Colon Polyps

What Are They?

Colon polyps are growths of tissue inside the large intestine, also called the colon. Some polyps are mushroom-shaped protrusions on the end of a stalk. Others appear as bumps that lie flat against the intestinal wall.

There are several types of polyps. Most are noncancerous (benign), but one type, the adenomatous polyp, is associated with changes (called mutations) in the DNA of the lining of the colon. These mutations can progress into colon cancer. The larger the polyp, the greater the chance that it contains cancerous cells. For a polyp larger than 1 inch in diameter, there is a 10% chance it is cancerous. Flat polyps are more likely to become cancerous than mushroom-shaped ones.

No one knows exactly what causes these growths, although some people are born with a genetic tendency to develop multiple polyps. Inherited conditions such as familial adenomatous polyposis and Gardner's syndrome can cause hundreds of polyps to grow in the colon and rectum. Without surgery to remove the affected section of the intestine, it is almost certain that at least one of these polyps will turn into cancer by middle age. These two conditions are rare. Most adults are at risk of developing fewer polyps later in life, but they are still at risk of complications.

Symptoms

Many times, people are not aware they have colon polyps because there are no symptoms. Larger growths can bleed, causing blood in the stool. Sometimes bleeding polyps can cause fatigue and other symptoms of anemia (low levels of red blood cells). Occasionally, polyps can grow so large that they block the intestine or, rarely, cause diarrhea.

Diagnosis

Your doctor may use one or more of the following tests to determine whether you have colon polyps:

• Digital rectal exam The doctor inserts a gloved finger into the rectum to check for unusual growths or formations. This can only detect polyps in the rectum, the lower few inches of the bowel.
• Fecal occult blood test A sample of stool is examined for tiny traces of blood, an indication of polyps.
• Sigmoidoscopy A thin, lighted tube fitted with a video camera is inserted into the colon through the rectum, allowing the doctor to examine the area for polyps. Small polyps can be removed through the scope.
• Colonoscopy A longer version of the instrument used in sigmoidoscopy is used to see the entire length of the colon. This is the only test that examines all the areas where cancers may grow. Small polyps can be removed through the scope.
• Barium enema chalky liquid is injected into the colon through the rectum, and then X-ray images are taken of the intestine. Air also may be inserted to expand the colon and allow the area to be seen better.

Expected Duration

If a polyp is not removed, it will continue to grow larger. It usually takes many years for a polyp to grow to a size at which it could become cancerous. About one-third of adenomatous polyps will progress to cancer in three to five years if undetected or ignored.

Prevention

The danger from polyps is that most cases of colon cancer spring from these growths. You can lower your chances of developing cancerous polyps in the following ways:

• Increase your consumption of fruits, vegetables and whole grains.
• Limit your intake of high-fat animal foods.
• Get at least 30 minutes of physical exercise on most days.
• Maintain a healthy weight. Extra fat, especially around the waist alters your metabolism and increases your chances of developing colon and rectal cancer.

In addition, evidence also suggests that doing the following may lower colon cancer risk:

• Take a multivitamin daily. Extra folic acid in multivitamins may be the key.
• Increase your intake of calcium. You can do this by eating or drinking more low-fat dairy products or by taking calcium supplements as advised by your doctor.
• Take aspirin-like drugs. In several studies, people who used aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs) on a regular basis had a 40% to 50% lower chance of developing adenomatous polyps or colorectal cancer. Because of side effects of these drugs, taking them every day just to prevent colon cancer is not advised if your cancer risk is only average.
• Use hormone replacement therapy (HRT). Although the risk of colon cancer may be reduced by 30% to 40% in women who take estrogen after menopause, a woman considering this option should talk to her doctor about this choice because of new research about the long-term consequences of HRT use, including an increased risk of heart attack and stroke.
• Quit smoking. Smoking increases the risk of colon cancer.

Because the risk of colon cancer increases with age, people older than 50 should have a fecal occult blood test and/or a flexible sigmoidoscopy every five years. Alternatively, your doctor may recommend a total colon examination every 10 years. If you have a hereditary condition that causes polyps to overgrow in the large intestine, you should begin frequent examinations at puberty. You also may want to consider complete removal of the colon because there is a high likelihood of developing colon cancer by age 40. If you choose against this option, you should have a sigmoidoscopy or colonoscopy every one to two years.

Treatment

Polyps are removed surgically. Often, the doctor can remove polyps during a colonoscopy. This is done by cutting the polyp from the wall of the colon using an electrical current passed through a wire loop at the end of the colonoscope. Sometimes, open surgery through the abdomen is necessary to remove polyps. For cancerous polyps, surrounding tissue or a section of the colon may be removed as well.

When To Call A Professional

You should call immediately for advice if you develop rectal bleeding. You also should see your doctor regularly for routine colon examinations after age 50. People with a family history of colon cancer, familial adenomatous polyposis, or Gardner's syndrome should begin screening earlier.

Prognosis

Although it is estimated that 30% of middle-aged and older people have colon polyps, less than 1% of all polyps ever become cancerous. For people who catch and treat colon cancer early, the 5-year survival rate is 90%. If the cancer has reached the lymph nodes, the chance of survival drops to 65%. When the cancer has spread to distant parts of the body, like the liver or bones, the likelihood of living more than 5 years drops to 8%.

Additional Info

American Cancer Society (ACS)

1599 Clifton Road, NE

Atlanta, GA 30329-4251

Toll-Free: (800) 227-2345

http://www.cancer.org/

National Cancer Institute (NCI)

U.S. National Institutes of Health

Public Inquiries Office

Building 31, Room 10A03

31 Center Drive, MSC 8322

Bethesda, MD 20892-2580

Phone: (301) 435-3848

Toll-Free: (800) 422-6237

TTY: (800) 332-8615

E-Mail: cancergovstaff@mail.nih.gov

http://www.nci.nih.gov/