A carcinoid tumour is a rare cancer of the neuroendocrine system, the body system that produces hormones.
The tumour usually grows in the gut (appendix, small intestine or large bowel), but it can also be found in the stomach, pancreas, lung, breast, kidney, ovaries or testicles. It tends to grow very slowly.
'Carcinoid syndrome' is the collection of symptoms some people get when a carcinoid tumour – usually one that has spread to the liver – releases hormones into the bloodstream.
The tumour produces too much of the hormone serotonin, as well as other chemicals that widen the blood vessels, which cause a wide range of symptoms (see below).
In the early stages of having a carcinoid tumour, you may not have any symptoms.
Also, you may not have symptoms if the tumour is just in your digestive system, as any hormones it produces will be destroyed by your liver.
If symptoms do develop, they tend to be fairly general and can be easily mistaken for signs of other illnesses.
Symptoms may result from both the tumour itself and from any hormones it releases into the bloodstream.
Symptoms will depend on where in the body the tumour develops.
A lung carcinoid tumour may cause:
A stomach carcinoid tumour may cause:
A bowel carcinoid tumour may cause:
An appendix carcinoid tumour doesn't tend to cause any symptoms; it's usually only discovered when the appendix is being removed for another reason.
Typical symptoms of carcinoid syndrome are:
These symptoms may come on unexpectedly as the hormones can be produced by the tumour at any time.
It is not currently understood why carcinoid tumours develop, but it's thought that most cases happen by chance.
However, some cases may run in families. According to Cancer Research UK, carcinoid tumours are likely to be more common in:
Read information by Cancer Research UK on the possible risk factors for carcinoid tumours.
A carcinoid tumour may be found incidentally – for example, as a surgeon is removing an appendix. In this case, the tumour will often be caught early and removed along with the appendix, causing no further problems.
Otherwise, people usually see their doctor after they have developed symptoms, and a carcinoid tumour may be diagnosed after carrying out a series of scans and tests, such as measuring the amount of serotonin in your urine and having an endoscopy. Learn more about the tests for carcinoid tumours.
There is currently no screening for carcinoid tumours in the UK.
If the tumour is in your digestive system or lung and it's caught early, it may be possible to completely remove it and cure the carcinoid syndrome altogether.
Otherwise, surgeons will remove as much of the tumour as possible (called 'debulking').
Read Cancer Research UK information on surgery for carcinoid tumours and staging for carcinoid tumours (to see how far it has grown or spread).
If the tumour cannot be removed, but it's not growing or causing symptoms, you may not need treatment straight away – it will just be carefully monitored.
If it is causing symptoms, you may be offered one of the below treatments.
Symptoms of carcinoid syndrome can also be treated – injections of octreotide and lanreotide (Somatuline) can slow down the production of hormones released by the tumour, and you may be given drugs to widen your airways (to relieve wheezing and breathlessness) and anti-diarrhoea medication.
There are things you can do yourself to manage some of the symptoms of carcinoid syndrome.
Generally, you should avoid the following things, which can all trigger or worsen flushing:
Learn more about triggers for flushing.
Some medications, such as selective serotonin reuptake inhibitor (SSRI) antidepressants, may make symptoms worse by further increasing your levels of serotonin – but never stop taking medication without seeking your doctor's advice.
It's important to keep drinking little and often if you have diarrhoea.
If the whole tumour can be surgically removed, this may cure the cancer and symptoms altogether.
Even if surgeons cannot remove all of the tumour, it usually grows slowly so that people have a good life expectancy compared to many other cancers.
The symptoms of carcinoid syndrome can be controlled and the growth of the tumour delayed with drugs such as octreotide and lanreotide so that most people can lead well and active lives, with only occasional symptoms.
That said, as the tumour gradually grows or spreads, it will produce more and more hormones and it may eventually be difficult to completely control symptoms with drugs. You may need further surgery or other treatments.
If the tumour has spread to your liver, lung, lymph nodes, or the lining of your abdomen, it's unlikely you'll be cured (it won't be possible to remove all the cancer). Life expectancy can be good, but you'll need to be carefully monitored.
Cancer Research UK has more information on statistics and outlook for carcinoid.
Some people with carcinoid syndrome may develop complications, outlined below, although these are rare:
Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.