What are the symptoms and surgical management of neuroendocrine tumors (NETs)?

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Symptoms and Surgical Management of Neuroendocrine Tumors

Surgical resection is the primary and potentially curative treatment for localized neuroendocrine tumors, with the specific surgical approach determined by tumor size, location, functionality, and grade. 1

Symptoms of Neuroendocrine Tumors

Symptoms of NETs vary based on tumor functionality, location, and hormone production:

Functional NETs (Hormone-Producing)

  • Insulinomas: Hypoglycemia, confusion, sweating, palpitations, and symptoms related to insulin excess 1
  • Gastrinomas: Peptic ulcer disease, abdominal pain, diarrhea, and gastroesophageal reflux due to excessive gastrin production 1
  • Glucagonomas: Recent-onset diabetes, cachexia, necrolytic erythematous skin rash 1
  • VIPomas: Watery diarrhea, electrolyte imbalances, dehydration (WDHA syndrome) 1

Non-functional NETs

  • Often asymptomatic until advanced stages
  • May present with:
    • Mass effect symptoms (abdominal pain, jaundice, bowel obstruction)
    • Weight loss
    • Fatigue
    • Nonspecific abdominal discomfort 1

Preoperative Management

Before surgical intervention:

  1. Control hormonal symptoms:

    • Insulinomas: Stabilize glucose with diet and/or diazoxide; use octreotide with caution as it can worsen hypoglycemia 1
    • Gastrinomas: Proton pump inhibitors to control gastric acid hypersecretion 1
    • VIPomas and glucagonomas: Octreotide to control symptoms 1
    • Consider total parenteral nutrition for patients with severe weight loss (glucagonoma) 1

  2. Preoperative vaccination:

    • Trivalent vaccine (pneumococcus, haemophilus influenzae b, meningococcus) for patients who might require splenectomy 1

Surgical Management by Tumor Type

Nonfunctioning Pancreatic NETs

  • Tumors <1 cm: Selected cases may be observed, especially if incidentally discovered 1
  • Tumors 1-2 cm: Resection with lymph node dissection due to risk of lymph node metastases (7-26%) 1
  • Tumors >2 cm or malignant-appearing: Complete resection with negative margins and regional lymph node removal 1
  • Surgical approach:
    • Head of pancreas: Pancreatoduodenectomy (Whipple procedure)
    • Body/tail: Distal pancreatectomy with or without splenectomy 1

Gastrinomas

  • Occult gastrinomas: Exploratory surgery with duodenotomy and intraoperative ultrasound 1
  • Duodenal gastrinomas: Duodenotomy with local resection/enucleation and periduodenal node dissection 1
  • Pancreatic head gastrinomas:
    • Exophytic/peripheral: Enucleation with periduodenal node removal
    • Deep/invasive/near pancreatic duct: Pancreatoduodenectomy 1
  • Distal pancreatic gastrinomas: Distal pancreatectomy with or without splenectomy 1

Insulinomas

  • All insulinomas: Surgical resection regardless of size due to metabolic complications 1
  • Peripheral insulinomas: Enucleation/local resection or spleen-preserving distal pancreatectomy 1

VIPomas and Glucagonomas

  • Small (<2 cm) peripheral tumors: Enucleation or local excision with lymph node dissection 1
  • Larger tumors or those in pancreatic head: Pancreatoduodenectomy with lymph node dissection 1
  • Tumors in distal pancreas: Distal pancreatectomy with splenectomy 1

Gastric NETs

  • Type 1 and 2 (hypergastrinemia-associated):
    • Tumors ≤2 cm: Endoscopic resection if feasible
    • Tumors >2 cm: Surgical resection 1
  • Type 3 (sporadic): Radical resection with regional lymphadenectomy 1

Small Intestinal NETs

  • Surgical resection of bowel with regional lymphadenectomy
  • Careful examination of entire bowel for multiple synchronous lesions 1
  • Consider prophylactic cholecystectomy if future treatment with somatostatin analogues is anticipated 1

Management of Metastatic Disease

  • Limited hepatic metastases: Consider surgical excision of both primary tumor and liver metastases 1
  • Symptomatic recurrence: Subtotal cytoreductive resection (>90% of tumor burden) can provide effective palliation 1
  • Unresectable disease: Consider systemic therapy options including biologically targeted agents (everolimus, sunitinib), somatostatin analogues, or chemotherapy 2

Important Considerations and Pitfalls

  1. Tumor grading is critical: Grade 2 NETs have significantly higher metastatic potential (up to 50%) compared to Grade 1 tumors, affecting surgical decision-making 3

  2. Multifocal disease: Thoroughly examine the entire bowel during surgery, as NETs (especially small bowel) can be multifocal in 15-30% of cases 1

  3. Carcinoid crisis prevention: Administer octreotide parenterally before anesthesia induction in patients with functional carcinoid tumors 1

  4. Cholecystectomy consideration: Recommended when performing surgery for advanced NETs in patients anticipated to receive long-term octreotide therapy due to increased risk of biliary symptoms 1

  5. Surveillance after resection: Disease recurrence occurs in 21-42% of patients with pancreatic NETs, sometimes after many years, necessitating long-term follow-up 1

  6. MEN1 syndrome: Special considerations for surgical approach in patients with multiple endocrine neoplasia type 1, who often have multiple tumors 1

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

3
Guideline

Neuroendocrine Tumors (NETs) Grade 2

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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