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Carcinoid syndrome
About carcinoid syndrome

Carcinoid syndrome

Carcinoid syndrome is a possible complication in patients who have rare abdominal tumours called gastroenteropancreatic neuroendocrine tumours (GEP-NETs) if they spread to the liver.

GEP-NETs are a form of tumour found in the gastroenteropancreatic neuroendocrine system, which includes the pancreas and digestive system. For more information, visit our GEP-NETs page.

Carcinoid syndrome is a collection of symptoms that usually occurs in people with an advanced GEP-NET that has metastasised (spread) to the liver where it releases excessive amounts of hormones into the bloodstream.1-3 

Hormones are chemicals that coordinate different functions in your body, such as growth, mood, and metabolism. However, if you have too much of a particular hormone, it can cause major changes to your body.4

Carcinoid syndrome is the result of advanced GEP-NETs, so curing this form of cancer isn’t always possible. Therefore, treatment is often used to relieve your symptoms.2,3

image of a liver with a zoomed-in section showing a GEP-NET releasing hormones.

How many people have carcinoid syndrome?

In 100,000 people, on average you would expect to find between 2 and 5 people with GEP-NETs5

Of this number, only around 1 in 10 people will develop carcinoid syndrome6

References

  1. Macmillan. Carcinoid syndrome. Available at: https://www.macmillan.org.uk/cancer-information-and-support/impacts-of-cancer/carcinoid-syndrome. Last accessed April 2025.
  2. Mayo Clinic. Carcinoid syndrome. Available at: https://www.mayoclinic.org/diseases-conditions/carcinoid-syndrome/symptoms-causes/syc-20370666. Last accessed April 2025.
  3. NHS Inform. Carcinoid syndrome and carcinoid tumours. Available at: https://www.nhsinform.scot/illnesses-and-conditions/cancer/cancer-types-in-adults/carcinoid-syndrome-and-carcinoid-tumours/. Last accessed April 2025.
  4. Cleveland Clinic. Hormonal Imbalance. Available at: https://my.clevelandclinic.org/health/diseases/22673-hormonal-imbalance. Last accessed April 2025.
  5. Kizilgul M, Delibasi T. Review article: Gastroenteropancreatic neuroendocrine tumors (GEP-NETs). Transl Gastrointest Cancer 2015;4(1):39-56.
  6. Aluri V, Dillon JS. Biochemical Testing in Neuroendocrine Tumors. Endocrinol Metab Clin North Am. 2017;46(3):669-677.