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Neuroendocrine tumours and carcinoid syndrome

Neuroendocrine tumours (NETs) are rare tumours of the neuroendocrine system, the system in the body that produces hormones. They can be cancerous or non-cancerous.


Neuroendocrine tumours are sometimes referred to as carcinoid tumours, particularly when they affect the small bowel, large bowel or appendix.

Carcinoid syndrome is the collection of symptoms some people get when a neuroendocrine tumour, usually one that has spread to the liver, releases hormones such as serotonin into the bloodstream.

About 2,900 people are diagnosed with a neuroendocrine tumour each year in the UK, but not everyone with a tumour will have carcinoid syndrome.

Cancer Research UK has more information about different types of neuroendocrine tumours.


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Signs and symptoms

In the early stages of having a neuroendocrine tumour, you may not have any symptoms.




Symptoms caused by the tumour

Symptoms will depend on where in the body the tumour develops:


For example, a tumour in the appendix may only be found when the appendix is being removed for another reason.

Symptoms caused by the hormones (carcinoid syndrome)

Typical symptoms of carcinoid syndrome include:

  • diarrhoea, tummy pain and loss of appetite
  • flushing of the skin, particularly the face
  • fast heart rate
  • breathlessness and wheezing




What causes neuroendocrine tumours?

It's not known exactly why neuroendocrine tumours develop, but it's thought that most occur by chance.

Your chances of developing a neuroendocrine tumour may be increased if you have:

  • a rare family syndrome called multiple endocrine neoplasia type 1 (MEN1)
  • parents or siblings (brothers or sisters) with a carcinoid tumour
  • parents with non-Hodgkin lymphoma or cancer of the brain, breast, liver, bladder or endocrine system
  • conditions called neurofibromatosis or tuberous sclerosis

You can read more about the risks and causes of neuroendocrine tumours on the Cancer Research UK website.

Diagnosing neuroendocrine tumours

A neuroendocrine tumour may be found incidentally – for example, as a surgeon is removing an appendix.


Otherwise, people usually see their GP after they have developed symptoms.


Treating neuroendocrine tumours and carcinoid syndrome



You can read more about the surgery for neuroendocrine tumours on the Cancer Research UK website.

If the tumour can't be removed, but it's not growing or causing symptoms, you may not need treatment straight away – it might just be carefully monitored. 




What can I do to help myself?


Generally, you should avoid triggers of flushing, such as:

  • alcohol
  • large meals
  • spicy foods
  • stress


But never stop taking medication without seeking medical advice.




But even if surgeons can't remove the entire tumour, it usually grows slowly and can be controlled with medication.

Overall, people with neuroendocrine tumours have a good life expectancy compared with many other cancers. Many people remain relatively well and lead active lives, with only occasional symptoms.


Unfortunately, life expectancy isn't as good for a cancerous tumour that's spread to other parts of your body because it won't usually be possible to remove all of it. But treatment can still control your symptoms and slow down the spread of cancer.

You can read more about the survival statistics for neuroendocrine tumours on the Cancer Research UK website.