|What Are Colon Polyps?
A colon polyp is a small growth on the surface of the colon (also known as the large intestine). You may have one or more polyps at a time and they can be raised or flat. Although most colon polyps are harmless, they can become cancerous over a period of years if not removed. Flat polyps are harder to see than raised ones and are more likely to be cancerous.
What Are The Symptoms?
Very often they cause no symptoms. Most are only diagnosed during a routine screening of the bowels (colonoscopy). Sometimes, however you may have signs such as:
Rectal bleeding: You may notice some bright red blood on your toilet paper after a bowel movement. This can be a sign of colon polyps and colon cancer, but it can also indicate far less serious conditions such as minor tears (fissures) or hemorrhoids.
Blood in stool: There is red streaks of blood in your stool or your stool appears black. Still, it does not always indicate a problem - some iron supplements and anti-diarrhea meds can turn stools black.
Change in bowel habit: Diarrhea, constipation or narrowing of the stool, any change of bowel habit that lasts longer than a week can indicate the presence of a large polyp. If it partially obstructs the bowel it can lead to a crampy tummy pain, nausea and constipation.
When Should I See A Doctor?
Talk to your doctor if you have the following symptoms:
• Tummy pain.
• Bloody stools.
• A change in bowel habits that last longer than a week.
You Should Screen For Colon Polyps If:
• You are aged over 50.
• There is a history of colon cancer in the family. High risk people should begin screening much earlier than 50.
See our list of recommended screenings for women at different times of life.
What Causes Colon Polyps?
The colon is the last part of the digestive tract called the large intestine. It ends at the anus. Its main role is to absorb water and minerals from stool before it is passed out of the body. It stores the waste until you are ready to have a bowel movement. The majority of colon polyps are not cancerous but like most cancers they are the result of abnormal cell growth. Just as scientists are uncertain as to the causes of cancer, the cause of colon polyps has not been identified.
Types Of Colon Polyps
There are 3 main types, these are:
Adenomatous: (picture above). Nearly 70 percent of colon polyps are adenomatous. Only a tiny percentage of this type become cancerous - BUT - nearly all polyps that become cancerous are adenomatous.
Hyperplastic: These make up most of the remaining polyps. Usually less than 5mm in size it is not uncommon to have up to 100 in the colon tract. They are rarely malignant.
Inflammatory: These can occur after a bout of Crohn's disease or ulcerative colitis. An internal view (picture above) shows an inflamed and lumpy colon. Although these polyps can become cancerous, having either ulcerative colitis or Crohn's disease also increases your overall risk of colon cancer.
How Are They Diagnosed?
Screening plays a major role in the detection of colon polyps, and the same tests that are used for screening are used in the diagnosis procedure. Several screening methods exist, each has its own pros and cons:
Colonoscopy: You will be given a mild sedative to make you more comfortable. In a colonoscopy the doctor inserts a long thin flexible tube, which has a video camera attached to it, into the rectum and up into the colon. The images are shown on a TV screen. The tube also has a cutting tool attached to it, so any polyps found can be removed during the procedure. Tissue samples from the surrounding area may also be taken for biopsy to check for colorectal cancer. There is a risk of perforation of the colon wall with this procedure (particularly if polyps are removed).
Virtual Colonoscopy: Also called a computerized tomographic colonography (CTC), this test takes an X-ray of the colon. The machine will rotate to take images of your colon from every angle without entering your body. It is a more expensive procedure but of course it is much less invasive and requires no sedation. The downside is that it does not allow for polyp removal if one is found or for taking a tissue sample for biopsy. A regular colonoscopy will still be required.
Sigmoidoscopy: Similar to a colonoscopy, in this test the doctor inserts a thin lighted tube into the rectum and the sigmoid (that is, the last 2 feet of your colon which ends in the anus). Nearly 50 percent of colon cancers are found in this area. If a polyp is found a colonoscopy will still be required to check the entire colon for others. The main benefit is that there is less risk of perforating the colon with this test than with colonoscopy.
Barium Enema: This procedure is one of the least effective diagnostic tools. A contrast solution containing barium is placed into your rectum. It coats the lining of the bowel and an X-ray is taken. Your intestine will look white and polyps are darker. It is not as detailed as other screening methods, so polyps can be missed. Also, a colonoscopy will still be required to remove any polyps found.
Stool Test: You provide a stool sample which is checked for signs of cancer (it isn't much good for testing for polyps). Your doctor may even give you a test kit to perform the test yourself at home. There are two kits: fecal occult blood test (FOBT) and fecal immunohistochemical test (FIT).
Stool DNA Testing: This is a newer test for screening for colon cancer. It can detect cancer cells that have shed into your stool. Genetic Testing: If there is a history of colorectal cancer in the family you may be a candidate for genetic testing to assess your risks. However, the results can be ambiguous - just because you test positive for a defective gene does not mean you will develop cancer. It is however good reason to start screening regularly.
How Are They Treated?
All polyps discovered in a screening should be removed and checked by a pathologist for cancer. The vast majority can be removed by during colonoscopy or sigmoidoscopy by snaring them with a looped wire which cuts them at the stalk and cauterizes them to prevent bleeding. Smaller polyps may just be burned or cauterized with an electrical current. Both procedures, when it involves polyp removal, are known as a polypectomy.
When surgery is necessary: If a polyp is too large to be snared or cannot be safely reached, laparoscopic (keyhole) surgery may be required. Several small incisions are made in the tummy and an instrument with a camera and cutting tool attached is inserted. Some specialized centers are offering a newer technique called endoscopic mucosal resection (EMR). This involves inserting a liquid like saline under the polyp so that it is raised and easier to isolate from surrounding tissue. This makes it easier to remove larger polyps by colonoscopy, thus removing the need for surgery.
While anyone can develop colon polyps, your risk is higher if you:
• Are aged over 50.
• Or someone in the family has had polyps or colon cancer before.
• Had ovarian cancer or endometrial cancer before the age of 50.
• Have ongoing inflammatory diseases of the colon, such as ulcerative colitis and Crohn's disease.
• Drink excessively, especially beer.
• Are overweight or obese. This raises your risks for all types of cancer.
• Are black or Ashkenazi Jew of Eastern European descent - raises your risk of colon cancer.
• Inherited genetic mutations associated with colon cancer.
Can Colon Polyps Be Prevented?
There is no sure way of preventing polyps, but you may lower your risk factor by:
• Eating a healthy diet with fruit and vegetables and less fatty foods.
• Not smoking.
• Drinking alcohol in moderation.
• Taking regular exercise.
• Maintaining a healthy body weight.
• Eating more calcium. Foods rich in calcium include dairy products and broccoli.
• Taking a low dose of aspirin daily. Talk to your doctor before doing this because it can increase your risk of gastrointestinal bleeding.
American College of Gastroenterology
P.O. Box 342260
American Gastroenterological Association
4930 Del Ray Avenue
Bethesda, MD 20814
American Society for Gastrointestinal Endoscopy
1520 Kensington Road, Suite 202
Oak Brook, IL 60523
Phone: 1–866–353–ASGE (2743) or 630–573–0600