This information is about familial adenomatous polyposis, which is called FAP for short. FAP is a condition that can run in families. If it isn’t treated it increases a person’s chances of getting cancer of the bowel. With early treatment people with FAP can avoid bowel cancer and lead healthy lives.

FAP is a condition that runs in families. Conditions that run in families may be referred to as inherited or familial. People with FAP have an increased risk of getting cancer of the bowel. About 1 in every 100 of all bowel cancers are linked to FAP.

People with FAP have hundreds or thousands of small growths called polyps in the bowel. These are also sometimes called adenomas. This is where the adenomatosis part of FAP comes from and polyposis just means lots of polyps.

FAP can also affect people who don’t have a history of it within their family. This happens in about 1 in 3 people with FAP.

The polyps usually start to appear when you are in your teens. And if they aren’t treated one or more of them will almost certainly develop into cancer (usually by the age of 40). There’s a type of FAP called attenuated FAP in which the polyps appear about ten years later than with the usual FAP.

So, most people with FAP are offered the choice of having an operation to remove the bowel when they’re young. This can be hard to cope with but it means that you can avoid getting bowel cancer.

FAP can have some effects on other parts of the body. Most people have some harmless changes (like black dots) at the back of the eye (retina). They don’t affect your vision at all and often help to diagnose FAP.

Some people get harmless lumps which affect the bones or cysts on the skin.

You can also get polyps in the stomach. These are usually harmless but they will need to be checked regularly. There’s also a very slightly increased risk of getting cancer in other parts of the body (duodenum, thyroid, adrenal and pancreas). The risk is greatest for cancer of the small bowel (duodenum), but it’s still very low. You may have regular tests to check for this.

People with FAP also have a higher risk of developing a rare tumour called a desmoid tumour. It develops and grows in the fibrous tissue that covers muscle and other organs. It’s not a cancer and doesn’t spread to other parts of the body.

The bowel is part of our digestive system. It’s divided into two parts, the small bowel and the large bowel. The large bowel is made up of the colon and rectum.

The food we eat passes from the stomach, where it’s digested, into the small bowel. This is where the body absorbs the essential things we need from our food. The digested food then moves into the large bowel where water is absorbed and waste or stools are formed.

The first part of the bowel, which goes up, is called the ascending colon. It then goes across to the left side of the abdomen (the transverse colon). After this, it goes down to the bottom of the abdomen (the descending colon) and ends in the sigmoid colon, the rectum and anus.

FAP is caused by a fault in a gene called the APC gene. Our genes carry the information that’s passed on (inherited) from our parents. They decide things like the colour of our eyes and affect the way our bodies grow, work and look.

We have two copies of each gene – one from each of our parents. If someone has FAP it means they have a healthy gene but also one that’s faulty.

If that person has a child there is a fifty-fifty chance that they will pass on the faulty gene (only one copy of a gene is passed on from each parent). If a child has inherited the faulty gene they will develop FAP.

In about 1 in 3 people a faulty APC gene happens with no history of FAP in the family. Their children will still have a fifty-fifty chance of inheriting the faulty gene.

If you have a parent, or a brother or sister, with FAP you’ll have regular tests to check for it from a young age (10 onwards). But as FAP can also happen without any history of it in the family the first sign of it may be bowel symptoms.

People can have hundreds of polyps in their bowel without any symptoms. If these polyps go untreated then symptoms may eventually appear. But in some people there are no signs until a polyp has changed into a cancer.

Some of the symptoms of FAP and also bowel cancer are:

• blood or mucous in the stools or bleeding from the back passage
• diarrhoea or constipation (a lasting change in normal bowel habit)
• pain in the tummy (abdomen) or back passage
• losing weight for no obvious reason.

These symptoms can be caused by different conditions other than FAP or bowel cancer. It’s always important to get them checked out by your doctor.

Children and teenagers may be diagnosed with FAP because they’ve been having regular tests to check for it (they have a parent with FAP). Tests to look at the inside of the bowel are carried out every year.

As well as testing for polyps doctors look for other signs of FAP, like the changes it can cause at the back of the eye. People who have FAP in the family are usually diagnosed by a colonoscopy (test to look at the inside of the bowel).

Colonoscopy

A colonoscopy is usually done in the hospital outpatient department and takes about an hour. Your bowel has to be completely empty for the test. This means you’ll have to follow a low bulk diet for a few days before it. On the day before your test you will be asked to take medicine (a laxative) to empty your bowel. You will be given instructions about this by your hospital.

Just before the test, you will be given a drug to help you to feel more relaxed (sedative). This may be given as an injection into a vein (intravenously).

Once you are lying comfortably on your side, the doctor, or nurse, will gently pass a flexible tube (a colonoscope) into your back passage. A colonoscope is a long, thin flexible tube which has a tiny light and a camera on the end of it. It can easily pass around curves so most of the large bowel can be examined. During the test, photographs and samples of tissue (biopsies) can be taken. If there are hundreds of polyps lining the bowel it’s likely that you have FAP.

Afterwards, you’ll need somebody to go home with and stay with you for 24 hours until the effects of the sedative wear off.

It’s important not to drive during this time.

Genetic testing

It is possible to find out if someone has the faulty FAP gene by doing a genetic test.

The test is carried out first on a member of the family who has FAP. When their faulty gene has been found other family members can then be tested to find out if they have the same faulty gene. If the genetic test shows that the family member doesn’t have the faulty gene then bowel screening can be stopped. If you haven’t inherited the faulty gene your risk of getting bowel cancer is the same as anyone else’s.

Sometimes the faulty gene can’t be found in a person who has FAP. This means that their close family cannot be tested. But they will still have regular bowel checks (screening).

Families go through counselling before any genetic testing is done. This is so that they understand what the results will mean to them.

If someone in the family has FAP then their close family (children, sisters, brothers) will be offered screening. This can start from the age of 10 onwards. It means having a colonoscopy every year to check the lining of the bowel for polyps. If you have the faulty gene for FAP it’s likely that the polyps will appear before you are 20. Doctors will also be looking out for any signs of FAP affecting other parts of the body.

Screening can stop if genetic testing shows that you don’t have a copy of the faulty gene. Otherwise, it’s very important to carry on with your yearly bowel checks.

If you have FAP

When someone definitely has FAP they will carry on with bowel tests until they need to have surgery. They may also have tests (usually every one to two years) to check the small bowel (duodenum) and the stomach. This is because there’s still a risk of polyps developing in these areas.

People with a type of FAP called attenuated FAP may have regular tests (screening) for longer. They have fewer polyps and so bowel cancer usually develops later.

It’s very important to carry on having all your tests until you have made a decision about surgery. Your surgeon will talk to you about which operation would be best for you.

If the person is very young or the polyps look harmless they may continue with regular bowel checks for a while. But once there are lots of polyps in the bowel it’s impossible to know when one of these could become a cancer. So, an operation is the safest way to treat FAP and prevent bowel cancer.

Surgery

• Removing the colon It may be possible to remove the colon and join the small bowel to the top of rectum. This is called an ileo-rectal anastamosis (IRA).You can go to the toilet normally but more often than before. There is still a risk that polyps may develop in the rectum so you will need to have a test to check this every year.

• Removing the colon and rectum Sometimes the lining of the rectum is removed to avoid the risk of polyps developing. If the rectum is removed, a pouch to replace it can be made using a piece of the small bowel. This is a complex operation. After the surgery you can go to the toilet normally but usually more often than before. You might need to take anti-diarrhoea medicine. Tests on the rectum won’t be needed because the lining (where polyps grow) has been removed.

• Having a stoma Some people need to have the rectum removed. The end of the small bowel is brought out onto the skin of the tummy (abdomen). The opening is called a stoma and a bag is worn over it to collect bowel motions. It can take a while to get used to having a stoma. There are specialist nurses (stoma nurse) who can help and support you through this.

Having surgery for FAP can be very distressing. But it’s the best way to stop you from getting cancer of the bowel.

Having FAP or being at risk of it can be very difficult to cope with. There’s the uncertainty of not knowing whether FAP could develop into a cancer. There are often complicated decisions to be made about the right time to have surgery. Some people choose to have screening for longer because they find the thought of an operation very difficult. Others may choose to have surgery earlier because they find waiting for their screening hard. Talk to your doctor or nurse about any concerns you have.

FAP may affect you at a time when you’re already coping with changes like puberty. It’s often at a time when you’re trying to become more independent. All these things can cause different issues and affect your relationships.

You may have many different emotions including anxiety and fear. These are all normal reactions. Many people go through lots of different emotions when they’re trying to come to terms with their condition.

Everyone has their own way of coping with difficult situations. Some people find it helpful to discuss how they are feeling with a relative or a close friend, or with a counsellor. Many hospitals have specialist nurses who may be able to help you. You could contact the Familial Adenomatous Polyposis Support Group or IA - the Ileostomy and Internal Pouch Support Group or visit fapgene.org.uk which offers information and support to people affetced by FAP.

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

• An Introduction to FAP The Polyposis Registry at St Mark's Hospital, London, www.polyposisregistry.org.uk
• Risk Assessment and Management in Cancer Genetics. Lalloo F, B Kerr, J Friedman, D G Evans. Oxford University Press, 2005.

For further references, please see general bibliography.