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Carcinoid is a rare tumour that begins in cells in the neuroendocrine system. About 80% of carcinoid tumours grow in the appendix and small bowel. But they can also develop in the pancreas, lungs, stomach, ovaries, kidneys or testicles. Carcinoid tumours grow at different rates but they’re usually very slow growing tumours. They may not grow or cause problems for months or years. However, some are aggressive and can quickly spread to other parts of the body and cause serious problems.
Signs and Symptoms of Carcinoid Tumors
In the early stages of having a carcinoid tumour, you may not have any symptoms. You may also not have symptoms if the tumour 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 tumour itself and from any hormones it releases into the bloodstream.
Symptoms caused by the tumour
Symptoms will depend on where in the body the tumour develops:
- A bowel carcinoid tumour may cause tummy pain, a blocked bowel (diarrhoea, constipation, feeling or being sick) and bleeding from the bottom (rectal bleeding).
- A lung carcinoid tumour may cause a cough, which may make you cough up blood, and cause wheezing, breathlessness, chest pain and tiredness.
- A stomach carcinoid tumour may cause pain, weight loss, tiredness and weakness.
Some tumours may not cause any symptoms and are discovered by chance. For example, an appendix carcinoid tumour 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
These symptoms may come on unexpectedly, as the hormones can be produced by the tumour 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.
Causes of Carcinoid Tumors
It’s not clear what causes carcinoid tumors. In general, cancer occurs when a cell develops mutations in its DNA. The mutations allow the cell to continue growing and dividing when healthy cells would normally die.
The accumulating cells form a tumor. Cancer cells can invade nearby healthy tissue and spread to other parts of the body.
Doctors don’t know what causes the mutations that can lead to carcinoid tumors. But they know that carcinoid tumors develop in neuroendocrine cells.
Neuroendocrine cells are found in various organs throughout the body. They perform some nerve cell functions and some hormone-producing endocrine cell functions. Some hormones that are produced by neuroendocrine cells are cortisol, histamine, insulin and serotonin.
Risk Factors for Carcinoid Tumors
Researchers are still learning about carcinoid tumors and what causes them. There are a few known risk factors for carcinoid tumors, and most are not factors you can control or change.
- Genetic syndromes. People with a rare genetic syndrome called Multiple Endocrine Neoplasia, type 1 (MEN1) have a higher risk of certain tumors, including carcinoid tumors. Those with a disease called neurofibromatosis type 1 are also at higher risk for developing carcinoid tumors.
- Gender. Women may be at slightly higher risk of developing carcinoid tumors. Researchers aren’t sure why.
- Race. Gastrointestinal carcinoid tumors are more common in African-American men and women than in Caucasians. But lung carcinoid tumors are more common in Caucasians than in people of other races.
- Stomach conditions. Those who have a stomach condition that reduces the amount of acid in the stomach and damages the stomach have a higher risk of carcinoid tumors in the stomach.
- Smoking. Smokers may be more likely to have certain types of lung carcinoid tumors. A recent study in Europe also found that smoking may double the risk of having a carcinoid tumor in the small intestine. But more research is needed to confirm these results.
Treatment for carcinoid tumours
If you have a slow-growing carcinoid tumour and it’s not causing any problems you probably won’t have treatment at first. Your doctor will keep a close eye on you and, if you develop symptoms, may decide to treat the tumour.
If you have a carcinoid that’s growing and causing symptoms there are several types of treatment your doctor may suggest. They include:
- biological therapy (interferon)
- other drugs known as somatostain analogues to help control the symptoms
- hepatic artery embolisation
- radiofrequency ablation.
The type of treatment you have will depend on where the carcinoid tumour is.