Some types of polyps (called adenomas) have the potential to become cancerous, while others (hyperplastic or inflammatory polyps) have virtually no chance of becoming cancerous.

When considering risk from colon polyps, the following points should be considered:

  • Polyps are common (they occur in 30 to 50 percent of adults).
  • Not all polyps will become cancer.
  • It takes many years for a polyp to become cancerous.
  • Polyps can be completely and safely removed.

The best course of action when a polyp is found depends upon the number, type, size, and location of the polyp. People who have an adenoma removed will require a follow-up examination as new polyps may develop over time that need to be removed.


Polyps are very common in males and females of all races who live in industrialized countries, suggesting that dietary and environmental factors play a role in their development.


Although the exact causes are not completely understood, lifestyle risk factors include the following:

  • A high-fat diet
  • A diet high in red meat
  • A low-fiber diet
  • Cigarette smoking
  • Obesity

On the other hand, use of aspirin and other nonsteroidal anti-inflammatory drugs and a high-calcium diet may have a protective effect


Polyps and colorectal cancers are uncommon before age 40. Ninety percent of cases occur after age 50, with males somewhat more likely to develop polyps than females; therefore, colon cancer screening is usually recommended starting at age 50 for both sexes.

It takes approximately 10 years for a small polyp to develop into cancer.

Family history and genetics 

Polyps and colon cancer tend to run in families, suggesting that genetic factors are important in their development.

Any history of colon polyps or colon cancer in the family should be discussed with a health care provider, particularly if cancer developed at an early age in the family member, in close biological relatives, or in multiple family members. As a general rule, screening for colon cancer begins at an earlier age in people with a family history of cancer or polyps.

Some rare genetic diseases increase the chances of getting colorectal cancer relatively early in adult life.

  • Familial adenomatous polyposis (FAP) and MUTYH-associated polyposis (MAP) cause multiple colon polyps.
  • Another hereditary nonpolyposis colon cancer, or Lynch syndrome, increases the risk of polyps and colon cancer.


The most common types of polyps are hyperplastic and adenomatous polyps.

Hyperplastic polyps 

Hyperplastic polyps are usually small, located in the end-portion of the colon (the rectum and sigmoid colon), have no potential to become malignant, and are not worrisome.

It is not always possible to distinguish a hyperplastic polyp from an adenomatous polyp based upon appearance during colonoscopy, which means that hyperplastic polyps are often removed or biopsied to allow microscopic examination.

Adenomatous polyps 

Two-thirds of colon polyps are adenomas. Most of these polyps do not develop into cancer, although they have the potential to become cancerous.

Adenomas are classified by their size, general appearance, and specific features as seen under the microscope.

As a general rule, the larger the adenoma, the more likely it is to eventually become a cancer. As a result, large polyps are usually removed completely to prevent cancer and for microscopic examination to guide follow-up testing.

Malignant polyps 

Polyps that contain cancerous cells are known as malignant polyps. The optimal treatment for malignant polyps depends upon the extent of the cancer (when examined with a microscope) and other individual factors.


Polyps usually do not cause symptoms but may be detected during a colon cancer screening examination (such as flexible sigmoidoscopy or colonoscopy) or after a positive screening test for occult blood in the stool.

Colonoscopy is the best way to evaluate the colon for polyps because it allows the clinician to see the entire lining of the colon and remove most polyps that are found (occasionally, large polyps need to be removed during a separate procedure).

The tissue covering a polyp may look the same as normal colon tissue, or there may be tissue changes ranging from subtle color changes to ulceration and bleeding. Some polyps are flat (“sessile”) and others extend out on a stalk (“pedunculated”).

Colonoscopy is the best for the follow-up examination of polyps.


Colorectal cancer is preventable if precancerous polyps (ie, adenomas) are detected and removed before they become malignant (cancerous). Over time, small polyps can change their structure and become cancerous. Polyps are usually removed when they are found on colonoscopy, which eliminates the chance for that polyp to become cancerous.


The medical term for removing polyps is polypectomy. Most polypectomies can be performed through a colonoscope. Small polyps can be removed with an instrument that is inserted through the colonoscope and snips off small pieces of tissue. Larger polyps are usually removed by placing a noose, or snare, around the polyp base and burning through it with electric cautery. The cautery also helps to stop bleeding after the polyp is removed.

Polyp removal is not painful because the lining of the colon does not have the ability to feel pain. In addition, a sedative medication is given before the colonoscopy to prevent pain caused by stretching of the colon. Rarely, a polyp will be too large to remove during colonoscopy, which means that a surgical procedure will be needed at a later time.


Polypectomy is safe although it has a few potential risks and complications. The most common complications are bleeding and perforation (creating a hole in the colon). Fortunately, this occurs infrequently (one in 1000 patients having colonoscopy). Bleeding can usually be controlled during colonoscopy by cauterizing (applying heat) to the bleeding site; surgery is sometimes required for perforation.

Medication use 

Nonsteroidal anti-inflammatory drugs including aspirin, ibuprofen , and naproxen can usually be continued before your colonoscopy. Acetaminophen is safe to take. People who require anticlotting medications such as warfarin should discuss how and when to stop and resume this medication with their clinician.


Follow-up colonoscopy 

The results of the tissue analysis of polyps are discussed with patients when they are available, within a few weeks after the procedure, to decide if and when a follow-up examination is needed.

People with adenomatous polyps have an increased risk of developing more polyps. There is a 25 to 30 percent chance that adenomas will be present on a repeat colonoscopy done three years after the initial polypectomy. Some of these polyps may have been present during the original examination but were too small to detect. Other new polyps may also have developed.

After polyps are removed, repeat colonoscopy is recommended. The exact time interval for follow-up varies depending upon several factors:

  • Microscopic characteristics of the polyp.
  • Number and size of the polyps.
  • Whether it was possible to examine the entire colon.
  • Ability to see the colon during the colonoscopy.

A bowel preparation is needed before colonoscopy to remove all traces of feces (stool). If the bowel preparation was not adequate enough, feces may remain in the colon, making it more difficult to see small- to moderate-size polyps. In such situations, when the colonoscopy was not adequate, it should be repeated to ensure adequate visualization.

Screening saves lives. Persons who undergo regular screening for colon cancer are much less likely to die from colon cancer. Following the screening guidelines can also prevent people from developing colon cancer.

Lifestyle measures 

Guidelines suggest the following:

  • Eat a diet that is low in fat and high in fruits, vegetables, and fiber
  • Maintain a normal body weight
  • Avoid smoking and excessive alcohol use