Familial adenomatous polyposis is a rare, inherited condition that causes extra tissue (polyps) to form in your large intestine and in the upper part of your small intestine (duodenum). If untreated, the polyps in the large intestine almost always become cancerous by age 40.
Most people with familial adenomatous polyposis eventually need surgery to remove the upper part of the large intestine (colon) to prevent cancer. The polyps in the duodenum can also develop cancer, but they can usually be managed by removing them 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 30 percent of cases, the genetic mutation occurs spontaneously at conception.
The abnormal gene causes hundreds or even thousands of polyps to grow in your colon and rectum, usually starting by your midteens. The polyps are nearly 100 percent certain to develop into colon cancer or rectal cancer by the time you are 40.
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 arise in the duodenum, close to where the bile and pancreas ducts enter it (ampulla). Periampullary polyps also may become cancerous but can often be detected and removed before cancer develops.
- 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, familial adenomatous polyposis 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.
Familial adenomatous polyposis has these variations:
- Attenuated familial adenomatous polyposis causes fewer polyps than classic familial adenomatous polyposis, usually less than 100. You have a high likelihood of developing colon cancer by age 60 if the polyps are not removed.
- Gardner’s syndrome is a form of familial adenomatous polyposis that also causes bony and dental growths.
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
The screening tests for familial adenomatous polyposis and its complications are:
- A flexible tube is inserted into your rectum to inspect the sigmoid — the last two feet of the colon.
- A flexible tube is inserted into your rectum to inspect the entire colon.
- Side-viewing esophagogastroduodenoscopy (EGD). A scope is used to inspect your esophagus, stomach and upper part of the small intestine (duodenum). The doctor may remove a small tissue sample (biopsy) for further study.
- CT or MRI. Imaging the abdomen and pelvis may be used to evaluate desmoid tumors.
If you have a few small polyps, doctor can remove them during your screening exam. Eventually, though, polyps may become too numerous to remove individually. To prevent cancer, we recommend surgery for familial adenomatous polyposis, usually by your late teens or early 20s. Surgery may not be required for attenuated familial adenomatous polyposis.
Surgery doesn’t cure familial adenomatous polyposis. Polyps can continue to form in the remaining or reconstructed parts of your colon, stomach and small intestine. But with careful screening, these polyps usually can be found and removed during colonoscopy before becoming cancerous.
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 speeds your recovery.
The surgeries to treat familial adenomatous polyposis and its complications:
- Ileoanal anastomosis (J pouch) surgery. The colon and rectum are removed while preserving your anus, allowing you to have normal bowel movements.
- Total colectomy. The colon is removed while preserving your rectum and anus, allowing you to have normal bowel movements only if you dont have rectal polyp,
- Continent ileostomy. We may recommend this surgery if your rectum or anus is damaged and J pouch surgery isn’t feasible. In this procedure, your colon is connected to the outside body through an opening (stoma) on the lower abdomen. Bowel movements that would normally have emptied through the rectum are collected in a waste bag that attaches at the stoma..
You are screened regularly and treated for complications of familial adenomatous polyposis that can develop after colorectal surgery.
- Duodenal polyps and periampullary polyps. We may recommend surgery to remove the entire duodenum. The vast majority of people with familial adenomatous polyposis develop duodenal polyps by age 70.
- Desmoid tumors We use a combination of steroid medications, anti-estrogen, chemotherapy and, in some cases, surgery.
- Noncancerous bone tumors. We can remove these tumors for pain relief or cosmetic reasons.