Topic Overview

What are colon polyps?

Colon polyps are growths in your large intestine (colon). The cause of most colon polyps is not known, but they are common in adults.

Most colon polyps are not cancer. But some growths can turn into colon cancer. If a colon polyp is the kind that can turn into cancer, it usually takes many years for that to happen.

People over 50 are more likely than younger people to get colon cancer. So experts recommend that everyone age 50 or older have a screening test to look for colon polyps. Finding and removing colon polyps can prevent colon cancer.

What are the symptoms?

You can have colon polyps and not know it because they usually don't cause symptoms. They are usually found during routine screening tests for colon cancer. A screening test looks for signs of a disease when there are no symptoms.

If polyps get large, they can cause symptoms. You may have bleeding from your rectum or a change in your bowel habits. A change in bowel habits includes diarrhea, constipation, going to the bathroom more often or less often than usual, or a change in the way your stool looks.

How are colon polyps diagnosed?

Most polyps are found during screening tests for colon cancer. Screening is advised if you are age 50 or older or you have a higher risk for the disease. The four screening tests for colon cancer are:

• Colonoscopy. In this test, the doctor inserts a small viewing tube all the way into your colon and looks for polyps. The doctor can also take out any polyps he or she finds.
• Flexible sigmoidoscopy. This test is like a colonoscopy, except that the viewing tube is shorter so the doctor can only look at the last part of your colon.
• Fecal occult blood test. This test checks for blood in your stool. You place a small sample of stool on a special card, pad, or wipe in a kit that your doctor gives you. The sample is sent to a lab and is tested to see if it contains blood.
• Barium enema. To make it show up on an X-ray, your colon is filled with a white liquid (barium). The liquid blocks the X-rays, so your colon shows up clearly in the picture.

Doctors often recommend colonoscopy because it lets them look at the whole colon and remove any polyps they find. If polyps are found during another type of test, you may still need colonoscopy so the doctor can remove the polyps.

What increases my risk of getting colon polyps?

You are more likely to have colon polyps if:

• You are over 50.
• Colon polyps run in your family.
• You inherited a certain gene that causes you to develop polyps. People with this gene are much more likely than others to get the kind of polyps that turn into colon cancer.

How are they treated?

Doctors usually remove colon polyps because some of them can turn into colon cancer. Most polyps are removed during a colonoscopy. You may need to have surgery if you have a large polyp.

Colon polyps can grow back. If you have had polyps removed, it is important to have follow-up testing to look for more polyps. Talk to your doctor about how often you need to be tested.

Frequently Asked Questions

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Symptoms

Colon polyps usually do not cause symptoms unless they are larger than 1 cm (0.4 in.) or they are cancerous. The most common symptom is rectal bleeding. Sometimes the bleeding may not be obvious (occult) and may only be discovered after doing a screening test for blood in the stool called a fecal occult blood test (FOBT).

Colon polyps usually do not cause pain or a change in bowel habits unless they are large and are blocking part of the colon. These symptoms are rare because polyps usually are discovered and removed before they become large enough to cause problems.

Once cancer develops, additional symptoms also may occur, such as changes in bowel habits and significant weight loss.

Exams and Tests

Unless colon polyps are large and cause bleeding or pain, the only way to know if you have polyps is to have one or more tests that explore the inside surface of your colon.

Several tests can be used to detect colon polyps. Two of these exams, flexible sigmoidoscopy and colonoscopy, also can be used to collect tissue samples (called a biopsy) or to remove colon polyps. All the tests may be used to screen for colon polyps and colon cancer and as follow-up tests after colon polyps have been removed. These tests include:

• Fecal occult blood test (FOBT). A fecal occult blood test (FOBT) is done to look for microscopic amounts of blood in stool. FOBT is a simple, low-cost screening tool for colon polyps or colon cancer. FOBT has been shown in studies to reduce the number of deaths from colon cancer.¹ By itself, an FOBT is not evidence of colon polyps or colon cancer, and a negative FOBT (no blood found) does not mean that you do not have colorectal cancer. If a fecal occult blood test is positive for blood in the stool, it is important to have a colonoscopy to help your doctor find the source of the blood and remove polyps if they are found.
• Flexible sigmoidoscopy.Flexible sigmoidoscopy allows the doctor to look at the lower third of the colon. During a sigmoidoscopy exam, samples of any growths can be collected (biopsied), and precancerous and cancerous growths can sometimes be removed. Although a sigmoidoscopy does not cover the entire colon, a study has found that when combined with an FOBT, it can detect about 76% of advanced colon polyps or cancers.²
• Colonoscopy. This screening method allows a doctor to inspect the entire colon for polyps and cancer. During a colonoscopy, samples of any growths can be collected (biopsied), and precancerous and cancerous growths sometimes can be removed. Expert groups recommend having the test every 10 years beginning at age 50 for people who are at average risk of colon cancer or whenever another screening test is positive for possible colon polyps or cancer. Screening may begin earlier and be more frequent in people at higher risk for colon polyps and colon cancer.³
• Double-contrast barium enema (DCBE). This exam, also known as a lower gastrointestinal (GI) exam, is an X-ray of the large intestine. A double-contrast barium enema can be used to screen for colon cancer because it can detect polyps in the entire colon. A DCBE can more accurately detect large polyps and cancer than a fecal occult blood test combined with flexible sigmoidoscopy. However, a DCBE is not as accurate as a colonoscopy. DCBE also may miss smaller polyps, may incorrectly identify stool as a polyp, and does not allow the doctor to obtain a biopsy or remove polyps.

Research is being done on other methods to detect colon cancer. One method is virtual colonoscopy, which is a noninvasive screening method that uses a CT scan to view the colon. Another method is genetic testing of stool samples, which is a test that checks for changes to the cells in the colon. Certain kinds of changes in cell DNA happen when you have cancer.

Screening for colon cancer

Screening for colon cancer with a single test or a combination of tests reduces your chance of having complications and dying from colon cancer. Expert groups recommend routine colon cancer screening for all people older than 50 who are at average risk for colon cancer. These are people who have no family history of colon polyps or colon cancer, have not had colon polyps or colon cancer, and are not having symptoms of colon cancer.

If you are older than 50, screening may lower your risk of developing colon cancer. Screening options include:

• Test for blood in the stool (fecal occult blood test, or FOBT) every year.
• Flexible sigmoidoscopy every 5 years.
• Fecal occult blood test every year and a flexible sigmoidoscopy every 5 years.
• Double-contrast barium enema (DCBE) every 5 years.
• Colonoscopy every 10 years.

The method of screening that you have depends on your personal preferences, your doctor’s preferences, and what the clinic or office you go to is able to do.

Should I have a sigmoidoscopy or a colonoscopy to screen for colorectal cancer?

If you are at increased risk of developing colon cancer, you may need to begin screening earlier or to be tested more often.

If you have a family history of colon cancer, you should begin having tests for the disease either at age 40 or when you are 10 years younger than the age of the youngest case in your immediate family.

If you have a family history of familial adenomatous polyposis (FAP), you should begin screening exams beginning at age 10 or 12.³

If you have a family history of hereditary nonpolyposis colon cancer (HNPCC), you should have a colonoscopy every 1 to 2 years starting at age 20 to 25, or 10 years younger than the age at which the youngest family member who has colorectal cancer was diagnosed, whichever comes first.³

The decisions about when to start and stop screening for colon cancer should be made with your doctor. These decisions will depend on how old you are, your family history, any health problems you may have, and the benefits you can expect from regular screening.

Follow-up testing

If a biopsy of polyps obtained during screening reveals only hyperplastic polyps of any size, routine follow-up screening is all that is needed. These polyps do not become cancerous.

Most doctors agree that if you have had one or more adenomatous polyps removed, you probably need regular follow-up colonoscopy exams every few years.³ This type of polyp is more likely to turn into cancer, but that risk is still very low. How often you need a colonoscopy may depend on the number and size of the polyps, your age, your health, and other risk factors that you may have for polyps. Talk with your doctor about the follow-up testing schedule that is right for you.

Treatment Overview

Most colon polyps do not cause any problems, but a sample of polyp tissue (called a biopsy) can be removed during screening if you have a flexible sigmoidoscopy or colonoscopy. The tissue is examined to determine if it is the kind of tissue that could become cancer.

Initial treatment

If adenomatous polyps are found during an exam with flexible sigmoidoscopy, a colonoscopy will be done to look for and remove any polyps in the rest of the colon.

The bigger a colon polyp is, especially if it is larger than 1 cm (0.4 in.), the more likely it is that the polyp will be adenomatous or contain cancer cells and need to be removed.

In some cases, very small polyps [5 mm (0.2 in.) or less] may not be removed. Some studies have concluded that even if they contain adenomatous tissue, these polyps take so many years to grow that they pose little risk of cancer, except in people who have inherited (familial) polyp syndromes.⁴

Most colon polyps are not likely to develop into cancer. If only hyperplastic polyps are found during your flexible sigmoidoscopy, you usually do not need to have a colonoscopy. These polyps do not become cancerous. In this case you can continue your regular screenings, unless you are at an increased risk for colon cancer because of a family history of colon cancer or an inherited polyp syndrome.

Risks of removing polyps during colonoscopy

Complications from colonoscopy are rare. There is a slight risk of:

• Puncturing the colon (less than 1 in 1,000) or causing severe bleeding by damaging the wall of the colon (less than 3 in 1,000). One study found that the risk of perforation from colonoscopy has declined in recent years.⁵
• Bleeding caused by removing a polyp.
• Complications from sedatives given during the procedure.

Ongoing treatment

Regular screenings for colon polyps are the best way to prevent polyps from developing into colon cancer. All men and women ages 50 and older should have either:

• A fecal occult blood test every year or
• A flexible sigmoidoscopy every 5 years or
• A fecal occult blood test every year and a flexible sigmoidoscopy every 5 years or
• A double-contrast barium enema every 5 years or
• A colonoscopy every 10 years.

Most colon polyps can be identified and removed during a colonoscopy. Colon polyps can be identified during a flexible sigmoidoscopy, but you will most likely need to have a colonoscopy to remove the polyps.

If you have had one or more adenomatous polyps removed, you probably need regular follow-up colonoscopy exams every 3 to 5 years. Talk with your doctor about the follow-up schedule that he or she recommends for you.

Treatment if the condition gets worse

Surgery is sometimes needed for large colon polyps that have a broad area of attachment (sessile polyps) to the colon wall. These large polyps often cannot be removed safely during a colonoscopy and may be more likely to develop into cancer.

If cancer is found when the colon polyps are examined, you will begin treatment for colorectal cancer. For more information, see the topic Colorectal Cancer.

Home Treatment

No home treatment is done for colon polyps. See the Treatment Overview section of this topic for more information.

However, you can take action that may prevent colon polyps from developing:⁶

• Eat a low-fat, high-fiber diet.
• Maintain a healthy body weight.
• Quit smoking.
• Use alcohol in moderation. Moderate alcohol use usually is defined as one alcoholic beverage per day for women and two for men.
• Take calcium supplements. Taking 3 g of calcium carbonate each day may keep polyps from coming back after they are removed.

Experts are not yet certain that these approaches prevent colon polyps or colorectal cancer.

These self-care methods should not be a substitute for regular colorectal screening, especially if you are older than 50 or are at increased risk of developing colon polyps or colon cancer. While these approaches may decrease your risk of developing colon polyps, they will not prevent you from ever developing colon polyps.

Other Places To Get Help

Organizations

Related Information

• Colorectal Cancer
• Early Disease Detection

References

Citations

1. Mandel JS, et al. (2000). The effect of fecal-occult blood screening on the incidence of colorectal cancer. New England Journal of Medicine, 343(22): 1603–1607.

2. Lieberman DA, Weiss DG (2001). One-time screening for colorectal cancer with combined fecal occult-blood testing and examination of the distal colon. New England Journal of Medicine, 345(8): 555–560.

3. Winawer S, et al. (2003). Colorectal cancer screening and surveillance: Clinical guidelines and rationale—Update based on new evidence. Gastroenterology, 124(2): 544–560.

4. Itzkowitz SH, Rochester J (2006). Colonic polyps and polyposis syndromes. In M Feldman et al., eds., Sleisenger and Fordtran's Gastrointestinal and Liver Disease, 8th ed., vol. 2, pp. 2713–2757. Philadelphia: Saunders/Elsevier.

5. Gatto NM, et al. (2003). Risk of perforation after colonoscopy and sigmoidoscopy: A population-based study. Journal of the National Cancer Institute, 95(3): 230–236.

6. Bond JH, et al. (2000). Polyp guidelines: Diagnosis, treatment, and surveillance for patients with colorectal polyps. American Journal of Gastroenterology, 95(11): 3053–3063.

Other Works Consulted

• Bresalier RS (2006). Malignant neoplasms of the large intestine. In M Feldman et al., eds., Sleisenger and Fordtran's Gastrointestinal and Liver Disease, 8th ed., vol. 2, pp. 2759–2810. Philadelphia: Saunders/Elsevier.

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