A carcinoid tumour, sometimes referred to as simply 'carcinoid', is a tumour of the neuroendocrine system. The neuroendocrine system is a network of glands that produce hormones and send them into the bloodstream to affect the function of different organs in the body. 

Most carcinoid tumours (over 8 out of 10 – 85%) are found in the appendix or the small bowel (intestine). Less commonly, they may arise in the lung, kidney or the pancreas.

Carcinoid tumours often grow slowly and it may be several years before any symptoms appear and the tumour is diagnosed.

This is a rare type of tumour. As with many other forms of cancer, the exact cause is unknown. Approximately 1200 people are diagnosed with carcinoid tumours each year in the UK. They are usually found in adults over the age of 60 and men are affected slightly more than women. People who have a rare family syndrome called multiple endocrine neoplasia 1 (MEN1) have a slightly increased risk of developing a carcinoid tumour.

The type of symptoms will depend on where the tumour started, where it may have spread to, and whether it produces a hormone known as serotonin. If a carcinoid tumour starts in the appendix it does not usually spread to other parts of the body and does not produce serotonin. As a result there are very few symptoms and it is often discovered by chance when the appendix is removed for another reason.

If a carcinoid tumour starts outside the appendix, and particularly if it spreads to the liver, it will often produce serotonin and cause symptoms known as carcinoid syndrome. Symptoms include:

• diarrhoea
• flushing of the skin
• wheezing (similar to asthma)
• loss of appetite
• weight loss

It may be possible to reduce the symptoms of carcinoid syndrome by avoiding substances or conditions that cause flushing, such as alcohol and stress.

Before your doctor can make a firm diagnosis of a carcinoid tumour a number of tests will have to be done.

Urine test When serotonin is broken down in the liver, it is excreted as a chemical in the urine called 5HIAA. Your urine will be collected over a 24-hour period to check whether there are raised levels of 5HIAA.

Blood tests may be taken to check serotonin levels.

The doctor may also carry out a number of tests to find out whether the cancer has spread. These may include the following:

Chest x-ray This will show whether there has been any spread to the lungs.

Ultrasound scan A simple, painless scan which uses sound waves to form a picture of the inside of the abdomen.

CT (computerised tomography) scan A CT scan takes a series of x-rays which are fed into a computer to build up a three-dimensional picture of the inside of the body. It may be used to find where the cancer started (the primary tumour) or to check for any spread of the disease (secondaries or metastases).

The scan is painless but takes from 10 to 30 minutes. CT scans use a small amount of radiation, which will be very unlikely to harm you and will not harm anyone you come into contact with. You will be asked not to eat or drink for at least four hours before the scan.

Most people who have a CT scan are given a drink or injection to allow particular areas to be seen more clearly. Before having the injection or drink, it is important to tell the person doing this test if you are allergic to iodine or have asthma. You will probably be able to go home as soon as the scan is over.

MRI (magnetic resonance imaging) scan This test is similar to a CT scan, but uses magnetic fields instead of x-rays. During the scan you will be asked to lie very still on a couch inside a metal cylinder. The cylinder is a very powerful magnet, so before going into the room you should remove all metal belongings. You should also tell your doctor if you have ever worked with metal or in the metal industry or if you have any metal inside your body (for example, a cardiac monitor, pacemaker, surgical clips, or bone pins). You may not be able to have an MRI because of the magnetic fields.

You will usually be given an injection to allow the pictures to be seen more clearly.

The test can take about 30 minutes and is completely painless, although the machine is quite noisy. You will be given earplugs or headphones. If you don’t like enclosed spaces you may find the machine claustrophobic. A two-way intercom enables you to talk with the people controlling the scanner.

Octreotide scan An octreotide scan examines how several of your internal organs are working. Octreotide is a substance that is absorbed by carcinoid cells. It can show where a cancer started and any areas that it has spread to. The scan is done in the nuclear medicine department and takes place over three consecutive days.

On the first day you will go to the department twice. In the morning you will have an injection in your arm. You are then usually free to stay in or leave the hospital. In the afternoon you will have a scan taken using a gamma camera. The scan takes about an hour and during this time you will lie still on a bed. On the following two afternoons pictures will again be taken for up to one and a half hours.

123MIBG scan A drug called 123MIBG may be used to show up the site of a carcinoid tumour. 123MIBG is a mildly radioactive drug that is absorbed by carcinoid cells. The scan takes place over two consecutive days in the nuclear medicine department.

On the first day you will go to the department twice. In the morning you will be given an injection in the arm. You are then usually free to stay or leave the hospital. You will go back to the department in the afternoon to have a scan with a gamma camera lasting for about an hour. The following morning you will have further pictures taken for about one and a quarter hours. At this point you may be given a further injection of 123MIBG.

Biopsy A small sample of cells is taken from the tumour to be examined under a microscope. Depending on which part of the body is affected, a local or general anaesthetic is given.

The treatment for a carcinoid tumour depends on a number of factors including your general health and the size and position of the tumour. The results of your tests will enable your doctor to discuss the best type of treatment with you.

Consent

Before you have any treatment, your doctor will give you full information about what it involves and explain the aims of the treatment to you. They will usually ask you to sign a form saying that you give permission (consent) for the hospital staff to give you the treatment. No medical treatment can be given without your consent.

Benefits and disadvantages of treatment

Treatment can be given for different reasons and the potential benefits will vary for each person. If you have been offered treatment that aims to cure your cancer, deciding whether to have the treatment may not be difficult. However, if a cure is not possible and the treatment is to control the cancer for a period of time, it may be more difficult to decide whether or not to go ahead.

If you feel that you can't make a decision about treatment when it is first explained to you, you can always ask for more time to decide.

You are free to choose not to have the treatment and the staff can explain what may happen if you don't have it. You don't have to give a reason for not wanting to have treatment, but it can be helpful to let the staff know your concerns so that they can give you the best advice.

Surgery

If the tumour is contained in one area (localised), or if there has been only limited spread (regional), surgery is usually the first choice of treatment. If it is possible to remove the tumour completely no other treatment may be necessary.

If the tumour has spread to other parts of the body (metastatic) but there are only one or two areas – for example, in the liver – surgery may still be possible because of the slow growth of the tumour.

Chemotherapy

Chemotherapy is the use of anti-cancer (cytotoxic) drugs to destroy cancer cells. It may sometimes be used to treat carcinoid tumours that have spread, with the intention of reducing the tumour and the secretion of serotonin, and of prolonging a good quality of life.

Interferon

Another type of drug treatment for the symptoms of carcinoid tumours is interferon, which is a biological therapy. Interferon is given as an injection under the skin. At first it can cause flu-like symptoms such as chills, fever, aching joints and tiredness, but these usually disappear.

Radiotherapy

For this treatment, high-energy rays are used to destroy cancer cells. Radiotherapy is usually given to treat symptoms, such as pain, which may occur if the tumour has spread to the bones.

Hepatic artery embolisation

This treatment may be used to slow down the growth of secondary liver tumours (metastases) by reducing the blood supply to the tumours in the liver. The tumours cannot survive without a blood supply.

This procedure usually requires an anaesthetic, and you will probably have to stay in hospital overnight. The doctor will gently push a thin tube into the main blood vessel in your groin (the femoral artery). Using a scan, the doctor slowly guides the tube into the main blood vessel of the liver (hepatic artery). They will then inject a drug that blocks the blood supply (embolises it). Sometimes this is combined with chemotherapy.

You may feel unwell and your temperature may be raised for a few days afterwards. Your doctor or nurse can give you more information.

131MIBG

Another drug, 131MIBG, may be used to reduce the number of carcinoid cells and the symptoms of carcinoid syndrome. It gives a dose of radiotherapy to the carcinoid cells, and is known as targeted radiotherapy. This treatment can be given as a drink or as an injection into the vein.

Radio-labelled octreotide

Octreotide is absorbed by carcinoid cells. A small dose of radioactivity can be attached to it. This treatment is given as an injection into a vein in the arm. Again, it can reduce the number of carcinoid cells.

Radiofrequency ablation

Radiofrequency ablation may be used in some situations where the tumour is affecting the liver. It uses laser or radiowaves (microwaves) to destroy the cancer cells by heating them to high temperatures. A sedative drug is given to make the person feel drowsy and a local anaesthetic is used to numb the skin of the abdomen. A fine needle is then inserted through the skin over the liver and into the centre of the tumour. Powerful laser light or radiowaves are then passed through the needle and into the tumour, which heats the cancer cells and destroys them.

Somatostatin analogues

Carcinoid syndrome can be treated with drugs known as somatostatin analogues. These work by reducing the production of hormones by the tumour, and can help to reduce the flushing and diarrhoea.

The somatostatin analogue octreotide (Sandostatin®) is given as a short-acting injection under the skin up to three times a day. Most people are taught how to give the injection themselves.

Other somatostatin analogues are given as longer-acting injections into the muscle (intramuscular) between 7 to 28 days apart, depending on the drug that is used and the response. Commonly used drugs are octreotide (Sandostatin Lar®) and lanreotide (Somatuline® LA, Somatuline Autogel®).

Research into treatments for carcinoid tumours is ongoing and advances are being made. Cancer doctors use clinical trials to assess new treatments.

You may be asked to take part in a clinical trial. Your doctor must discuss the treatment with you, so that you have a full understanding of the trial and what it means to take part.

During your diagnosis and treatment you are likely to experience a number of different emotions, from shock and disbelief to fear and anger. At times these emotions can be overwhelming and hard to control. It is quite natural, and important, to be able to express them. Everyone has their own ways of coping with difficult situations; some people find it helpful to talk to friends or family, while others prefer to seek help from people outside their situation. Others prefer to keep their feelings to themselves. There is no right or wrong way to cope, but help is available if you need it.

This section has been compiled using information from a number of reliable sources, including:

• Cancer - Principles and Practice of Oncology (8th Edition). DeVita et al, Lippincott, Williams and Wilkins, 2008.
• Gastrointestinal Oncology: Principles and Practice. Kelsen et al. Lippincott Williams and Wilkins, 2002.
• The Textbook of Uncommon Cancers (3rd edition). Raghavan et al. Wiley, 2006.

For further references, please see the general bibliography.