Familial Adenomatous Polyposis

What is familial adenomatous polyposis?

Familial adenomatous polyposis (FAP) is a usually inherited disease that causes a large number of polyps to form in the large bowel.

Polyps are small, flesh-like growths that develop on the inner surface of the bowel. In patients with FAP the number of these polyps can run into hundreds, or even thousands.

The polyps do not have to be cancer at first. However, if it is not treated, the risk of large bowel cancer developing over time is very high.

For this reason, recognising the disease early and following it up regularly is vitally important.

Why does it happen?

FAP mostly comes from an inherited change in a gene called APC.

This gene normally helps to stop bowel cells multiplying out of control. When the gene is faulty, a large number of polyps can develop in the bowel.

The disease can be passed from mother or father to child. Each child of a person carrying FAP has a 50% chance of carrying the gene change that causes the disease.

However, in some patients FAP can appear even though no one in the family has had the disease before.

What are the symptoms?

The disease may cause no complaints at all for a long time. The polyps usually start to develop in childhood or young adulthood.

Some patients may have the following symptoms:

• Bleeding from the back passage
• Blood in the stool
• Abdominal pain
• Diarrhoea or a change in bowel habit
• Anaemia and tiredness

Important: having no complaints at all does not mean there are no polyps in the bowel.

How is it diagnosed?

One of the most important methods of diagnosis is colonoscopy.

During colonoscopy the inner surface of the large bowel is examined and a large number of polyps can be seen. When needed, biopsies are taken from the polyps.

A genetic test may be done to confirm the diagnosis and to find out the risk in family members.

Is there a treatment?

Yes. There are effective treatments for preventing large bowel cancer in patients with FAP.

Because the number of polyps is so large, it is often not possible to remove them all by colonoscopy.

For this reason, in a large proportion of patients it is recommended that the large bowel is removed by an operation before cancer develops.

The timing and type of the operation are decided according to the patient’s age, the number and size of the polyps and the pathology results.

Regular check-ups may also be needed after the operation.

Does it affect only the large bowel?

No. In patients with FAP, polyps can also develop in the stomach and particularly in the duodenum (the twelve-finger bowel).

For this reason, in some patients the upper digestive system also needs to be followed up with gastroscopy and special endoscopic examinations.

Should family members be checked?

Yes. Because this disease can be inherited, assessing family members is very important.

In particular, the children, brothers and sisters, and parents of people diagnosed with FAP should be assessed for genetic counselling and, when needed, genetic testing.

In children at risk, follow-up is usually started in childhood. When follow-up should start is decided according to the genetic finding in the family and the features of the disease.

When should you see a doctor?

If someone in your family has been diagnosed with FAP, you are advised to see a gastroenterologist even if you have no complaints at all.

If a large number of polyps is found at colonoscopy, an assessment for FAP should also be made.

Remember: FAP is a serious disease. However, with early diagnosis, suitable surgical treatment and regular follow-up, the risk of large bowel cancer developing can be greatly reduced.