Health Library

Familial Adenomatous Polyposis


Familial adenomatous polyposis (FAP) is a rare, inherited condition that causes colon and rectal cancer. FAP results in the development of hundreds of polyps inside the large intestine.

Colon Polyp
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FAP is caused by a genetic defect. Polyps usually begin developing during the teenage years. Nearly all people with FAP will have polyps by age 35. The average person with FAP will have colon or rectal cancer found by the age of 39 years.

Risk Factors

The primary risk factor for FAP is having family members with this condition. However, this condition can occur in people without a family history of the condition. This is because the genetic defect can be caused by a new mutation in the affected person.


In the early stages, there may be no symptoms. When symptoms do occur, they may include:

  • Rectal bleeding or blood in the stool
  • Diarrhea
  • Cramping pain in the stomach
  • Weight loss
  • Bloating
  • Fatigue


You will be asked about your symptoms and medical history. A physical exam will be done. An eye exam may also be done to look for lesions in the retina.

Your bodily fluids and tissues may be tested. This can be done with:

  • DNA analysis to look for the defective gene
  • Biopsy to see if polyps are cancerous

An endoscopy is a thin, lighted, telescope-like tube with a camera that is used to look for polyps inside the intestines. Endoscopy for FAP may include:

  • An exam of the stomach and the upper part of the small intestine
  • An exam of the rectum and colon


FAP is treated with surgery. Since FAP causes so many polyps, they cannot be removed individually. Therefore, the goal of surgery is to remove the portion of the intestine that contains the cancerous or precancerous polyps. The surgical procedure used depends on the length of intestine involved.


The 3 main surgical treatments are:

  • Colectomy with ileorectal anastomosis (IRA) —Removal of the colon except for a small section above the rectum. The last part of the small intestine is connected to the remaining part of the colon, preserving bowel function.
  • Restorative proctocolectomy (pouch)—Removal of the colon and rectum, leaving the anal canal. A pouch is created with the lower end of the small intestine. The pouch mimics the function of the rectum. The pouch is connected to the anal canal, preserving bowel function.
  • Total proctocolectomy with permanent ileostomy—Removal of the colon, rectum, and anal canal. A permanent ileostomy is created. An ileostomy is a surgical opening through the wall of the abdomen. It is used as a path for waste material to leave the body. After an ileostomy, you will wear a special bag to collect body waste.

Duodenal polyps in the small intestine are managed with endoscopy. An endoscope is used to find the polyps. Once found, the surgeon inserts small tools through a tube in the endoscope and removes them. In some cases, surgery to remove the duodenum may be done.


Medications are used shrink polyps and to prevent new ones from forming. Medications include:

  • Nonsteroidal anti-inflammatory drugs (NSAIDs)
  • COX-2 inhibitors


The remaining intestine will need to be inspected by endoscopy as often as every 6 months for the rest of your life. Because the risk of developing other polyps that could grow to become cancer is so high, it is crucial for your doctor to closely monitor your condition. If more polyps arise, further surgery may be required.


There are no current guidelines to prevent FAP.


American Cancer Society

United Ostomy Associations of America, Inc.

Canadian Resources

Colorectal Cancer Association of Canada

Ostomy Canada Society


Familial adenomatous polyposis. EBSCO DynaMed Plus website. Available at: Updated February 28, 2014. Accessed September 6, 2016.

Familial adenomatous polyposis. Genetics Home Reference website. Available at: Updated October 2013. Accessed September 6, 2016.

Jasperson KW, Burt RW. APC-associated polyposis conditions. GeneReviews. Available at: Updated March 27, 2014. Accessed September 6, 2016.