A colorectal polyp is a growth on the lining of the colon or rectum.A.D.A.M.

Causes, incidence, and risk factors

Polyps of the colon and rectum are usually benign. This means they are not cancerous and do not spread. You may have one or many polyps. They become more common with age.

Common polyp types include:

• Adenomatous polyps - may develop into colon cancer over time
• Hyperplastic polyp - usually do not develop into colon cancer.

Polyps bigger than 1 centimeter have a greater cancer risk than polyps under 1 centimeter. Risk factors include:

• Age
• Family history of colon cancer or polyps
• A type of polyp called villous adenoma

Polyps may also be linked to some inherited disorders, including:

• Familial adenomatous polyposis
• Gardner syndrome
• Juvenile polyposis
• Lynch syndrome (HNPCC)
• Peutz-Jeghers syndrome

Symptoms

There are usually no symptoms. When present, symptoms may include:

• Blood in the stools
• Diarrhea (rare)
• Fatigue caused by losing blood over time

Signs and tests

The health care provider will perform a physical exam. A large polyp may be felt during during a rectal exam.

Most polyps are found with the following tests:

• Barium enema
• Colonoscopy
• Sigmoidoscopy
• Stool test for hidden (occult) blood
• Virtual colonoscopy

Treatment

Colorectal polyps should be removed because some can develop into cancer.  In most cases, the polyps may be removed during a colonoscopy. 

People over age 50 should consider having a colonoscopy or other screening test. Regular colonoscopy helps prevent colon cancer because polyps can be removed before they become cancerous. People with a family history of colon cancer or colon polyps may need to be screened at an earlier age.

For people with adenomatous polyps, new polyps can appear in the future. Follow-up colonoscopy is usually recommended 1 to 10 years later, depending on the:

• Person's age and general health
• Number of polyps
• Size and characteristics of the polyps

Rarely, the health care provider may recommend a colectomy (removing part of the colon) if polyps are very likely to become cancerous.

Expectations (prognosis)

The outlook for people with colorectal polyps is excellent if the polyps are removed. Polyps that are left behind can develop into cancer over time.

Complications

Polyps can cause bleeding. Over time, some polyps can develop into cancers.

Calling your health care provider

Call your health care provider if you have:

• Blood in a bowel movement
• Change in bowel habits

Prevention

 To reduce your risk of developing polyps:

• Eat a diet low in fat and high in fruits, vegetables, and fiber
• Avoid smoking and heavy alcohol intake
• Maintain a normal body weight

Colonoscopy prevents colon cancer by removing polyps before they can become cancer. People over age 50 should consider having a colonoscopy or other screening test. This may reduce the odds of developing colon cancer, or at least help catch it in its most treatable stage. Those with a family history of colon cancer or colon polyps may need to be screened at an earlier age.

Taking aspirin or similar medicines may help reduce your risk for new polpys. However, these medicines can have serious side effects if you take them for a long time. Side effects include bleeding from your stomach or colon and heart disease. Talk with your doctor before taking these medicines.

References

1. Burt RW, Barthel JS, Dunn KB, et al. NCCN clinical practice guidelines in oncology. Colorectal cancer screening. J Natl Compr Canc Netw. 2010 Jan;8(1):8-61. [PubMed: 20064289]
2. Cooper K, Squires H, Carroll C, et al. Chemoprevention of colorectal cancer: systematic review and economic evaluation. Health Technol Assess. 2010 Jun;14(32):1-206. [PubMed: 20594533]

Review Date: 10/8/2012.

Reviewed by: George F. Longstreth, MD, Department of Gastroenterology, Kaiser Permanente Medical Care Program, San Diego, California. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, and Stephanie Slon.