Familial adenomatous polyposis (FAP) is a rare disease that causes hundreds of polyps to form in the colon and rectum.
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FAP is caused by a problem in a certain gene. Polyps start growing mainly during the teenage years. Nearly all people with FAP will have polyps by age 35, and colon or rectal cancer found before age 40.
Your chances for FAP are highest if you have other people in your family with the same disease. But, FAP can also happen without anyone in your family having it. This is caused by new changes in the gene.
You may not notice any symptoms at first. When they appear, FAP may cause:
- Rectal bleeding
- Blood in the stool
- Cramping pain in the belly
- Weight loss
- Feeling tired
The doctor will ask about your symptoms and health history. You may have:
- A physical exam
- An eye exam to look for changes in the back part of your eye
- Tests to check your genes
- Endoscopy—A lighted scope is used to look inside the colon and rectum. Tissue samples are taken at this time and tested for cancer.
FAP is treated with surgery. Since FAP causes so many polyps, they can’t 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.
The 3 main surgical treatments are:
- Colectomy with ileorectal anastomosis (IRA) —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 mimics how the rectum works. It’s then attached to the anal canal. Bowel use will stay.
- Total proctocolectomy with a colostomy —The colon is taken out. This results in the need for a colostomy. A path for solid waste to pass from the body is made through the belly wall. A special bag is needed to collect the waste.
Endoscopy is used to find polyps in the small intestine. This is done through small cuts in the belly. Tubes are placed in the cuts. Tools and lights are inserted into the tubes. Polyps are taken out through the tubes.
Nonsteroidal anti-inflammatory drugs (NSAIDs) shrink the polyps. They can also keep new ones from forming.
There is no way to prevent FAP.
American Cancer Society
United Ostomy Associations of America
Canadian Cancer Society
Ostomy Canada Society
Familial adenomatous polyposis. EBSCO DynaMed website. Available at: http://www.dynamed.com/topics/dmp~AN~T113901/Familial-adenomatous-polyposis. Accessed January 29, 2021.
Familial adenomatous polyposis. Genetics Home Reference website. Available at: https://ghr.nlm.nih.gov/condition/familial-adenomatous-polyposis. Accessed January 29, 2021.
Jasperson KW, Burt RW. APC-associated polyposis conditions. GeneReviews. Available at: http://www.ncbi.nlm.nih.gov/books/NBK1345. Accessed January 29, 2021.
Last reviewed September 2020 by EBSCO Medical Review Board Mohei Abouzied, MD, FACP Last Updated: 1/29/2021