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Familial Adenomatous Polyposis

  • Amy Scholten, MPH
Publication Type:


Familial Adenomatous Polyposis



Familial adenomatous polyposis (FAP) is a rare disease where hundreds of polyps form in the colon and rectum. Without treatment, people with FAP go on to develop colorectal cancer. They may also develop harmless or cancerous growths in other organs.

Colon Polyp

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FAP is caused by a problem in a certain gene. Polyps start growing mainly during the teen years. Nearly all people with FAP will have polyps by age 35, and colon or rectal cancer before age 40.

Risk Factors

The risk for FAP are highest for people who have FAP in their families. FAP can also happen without family members having it. This is caused by new changes in the gene.


FAP may not cause symptoms at first. When they appear, symptoms may be:

  • Rectal bleeding
  • Blood in the stool (poop)
  • Loose stools
  • Cramping pain in the belly
  • Bloating
  • Weight loss
  • Feeling tired


The doctor will ask about symptoms and past health. A physical exam will be done. The doctor may check the rectal area with a gloved finger.

Diagnosis of FAP is based on tests such as:

  • Endoscopy—a lighted scope to look inside the colon and rectum. Tissue samples are taken at this time and tested for cancer.
  • Tests to check genes
  • An eye exam to look for changes in the back part of the eye


FAP is treated with surgery. Since FAP causes so many polyps, they cannot be removed one by one. The goal of surgery is to remove the part of the colon that contains them. The type depends on how much of the colon has polyps. Surgery may include:

  • Colectomy with ileorectal anastomosis—The colon is taken out. The last part of the small intestine is connected to the rectum. Bowel use will stay.
  • Restorative proctocolectomy—The colon and rectum are taken out. A pouch is made with the last part of the small intestine. The pouch works like a rectum. Bowel use will stay.
  • Total proctocolectomy with a colostomy —The colon is taken out. A colostomy is needed. This makes a path for solid waste to pass from the body through the belly wall. A special bag collects the waste.

Medicines such as nonsteroidal anti-inflammatory drugs (NSAIDs) may be used to shrink the polyps. They can also keep new ones from forming.


There is no way to prevent FAP.





  • Aelvoet AS, Buttitta F, et al. Management of familial adenomatous polyposis and MUTYH-associated polyposis; new insights. Best Pract Res Clin Gastroenterol. 2022;58-59:101793
  • Familial adenomatous polyposis. Cleveland Clinic website. Available at:
  • Familial adenomatous polyposis. EBSCO DynaMed website. Available at:
  • Familial adenomatous polyposis. Johns Hopkins Medicine website. Available at:
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This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.