Familial Adenomatous Polyposis

Familial Adenomatous Polyposis (FAP) is an inherited bowel cancer syndrome. People with FAP are at high risk of developing bowel cancer much earlier than the general population.

For more detailed information download the Familial Adenomatous Polyposis (FAP) Information Guide (PDF).

What is Familial Adenomatous Polyposis (FAP)?

Familial Adenomatous Polyposis is caused by a change (mutation) in the APC gene. Everyone has two copies of the APC gene, but people with FAP have one working copy and one non-working copy.

People with Familial Adenomatous Polyposis develop 100s to 1000s of polyps in the large bowel (intestine)—polyps are small mushroom-like growths with stalks that vary in size from a tiny pinhead to 2 cm or more. Most people with Familial Adenomatous Polyposis develop bowel polyps by their late teens, although polyps may develop at any age. Some polyps are likely to become cancerous if left untreated, while others remain benign.

If your parent or a brother or sister has Familial Adenomatous Polyposis you may also have inherited FAP.

If you have Familial Adenomatous Polyposis your children each have a 50:50 chance of inheriting FAP from you.

Not all people with Familial Adenomatous Polyposis have a family history it. Some people are the first in their family to have FAP. If you are the first one in your family to have FAP, each of your children have a 50:50 chance of inheriting it.

Are there other signs of Familial Adenomatous Polyposis?

• Freckles in the eye—Some people with FAP have tiny freckles at the back of the eye (known as congenital hypertrophy of the retinal pigment epithelium—CHRPE). The freckles will not affect your vision or develop into cancer.
• Polyps in other places—Polyps can develop in other parts of the gut, including the stomach and duodenum.
• Gardner 's syndrome—Gardner's syndrome is a variation of FAP, also caused by a mutation in the APC gene. The main indication of Gardner's Syndrome is small cysts and benign (non-cancerous) growths in the bones, particularly on the jaw. Lumps also occur below the skin, on the face, or the scalp. Occasionally individuals have missing, extra or impacted teeth.
• Desmoid tumours—Desmoid tumours are benign tumours (non-cancerous) and are commonly found within the wall or lining of the abdomen. Desmoids are slow growing and do not spread; they only become a problem as they get larger and interfere with the functioning of other organs.

Management

Talk to your specialist about the best screening program for you.

Regular check-ups

People diagnosed with Familial Adenomatous Polyposis will require regular check-ups to help reduce the risk of developing bowel cancer.

For most people with FAP, a colectomy (surgical removal of all or part of the colon) is recommended by the age of 20. If you have not yet had a colectomy, you should have a colonoscopy every year to check for polyps. This is a procedure where a long flexible tube is used to examine the lining of your colon (large intestine).

Following surgery, a sigmoidoscopy (a procedure in which a long flexible tube is used to view the remaining colon and or/rectum) should be performed every 12 months.

If a pelvic pouch operation was performed when the colon was removed, the pouch should be examined annually.

Please visit the eviQ website for the latest Risk Management guidelines for Familial Adenomatous Polyposis (FAP). There is also a fact sheet for people and families with FAP.

If a close relative is diagnosed with Familial Adenomatous Polyposis you may be at risk of developing FAP. People at risk of FAP should have a colonoscopy every year starting from age 10–15 years. If no polyps have been found by age 25, screening may be reduced to every 2 years.

Types of surgery

There are several surgical options for people with Familial Adenomatous Polyposis (FAP):

• Ileorectal Anastomosis and Colectomy—removal of the entire colon. The end of the small bowel (ileum) is joined to the rectum.
• Restorative Proctocolectomy—removal of the entire colon, most of the rectum and its lining. A new rectum (called a pouch) is made and this is joined to the anus.
• Proctocolectomy & Ileostomy—removal of the entire colon, rectum and anus. The end of the small bowel (ileum) is joined to the wall of the abdomen, opening to the outside (known as a stoma) to allow bowel motions to pass out.

Talk to your surgeon about the best treatment for you.

Genetic testing

Changes (mutations) in the APC gene can lead to the development of Familial Adenomatous Polyposis.

If an APC gene mutation is identified in your family (in someone who has FAP) other relatives can be offered predictive genetic testing. Predictive testing can be done even though you may not have any signs or symptoms yet.

Sometimes a gene mutation cannot be found in the family. In this case, FAP may be due to other gene changes that research has not yet identified. If the family gene mutation is not found, predictive testing is not able to be offered to other family members.

A blood test is needed for genetic testing. For further information speak with a Genetic Counsellor.

What is attenuated Familial Adenomatous Polyposis (FAP)?

A rare form of Familial Adenomatous Polyposis called Attenuated FAP occurs in some people.

Attenuated FAP involves polyps—generally less than 100—and people with attenuated FAP will typically develop polyps and/or cancer later than people with classic FAP.

If you are diagnosed with this condition, you are still strongly predisposed to colorectal cancer.

Speak to your doctor or Genetic Counsellor about your risks and management.

What if I suspect I have Familial Adenomatous Polyposis (FAP)?

Speak to your doctor, a Genetic Counsellor or call the Hereditary Cancer Registry on 1800 505 644.