Initial Management of Neoplastic Gastrointestinal Neuroendocrine Tumor
For a 59-year-old patient with nausea and right lower quadrant cramping found to have a neoplastic gastrointestinal neuroendocrine tumor (NET), the initial management should include comprehensive biochemical testing, appropriate imaging studies, histopathological confirmation, and referral to a multidisciplinary team at a specialized center for definitive treatment planning.
Diagnostic Workup
Biochemical Assessment
- Baseline tests should include plasma chromogranin A (CgA) and 24-hour urinary 5-hydroxyindoleacetic acid (5-HIAA) to assist in diagnosis and provide prognostic information 1
- Additional specific biochemical tests should be requested depending on suspected syndrome, including fasting gut hormones, gastrin, insulin, glucagon, and vasoactive intestinal peptide (VIP) 1
- Serum pancreatic polypeptide may be useful as it is found in high concentrations in 80% of pancreatic tumors and 50% of carcinoid tumors 1
Imaging Studies
- A multi-modality approach is recommended for detecting the primary tumor and assessing disease extent 1
- CT and MRI should be performed for anatomical localization and staging 1, 2
- Somatostatin receptor scintigraphy (SSRS/octreoscan) is essential for detecting metastases with sensitivity of 61-96% and predicting response to somatostatin analogue therapy 1
- Endoscopic ultrasound (EUS) is a major diagnostic tool, particularly for pancreatic NETs 1
- 68Ga PET/CT is the most sensitive imaging modality where available 1
Histopathological Confirmation
- Histopathological confirmation is mandatory to classify the tumor according to WHO classification 1
- The pathology report should include:
Treatment Approach
Surgical Management
- Surgery should be offered when NETs are resectable with curative intent to patients who are fit and have limited disease to primary and regional lymph nodes 1, 2
- For tumors <2 cm, the risk of metastasis is lower, but surgical resection is still recommended 2
- Complete removal of the primary tumor with negative margins and regional lymph node dissection should be performed 2
- If potentially resectable metastatic disease is present, consider surgical resection if complete removal is feasible 2
Special Considerations
- For functioning tumors with carcinoid syndrome, prophylactic administration of octreotide is recommended 12 hours before and 48 hours after surgery to prevent carcinoid crisis 2
- Avoid medications that release histamine or activate the sympathetic nervous system during surgery 2
- If the patient is likely to receive long-term somatostatin analog therapy, cholecystectomy should be considered during abdominal surgery 1, 2
Non-Surgical Management
- For patients who are not fit for surgery, the aim of treatment is to improve symptoms and maintain optimal quality of life 1
- Treatment options for non-resectable disease include:
- Somatostatin analogues (octreotide, lanreotide) for symptom control and tumor stabilization 1, 3
- Targeted therapies such as everolimus or sunitinib for pancreatic NETs 4, 3
- Locoregional treatments including ablation and (chemo)embolization 1
- Peptide receptor radiotherapy with yttrium-90 or lutetium-177 3
Follow-up Plan
- Regular follow-up with biochemical markers and conventional imaging every 3-6 months for G1/G2 tumors 2
- Somatostatin receptor imaging is recommended after 18-24 months if somatostatin receptor expression is confirmed 2
- Monitor for development of carcinoid syndrome, which typically occurs when jejuno-ileal NETs metastasize to the liver 5
Potential Complications and Management
- Mesenteric fibrosis may cause small bowel obstruction and requires close monitoring 1
- Carcinoid heart disease may develop if carcinoid syndrome has been present for years 1
- Carcinoid crisis (profound flushing, bronchospasm, tachycardia, and widely fluctuating blood pressure) can be precipitated by anesthetic induction, tumor manipulation, or invasive procedures 1