Initial Management of Neoplastic Gastrointestinal Neuroendocrine Tumor

Diagnostic Workup

Baseline tests should include plasma chromogranin A and 24-hour urinary 5-hydroxyindoleacetic acid to assist in diagnosis and provide prognostic information, as recommended by the European Neuroendocrine Tumor Society 1, 2
Additional specific biochemical tests should be requested depending on suspected syndrome, including fasting gut hormones, gastrin, insulin, glucagon, and vasoactive intestinal peptide, according to the European Neuroendocrine Tumor Society 1, 2
Serum pancreatic polypeptide may be useful as it is found in high concentrations in 80% of pancreatic tumors and 50% of carcinoid tumors, as noted by the European Neuroendocrine Tumor Society 1
A multi-modality approach is recommended for detecting the primary tumor and assessing disease extent, including CT and MRI for anatomical localization and staging, as suggested by the European Neuroendocrine Tumor Society 2, 3
Somatostatin receptor scintigraphy is essential for detecting metastases with sensitivity of 61-96% and predicting response to somatostatin analogue therapy, as recommended by the European Neuroendocrine Tumor Society 2, 3
Endoscopic ultrasound is a major diagnostic tool, particularly for pancreatic NETs, according to the European Neuroendocrine Tumor Society 3
68Ga PET/CT is the most sensitive imaging modality where available, as noted by the European Neuroendocrine Tumor Society 2

Histopathological confirmation is mandatory to classify the tumor according to WHO classification, including immunohistochemical profile with neuroendocrine markers and Ki-67 proliferation index, as recommended by the World Health Organization 5, 2
The pathology report should include tumor size, invasion depth, and margin status, according to the World Health Organization 5

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, as recommended by the European Neuroendocrine Tumor Society 2
Complete removal of the primary tumor with negative margins and regional lymph node dissection should be performed, according to the European Neuroendocrine Tumor Society 4
For patients who are not fit for surgery, the aim of treatment is to improve symptoms and maintain optimal quality of life, using treatment options such as somatostatin analogues and locoregional treatments, as suggested by the European Neuroendocrine Tumor Society 2

Regular follow-up with biochemical markers and conventional imaging every 3-6 months for G1/G2 tumors is recommended, as suggested by the European Neuroendocrine Tumor Society 4
Somatostatin receptor imaging is recommended after 18-24 months if somatostatin receptor expression is confirmed, according to the European Neuroendocrine Tumor Society 4

Mesenteric fibrosis may cause small bowel obstruction and requires close monitoring, as noted by the European Neuroendocrine Tumor Society 7
Carcinoid heart disease may develop if carcinoid syndrome has been present for years, according to the European Neuroendocrine Tumor Society 8
Carcinoid crisis can be precipitated by anesthetic induction, tumor manipulation, or invasive procedures, as recommended by the European Neuroendocrine Tumor Society 9

Overall five-year survival of all NET cases is approximately 67.2%, as reported by the European Neuroendocrine Tumor Society 9