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Carcinoid Syndrome and Carcinoid Tumors

A carcinoid tumor is a rare cancer of the neuroendocrine system – the body system that produces hormones.

The tumor usually grows in the bowels or appendix, 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 tumor – usually one that has spread to the liver – releases hormones such as serotonin into the bloodstream.

Signs and symptoms

In the early stages of having a carcinoid tumor, you may not have any symptoms. You may also not have symptoms if the tumor is just in your digestive system, as any hormones it produces will be broken down 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 tumor itself and from any hormones it releases into the bloodstream.

Symptoms caused by the tumor

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

  • a bowel carcinoid tumor may cause tummy pain, a blocked bowel (diarrhea, constipation, feeling or being sick) and bleeding from the bottom (rectal bleeding)
  • a lung carcinoid tumor may cause a cough, which may make you cough up blood, and cause wheezing, breathlessness, chest pain and tiredness
  • a stomach carcinoid tumor may cause pain, weight loss, tiredness and weakness

Some tumors may not cause any symptoms and are discovered by chance. For example, an appendix carcinoid tumor 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:

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

These symptoms may come on unexpectedly, as the hormones can be produced by the tumor at any time.

Some people may also develop carcinoid heart disease, where the heart valves thicken and stop working properly. There is also a risk of developing a rare but serious reaction called a carcinoid crisis, which involves severe flushing, breathlessness and a drop in blood pressure.

What causes carcinoid tumors?

It’s not known exactly why carcinoid tumors develop, but it’s thought that most occur by chance.

Your chances of developing a carcinoid tumor may be increased if you have:

  • a rare family syndrome called multiple endocrine neoplasia type 1 (MEN1)
  • parents or siblings with a carcinoid tumour
  • parents with squamous cell skin cancer, non-Hodgkin’s lymphoma, or cancer of the brain, breast, liver, womb, bladder or kidney
  • conditions called neurofibromatosis or tuberous sclerosis

Diagnosing carcinoid tumors

A carcinoid tumor may be found incidentally – for example, as a surgeon is removing an appendix. In this case, the tumor will often be caught early and removed along with the appendix, causing no further problems.

Otherwise, people usually speak to their GP after they have developed symptoms. A carcinoid tumor may be diagnosed after carrying out a series of scans and tests, which may include measuring the amount of serotonin in your urine and having an endoscopy.

Treating carcinoid tumors and carcinoid syndrome

If the tumor is caught early, it may be possible to completely remove it and cure the cancer altogether. Otherwise, surgeons will remove as much of the tumor as possible (debulking).

If the tumor cannot be removed, but it’s not growing or causing symptoms, you may not need treatment straight away – it might just be carefully monitored. 

If it’s causing symptoms, you may be offered one of the following treatments:

  • injections of medicines called somatostatin analogues, such as octreotide and lanreotide, which can slow down the growth of the tumor
  • radiotherapy to kill some of the cancer cells
  • a procedure to block the blood supply to the tumor (for tumors in the liver), known as hepatic artery embolisation
  • a procedure that uses a heated probe to kill cancer cells (for tumors in the liver), called radiofrequency ablation
  • chemotherapy to shrink the tumor and control your symptoms

Symptoms of carcinoid syndrome can be treated with injections of octreotide and lanreotide. You may also be given medication to widen your airways (to relieve wheezing and breathlessness) and anti-diarrhoea medication.

What can I do to help myself?

There are things you can do yourself to manage some of the symptoms of carcinoid syndrome.

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

  • alcohol
  • large meals
  • spicy foods
  • foods containing the substance tyramine, such as aged cheese and salted or pickled meats
  • stress

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 medical advice.

If you have diarrhoea, it’s important to keep drinking little and often to avoid dehydration.


If the whole tumor can be removed, this may cure the cancer and symptoms altogether. But even if surgeons cannot remove the entire tumour, it usually grows slowly and can be controlled with medication.

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

But as the tumor grows or spreads, it will produce more and more hormones, and it may eventually be difficult to completely control symptoms with medication. You may need further surgery or other treatments.

Unfortunately, life expectancy is not as good for cancer that has spread to other parts of your body, because it won’t usually be possible to remove all of it. However, treatment can still control your symptoms and slow down the spread of cancer.