Familial adenomatous polyposis (FAP) is a rare, inherited condition that causes extra tissue (polyps) to form in your large intestine (colon) and rectum. Polyps can also occur in the upper gastrointestinal tract, especially the upper part of your small intestine (duodenum). If untreated, the polyps in the colon and rectum are likely to become cancerous in your 40s.

Most people with familial adenomatous polyposis eventually need surgery to remove the large intestine to prevent cancer. The polyps in the duodenum also can develop cancer, but they can usually be managed by careful monitoring and removing polyps regularly.


Familial adenomatous polyposis is caused by a defect in the adenomatous polyposis coli (APC) gene. Most people inherit the genetic abnormality from a parent. But in about 25 percent of cases, the genetic mutation occurs spontaneously.

The abnormal gene causes hundreds or even thousands of polyps to grow in your colon and rectum, usually starting by your mid-teens. The polyps are nearly 100 percent certain to develop into colon cancer or rectal cancer by the time you're in your 40s.

Familial adenomatous polyposis can cause other complications:

  • Duodenal polyps. These polyps grow in the upper part of your small intestine and may become cancerous. But with careful monitoring, duodenal polyps can often be detected and removed before cancer develops.
  • Periampullary polyps. These polyps occur where the bile and pancreas ducts enter the duodenum (ampulla). Periampullary polyps might become cancerous but can often be detected and removed before cancer develops.
  • Desmoids. These noncancerous masses can arise anywhere in the body but often develop in the stomach area (abdomen). Desmoids can cause serious problems if they grow into nerves or blood vessels or exert pressure on other organs in your body.
  • Other cancers. Rarely, FAP can cause cancer to develop in your thyroid gland, central nervous system, adrenal glands, liver or other organs.
  • Noncancerous skin tumors.
  • Noncancerous bone tumors.
  • Pigment changes in the retina of your eye.
  • Dental abnormalities.
  • Experience. Mayo Clinic specialists have treated thousands of adults and children who have this rare condition.
  • Advanced techniques. At Mayo Clinic, you have access to the latest screening methods, including genetic testing, to determine if you have FAP. Most colorectal surgery at Mayo uses minimally invasive techniques, which can speed your recovery.
  • Compassionate care. If you're at risk of FAP, Mayo Clinic specialists take time to discuss your options with you. Pediatric specialists closely monitor at-risk children.
  • New ideas. Mayo Clinic researchers are investigating new screening methods and surgery options for the disease. You have access to the expertise of Mayo's clinician-researchers.

Mayo Clinic in Rochester, Minn., ranks No. 1 for digestive disorders in the U.S. News & World Report Best Hospitals rankings. Mayo Clinic in Scottsdale, Ariz., and Mayo Clinic in Jacksonville, Fla., are ranked among the Best Hospitals for digestive disorders by U.S. News & World Report.

You're at risk of familial adenomatous polyposis if you have a parent, child, brother or sister with the condition.

If you're at risk, it's important to be screened frequently, starting in childhood. Annual exams can detect the growth of polyps before they become cancerous. At Mayo Clinic, at-risk children who have the defective gene or whose genetic status isn't known are screened every year starting at age 10. At-risk children who don't have the defective gene are screened periodically starting at age 15.

Mayo Clinic specialists use these screening tests for FAP and its complications:

  • Sigmoidoscopy. A flexible tube is inserted into your rectum to inspect the rectum and sigmoid — the last two feet of the colon. At Mayo, sigmoidoscopy is used to screen at-risk children who haven't yet developed polyps.
  • Colonoscopy. A flexible tube is inserted into your rectum to inspect the entire colon. At Mayo, colonoscopy is used after polyps start growing and after age 18, and if attenuated FAP is suspected or already diagnosed.
  • Esophagogastroduodenoscopy (EGD) and side-viewing duodenoscopy. Two types of scopes are used to inspect your esophagus, stomach and upper part of the small intestine (duodenum and ampulla). The doctor may remove a small tissue sample (biopsy) for further study.
  • CT or MRI. Imaging of the abdomen and pelvis may be used, especially to evaluate desmoid tumors.

Genetic testing

A simple blood test can determine if you carry the abnormal gene that causes FAP. Genetic testing may also detect whether you're at risk of complications of FAP.

Mayo Clinic specialists may suggest genetic testing if:

  • You have family members with FAP
  • You have some, but not all, of the signs of FAP

Ruling out FAP spares at-risk children years of screening and emotional distress. For children who do carry the gene, appropriate screening and treatment greatly reduce the risk of cancer.

At Mayo Clinic, genetics counselors discuss the pros and cons of testing with you, including the psychological and medical implications and confidentiality issues. If you choose genetic testing, your counselor and your doctor discuss the results with you.

The Molecular Genetics Laboratory uses the latest techniques to detect specific mutations in the APC gene associated with FAP. If the initial genetic test is negative, Mayo scientists can sequence the MUTYH gene to determine if you have MUTYH-associated polyposis.

Additional tests

Mayo Clinic specialists may recommend thyroid exams and other testing to detect other medical problems that can occur if you have FAP.

If you have a few small polyps, your Mayo Clinic doctor can remove them during your colonoscopy exam. Eventually, though, polyps may become too numerous to remove individually. To prevent cancer, Mayo specialists recommend surgery for familial adenomatous polyposis, usually by your late teens or early 20s. Surgery may not be required for attenuated FAP.

Surgery doesn't cure FAP. Polyps can continue to form in the remaining or reconstructed parts of your colon, stomach and small intestine. But with careful monitoring, these polyps usually can be found and removed during colonoscopy before becoming cancerous.

Minimally invasive colorectal surgery

At Mayo Clinic, most colorectal surgery is done using minimally invasive (laparoscopic) techniques. Laparoscopic surgery is performed through several small incisions that require just a stitch or two to close. Minimally invasive surgery usually shortens your hospital stay and allows you to recover more quickly.

Mayo Clinic specialists use these surgeries to treat familial adenomatous polyposis and its complications:

  • Ileal pouch-anal anastomosis (J-pouch) surgery. The colon and rectum are removed while preserving your anus, allowing you to have normal bowel movements. At Mayo Clinic, J-pouch surgery is the preferred treatment for FAP. J-pouch surgery can affect fertility. Mayo medical geneticists and reproductive gynecologists advise prospective parents about their options.
  • Total colectomy. The colon is removed while preserving your rectum and anus, allowing you to have normal bowel movements. Mayo specialists consider colectomy only if you don't have polyps in your rectum.
  • Continent ileostomy. Mayo specialists may recommend this surgery if your rectum or anus is damaged and J-pouch surgery isn't feasible. In this procedure, your small intestine is connected to the outside body through an opening (stoma) on your abdomen. Bowel movements that would normally have emptied through the rectum are collected in a waste bag that attaches at the stoma. Mayo Clinic has a team of wound and stoma care specialists who provide you with counseling before surgery and education and compassionate support afterward.

Follow-up treatment

At Mayo Clinic, you are screened regularly and treated for complications of familial adenomatous polyposis that can develop after colorectal surgery, including:

  • Duodenal polyps and periampullary polyps. Mayo specialists may recommend surgery in some cases to remove the entire duodenum because these types of polyps can progress to cancer.
  • Desmoid tumors. Mayo specialists use a combination of medications, including nonsteroidal anti-inflammatory drugs, anti-estrogen, chemotherapy and, in some cases, surgery.
  • Noncancerous bone tumors. Mayo surgeons can remove these tumors for pain relief or cosmetic reasons.

Mayo Clinic works with hundreds of insurance companies and is an in-network provider for millions of people. In most cases, Mayo Clinic doesn't require a physician referral. Some insurers require referrals or may have additional requirements for certain medical care. All appointments are prioritized on the basis of medical need.

Specialists in gastroenterology and colon and rectal surgery usually manage care for adults who have familial adenomatous polyposis.

For appointments or more information, call the Central Appointment Office at 800-446-2279 (toll-free) 8 a.m. to 5 p.m. Mountain Standard Time, Monday through Friday or complete an online appointment request form.

Specialists in gastroenterology usually manage care for adults who have familial adenomatous polyposis.

For appointments or more information, call the Central Appointment Office at 904-953-0853 8 a.m. to 5 p.m. Eastern time, Monday through Friday or complete an online appointment request form.

Specialists in gastroenterology, medical genetics, and colon and rectal surgery usually manage care for adults who have familial adenomatous polyposis. Children's care is usually managed through the Children's Center.

For appointments or more information, call the Central Appointment Office at 507-538-3270 7 a.m. to 6 p.m. Central time, Monday through Friday or complete an online appointment request form.

See information on patient services at the three Mayo Clinic locations, including transportation options and lodging.

Mayo Clinic researchers are continually developing improved screening methods and treatments for hereditary polyp disorders and colorectal cancer. Mayo maintains a Colon Cancer Family Registry to help keep you informed of new screening techniques and procedures. Mayo scientists also are working to discover more about the genetic basis of FAP and other hereditary polyp disorders.

See a list of publications by Mayo authors on familial adenomatous polyposis on PubMed, a service of the National Library of Medicine.

Oct. 20, 2015