• Defined by their histological appearance.
• Chromaffin (Kulchitsky's) cells
• Incidence ~ 10 per 100,000 per year
• Prevalence ~ patients rarely cured but live for many years (up to 15)
• At post mortem 6500 per million, suggests many asymptomatic

Carcinoid syndrome ~ 3 - 5%, as a result of peptide products by- passing hepatic degradation and entering the systemic circulation.
Main substance responsible for the syndrome is serotonin.
Other substances implicated; bradykinin and substance P.

Carcinoid localization:

• Foregut

1. Bronchus ~10%
2. Stomach, duodenum <5%

• Midgut

1. Pancreas < 10%
2. Small bowel ~ 25%
3. Appendix ~ 40%

• Hindgut

1. Colon ~ 5%
2. Rectum ~ 15%
3. Gonads ~ 1%

Carcinoid syndrome symptoms:

• Flushing ~ 95%

1. face, neck and upper trunk

• GI

1. secretory diarrhoea, cachexia

• Respiratory

1. bronchospasm, pleural fibrosis

• Endocardial fibrosis ~ 50%

1. tricuspid regurgitation

• Pellegra ~ 10% (niacin deficiency)
• Arthritis, myopathy

Carcinoid syndrome diagnosis:

• Raised 5HIAA 24 hour urine collection
• 88% specific
• CT, US and Levovist (microbubble contrast for US)
• Endoscopic US
• Octreotide scanning
• Visceral angiography

Treatment

• Codeine, loperamide
• Niacin
• Octreotide
• Hepatic embolisation
• Surgery
• Chemotherapy - Streptozotocin and 5FU
• Interferon alpha

Somatostatin analogues:

• Octreotide administered sc every 8 hours
• Lanreotide LA every 14 days im
• Octreotide LAR every 28 days im
• Originally licensed for acromegaly
• 90% response rate with hormone syndromes
• Carcinoid and VIPoma crises
• Insulinoma: only 50% have octreotide binding sites
• Few side effects
• Biliary stasis, steatorrhoea
• Resistance develops with increasing tumour burden

Hepatic embolisation.

• Dual supply to normal liver, hepatic artery, portal vein
• Metastases supplied only by hepatic artery
• Method - Occlusion of hepatic artery tumour collateral. Covered with antibiotics and octreotide
• Response rates 60-80%
• Repeatable
• Complications

1. Sepsis
2. Renal Failure
3. Infarction of the gallbladder
4. Fluid imbalance