Carcinoid Tumors with Highest Rate of Metastasis

Evidence for Metastatic Rates by Primary Site

Ileal carcinoids demonstrate a 60% rate of nodal metastases and 30% rate of liver metastases, according to comprehensive guidelines on neuroendocrine tumors, as recommended by the National Comprehensive Cancer Network 1
Appendiceal carcinoids have only a 5% rate of nodal metastases and 2% rate of liver metastases, as reported by the National Comprehensive Cancer Network 1
Bronchial carcinoids show a 15% rate of nodal metastases and only 5% rate of liver metastases, according to the National Comprehensive Cancer Network 1
Gastric carcinoids demonstrate a 35% rate of nodal metastases and 15% rate of liver metastases, as stated by the National Comprehensive Cancer Network 1

Ileal carcinoids are part of the midgut carcinoid group, which has a higher propensity for metastatic spread compared to foregut and hindgut carcinoids, as noted by the National Comprehensive Cancer Network 2, 3
Ileal carcinoids frequently metastasize to mesenteric lymph nodes and the liver, which can lead to carcinoid syndrome when vasoactive substances bypass hepatic metabolism, according to the National Comprehensive Cancer Network 4, 5

Carcinoid tumors arising from the small intestine, including the ileum, are more commonly associated with carcinoid syndrome due to their propensity to metastasize to the liver, as reported by the National Comprehensive Cancer Network 3, 4
The metabolic products released by intestinal carcinoid tumors are normally destroyed by liver enzymes in the portal circulation, but with liver metastases, these substances enter directly into the systemic circulation, as explained by the National Comprehensive Cancer Network 6

Right colon carcinoids show high metastatic rates, with 70% nodal and 40% liver metastases, supporting the aggressive nature of midgut carcinoids, as stated by the National Comprehensive Cancer Network 1
Appendiceal carcinoids have the lowest metastatic potential among gastrointestinal carcinoids, with only 5% nodal and 2% liver metastases, as reported by the National Comprehensive Cancer Network 1
Rectal carcinoids have relatively low metastatic rates, with 15% nodal and 5% liver metastases, despite being common, according to the National Comprehensive Cancer Network 1

Patients with ileal carcinoids require thorough evaluation for metastatic disease at diagnosis, including multiphase CT or MRI scans for liver metastases, as recommended by the National Comprehensive Cancer Network 7, 5
Somatostatin receptor scintigraphy is particularly useful in evaluating the extent of disease in ileal carcinoids due to their high expression of somatostatin receptors, as noted by the National Comprehensive Cancer Network 5
Surgical resection remains the primary treatment approach for localized carcinoid tumors, regardless of site, as stated by the National Comprehensive Cancer Network 5