Colon Polyps

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Colon polyp facts

  • Colon polyps are growths on the inner lining of the colon and are very common.
  • Colon polyps are important because they may be, or may become malignant (cancerous). They also are important because based on their size, number, and histology, they can predict which patients are more likely to develop further polyps and colon cancer.
  • Changes in the genetic material of cells lining the colon are the cause of polyp formation.
  • There are different types of colon polyps with differing tendencies to become malignant and abilities to predict the development of more polyps and cancer. It is important to recognize families with members who have familial genetic conditions causing polyps because some of these conditions are associated with a very high incidence of colon cancer.
  • Only a small proportion of polyps cause symptoms or signs. When they do, the symptoms and signs usually are the result of bleeding from the polyp.
  • Colon polyps are diagnosed by endoscopic colonoscopy, virtual colonoscopy, barium enema, and flexible sigmoidoscopy.
  • Colon polyps are treated by endoscopic removal and occasionally by surgery.
  • Follow-up surveillance of patients with colon polyps depends on the presence of a family history of cancer, the number of polyps that are found, the size of the polyps, and the polyps' histology, and can vary between three and ten years.
  • Treatments to prevent colon polyps are being pursued actively.

What are colon polyps?

Colon polyps are growths that occur on the inner lining of the large intestine (colon) and protrude into the colon. They can vary in size from a few millimeters to several centimeters. Polyps form when the genetic material within cells lining the colon changes and becomes abnormal (mutates). Normally, the immature cells lining the colon are programmed to divide (multiply), mature, and then die in a very consistent and timely fashion. However, the genetic changes that occur in the lining cells prevents the cells from maturing, and the cells do not die. This leads to an accumulation of immature, genetically abnormal cells, which eventually results in the formation of polyps. The mutations may occur as a sporadic event after birth or they may be present from before birth.

Picture of colon (colorectal) cancer.
Picture of colon (colorectal) cancer.
Medically Reviewed by a Doctor on 7/10/2014

Patient Comments

Viewers share their comments

Colon Polyps - Describe Your Experience Question: Did you have any of the risk factors for colon polyps at the time of your diagnosis? If so, what were they?
Colon Polyps - Treatments Question: What was the treatment for your colon polyps?
Colon Polyps - Diagnosis Question: Were your colon polyps diagnosed during a colonoscopy? What was the outcome?

Colon Polyps and Colonoscopy

Medical Author Dr. Dennis Lee
Medical Author Dr. Jay W. Marks

Viewer question: I just had a colonoscopy and they found two non-cancerous colon polyps and one non-cancerous lipoma (no previous polyps prior), when should I have my next colonoscopy?

Doctor's response: Lipomas (benign tumors consisting of fat) are benign, that is, they are not cancerous. If the pathologist (the doctor who examines the polyp) is confident that the polyp is a lipoma, no further tests or surveillance will be necessary.

When to perform the next colonoscopy after removal of two non-cancerous, non-lipomatous polyps depends on several issues:

  1. The size of the polyps.
  2. The completeness of the excision.
  3. The histology of the polyps as well as the degree of atypia in the cells that make up the polyps. (Histology refers to the types of cells that make up the polyps as seen under the microscope. Atypia is a term pathologists use to describe cells that appear to be in the process of turning cancerous.)
  4. The quality of the colon preparation and visualization.
  5. The family history of colon cancer.

For example, if one or both polyps were large and not completely excised, your doctor may ask you to have repeat colonoscopy within weeks to months. On the other hand, if the polyps were small (less than 1 cm), completely excised, and did not have significant atypia, the doctor may ask you to have surveillance colonoscopy in five years.

If the colon preparation was poor and there was too much residual stool in the colon for good visualization, the doctor may ask you to have a repeat colonoscopy to make sure there are no more polyps.

Thank you for your question.