Risks and causes of carcinoid tumours

A risk factor is anything that can increase your chance of developing cancer. Different cancers have different risk factors.

Remember that having one or more risk factors does not mean that you will definitely get carcinoid. Many people with one or more risk factors never get carcinoid. And some people with none of the risk factors do develop carcinoid. Risk factors are only a guide to what may increase your risk.

Carcinoid tumours are rare. Only 1,200 people are diagnosed each year in the UK. Carcinoid is slightly more common in men than women. It is most common in middle aged people, although anyone can develop it at any age. Unfortunately, there is very little information about what causes carcinoid, or increases your risk of developing it. Doctors think that most cases happen by chance.

Carcinoid tumours develop more often than usual in people who have a rare family syndrome called multiple endocrine neoplasia type 1 (MEN1). 1 in 10 people with MEN1 (10%) develop carcinoid tumours and they also have a higher risk than normal of tumours of the pituitary gland, pancreas and parathyroid gland. Your doctors may ask you about your family history of cancer to check if there are any other people with cancer in your family.

A large study has shown that children of parents with carcinoid tumour have a risk of carcinoid tumour that is 4 times higher than the general population. People with a brother or sister with carcinoid have a risk that is 3 times higher. But as carcinoid tumours are very rare this risk is still small. Less than 1 in 100 people (1%) diagnosed with carcinoid tumour have a family member with carcinoid. 

People also have an increased risk of carcinoid tumour if they have a parent with squamous cell skin cancer, non Hodgkin lymphoma, or cancer of the brain, breast, liver, womb, bladder or kidney. People with a brother or sister diagnosed with bowel cancer or cervical cancer also have an increased risk of carcinoid tumours.

People who have a condition called neurofibromatosis also have a higher than normal risk of getting a carcinoid tumour of the stomach.

Carcinoid is slightly more common in black people of African descent than in white people.

Slightly more women than men develop carcinoid.

A US study found that people who have diabetes for a long time have an increased risk of carcinoid tumours in the stomach. The risk is especially increased in women.

If you have had a long term inflammation of the stomach lining called chronic atrophic gastritis you have a slightly higher risk of carcinoid of the stomach.

You also have a higher risk of stomach carcinoid if you have MEN1 and a condition called Zollinger Ellison syndrome, in which the stomach lining makes more stomach acid. 

Some factors have been studied but it is not clear whether they increase the risk of carcinoid tumours. These include

• Saturated fats
• Smoking
• Tuberous sclerosis

Saturated fats

A Swedish study has shown that people who eat a lot of saturated fat have a risk of carcinoid tumours of the stomach that is 3 or 4 times higher than people who have low levels of saturated fat in their diet. But we need more research to really know whether dietary fats affect the risk of carcinoid tumours.

Smoking

A small European study found that people who smoke have an increased risk of developing carcinoid of the small bowel and atypical lung carcinoids compared to non smokers. But we need bigger studies to confirm this.

Tuberous sclerosis

Tuberous sclerosis is a genetic condition caused by a change in a gene. The symptoms vary from one person to another, with some people showing very few symptoms and others more severely affected. People may have non cancerous growths in different organs of the body, such as the brain, heart, eyes, skin, kidneys, or lungs. Some may also have epilepsy, learning disabilities, autism spectrum disorder and kidney problems. People with tuberous sclerosis may have an increased risk of carcinoid tumours but both conditions are very rare and so it is difficult to be sure.