gastric NET also unless large
    • Larger get Gastric resection and lymphadenectomy
  • Type 3 Sporadic
    • Risk of malignancy even if small
    • Most require gastric resection with lymphadenectomy

    • 2cm consider gastrectomy

    • If mets, tumour debulking may alleviate symptoms
    • Hepatic mets – resection/Hepatic A embolisation/TACE/RFA
    • Octreotide for symptomatic palliation

2023 ENET Management guidelines Type 1

  • <1cm observe
  • 1-2cm gray zone

  • 2cm resect

Type 2 “Type II gNETs are the rarest type of gNET (5% of cases). They arise in the context of hypergastrinaemia associated with ZES which may occur in patients with MEN-I. Treatment of patients with type II gNETs strictly depends on the management of the MEN-I syndrome.”

Type 3

  • All require resection
  • Option based on size, grade and depth of invasion

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