Familial adenomatous polyposis (called “FAP”) is a disease that causes abnormal growths in the large intestine (also called the colon), rectum and other areas. Doctors call these growths “polyps.” They are not cancer, but can turn into cancer.

Most people with FAP have hundreds or thousands of polyps. This means they have a much higher risk of colon cancer than other people. Without treatment, almost all people who have FAP will develop colon cancer. Some people have a milder form of FAP that causes fewer polyps.

FAP is caused by an abnormal gene that runs in families. People who have FAP usually start showing signs of it in their teens or 20s, but some people get it in childhood. The average age at which an individual develops colon cancer in classic FAP is 39 years. Some people have a variant of the disorder, called attenuated familial adenomatous polyposis, in which polyp growth is delayed. The average age of colorectal cancer onset for attenuated familial adenomatous polyposis is 55 years.

Symptoms of FAP

  • FAP might not cause any symptoms. If it does, symptoms can include:

    • Bright red blood in bowel movements
    • Diarrhea – Runny, watery bowel movements
    • Constipation – Trouble having bowel movements
    • Belly cramps
    • Weight loss
    • Bloating – Feeling like the belly is full all the time
    • Tiredness
  • If someone in your family has FAP, you should have regular screening tests, which may include:

    • Colonscopy
    • Sigmoidoscopy
    • Upper Endoscopy
    • Genetic testing

If you have FAP, you should be tested for other types of cancer, as individuals with FAP have a higher risk of developing other forms of cancer. The second most common malignancy in patients with FAP is adenocarcinoma of the duodenum and the papilla of Vater. It affects as many as 12% of patients. Rarer cancers associated with FAP include medulloblastomas (Turcot syndrome), hepatoblastoma, thyroid cancer, gastric cancer, pancreatic cancer, and adrenal cancer.

Treatment Options for FAP

  • Surgery to remove the colon, or Colectomy – This is the main treatment for FAP.
  • Medication to slow polyp growth – The most common medical treatment is celecoxib (brand name: CeleBREX), which may be prescribed before or after a colectomy.
  • Polyp removal – In patients with milder forms of FAP, a physician can remove polyps during a colonoscopy or endoscopy.