POLYPS OF COLON

Polyps



Polyps are small growths that develop along the lining of  the colon.  They often look like small nubbins, similar in appearance to the bumps on the outside of a squash.  Some have a stalk or pedicle, giving them a mushroom look.  Others are flat, like a small patch of miniature shag carpet.

Polyps are important because it is now known that most colon cancers arise from benign (non-cancerous) polyps.  If we can identify patients who have colon polyps without cancer, we can probably prevent those patients from getting cancer, by removing their polyps.

Most polyps can be removed without surgery. The procedure is called colonoscopy, and it involves passing a long flexible scope up into the colon through the anus.  The polyps can be seen, snared with a wire loop through the scope, and removed for analysis.  Some polyps may be too large or too flat (the "shag carpet" type) to be removed through the scope.  Is such cases, surgery may be recommended to remove the polyp.

Colon cancer

Colon and rectal cancer are very common, ranking just below lung and breast cancer in frequency.  Symptoms of colon or rectal cancer are often minimal, but may include rectal bleeding, abdominal pain, or an alteration in your usual bowel habits (new onset of diarrhea or constipation, a change in the thickness or "caliber:" of the stool, black or burgundy stools).

With the advent of colonoscopy, there has been much interest in screening for colon cancer.  It is strongly recommended that patients over age 50 be checked annually for any hidden blood in the stool. For patients with a family history of colon cancer, and in African-American patients, screening should begin even earlier, at age 45.  Total colonoscopy or a flexible sigmoidoscopy  is also recommended to look for any polyps.  Finding polyps before they have the opportunity to develop into cancer is currently the best method available to decrease the incidence of colon and rectal cancer.  If no polyps are seen, the screening colonoscopy is recommended every 10 years;  If flexible sigmoidoscopy is used for screening, it should be repeated every 5 years.

Types of polyp

Metaplastic polyps versus adenomatous polyps

The most common sort of polyp is a metaplastic polyp (in which cells change from one normal type to another). These usually do not grow much more than 5mm in diameter and have almost no risk of becoming malignant (cancerous). These polyps can be very similar in appearance to adenomatous polyps, the next most common type, which do have the potential to become malignant.

About 50 per cent of people aged 60 will have at least one adenomatous polyp of 1cm diameter or greater. Familial polyposis coli (familial adenomatous polyposis or FAP ) involves multiple adenomatous polyps, often in their hundreds. This condition carries a very high risk of colon cancer.

Other rarer types of polyps include:

• Juvenile polyps:
• these are usually solitary polyps called hamartomas that affect 1 to 2 per cent of older children or adolescents. A single polyp carries no significant cancer risk but when these polyps are inherited and usually multiple (about one third of patients), the colon cancer risk is about 10 per cent. In this case, regular surveillance after excision (cutting out) of all polyps is required.
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• Peutz-Jeghers polyps:
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• found in Peutz-Jeghers syndrome, in association with freckling of the lips, are also of the hamartomatous type. These usually present in early adult life and carry a low but definite risk of malignancy, probably around five per cent per polyp, so they need excision. The number of polyps per individual is very variable and ranges, from as few as one or two to as many as 20 or more. Peutz-Jeghers polyps can also occur in the small intestine and can then be difficult to diagnose because they are beyond the reach of conventional fibre-optic endoscopes (internal telescope instruments). Such polyps tend to present with symptoms of obstruction (bowel blockage) or abdominal pain. Diagnosis is usually made with barium X-rays (taken after the patient swallows barium liquid to show up the inside of the intestine). Treatment will usually be an operation that opens up the abdomen.
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• Inflammatory pseudopolyps: 
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• can occur as a complication of ulcerative colitis or Crohn's disease of the colon. They are completely harmless and carry no risk of cancer but they can be confused with adenomatous polyps on examination.
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• Cronkhite-Canada syndrome: 
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• an exceptionally rare condition, involves multiple colon polyps, hyperpigmentation (darkening of the skin) and nail atrophy (wasting away). The syndrome is not inherited and affects middle-aged or older individuals. It is linked with malabsorption and has been reported to respond to vitamin E therapy.

What causes polyps?

Most polyps, with the exception of the inflammatory pseudopolyps, result from some form of genetic (DNA) mutation in one of the colon lining cells. Fortunately, several, probably at least five, mutations are needed in the same cell before cancer occurs and most benign polyps probably only have one gene mutated. DNA damage occurs surprisingly often.

Even in a healthy adult's colon, about 10 per cent of the lining cells, on average, contain major abnormalities of the chromosomes (packages of DNA that contain many genes). Fortunately, almost all these cells seem to undergo a form of programmed death called apoptosis, and then fall off harmlessly into the bowel lumen (cavity).

Adenomatous polyps, even those from individuals who do not have familial polyposis, commonly contain mutations that stop the gene working in both copies of the adenomatous polyposis coli (APC) gene, the gene that is mutated in familial polyposis coli.

Who gets colon polyps?

Anyone can get colon polyps, but certain people are more likely to get them than others. You may have a greater chance of getting polyps if

• you're 50 years of age or older
• you've had polyps before
• someone in your family has had polyps
• someone in your family has had cancer of the large intestine, also called colon cancer
• you've had uterine or ovarian cancer before age 50

You may also be more likely to get colon polyps if you

• eat a lot of fatty foods
• smoke
• drink alcohol
• don't exercise
• weigh too much

What are the symptoms of colon polyps?

Most people with colon polyps do not have symptoms. Often, people don't know they have one until the doctor finds it during a regular checkup or while testing for something else.

But some people do have symptoms, such as

• bleeding from the anus. The anus is the opening at the end of the digestive tract where stool leaves the body. You might notice blood on your underwear or on toilet paper after you've had a bowel movement.
• constipation or diarrhea that lasts more than a week.
• blood in the stool. Blood can make stool look black, or it can show up as red streaks in the stool.

How does the doctor test for colon polyps?

The doctor can use one or more tests to check for colon polyps.

• Barium enema. The doctor puts a liquid called barium into your rectum before taking x rays of your large intestine. Barium makes your intestine look white in the pictures. Polyps are dark, so they're easy to see.
• Sigmoidoscopy. With this test, the doctor puts a thin, flexible tube into your rectum. The tube is called a sigmoidoscope, and it has a light in it. The doctor uses the sigmoidoscope to look at the last third of your large intestine.
• Colonoscopy. The doctor will give you medicine to sedate you during the colonoscopy. This test is like the sigmoidoscopy, but the doctor looks at the entire large intestine with a long, flexible tube with a camera that shows images on a TV screen. The tube has a tool that can remove polyps. The doctor usually removes polyps during colonoscopy.
• Computerized tomography (CT) scan. With this test, also called virtualcolonoscopy, the doctor puts a thin, flexible tube into your rectum. A machine using x rays and computers creates pictures of the large intestine that can be seen on a screen.
  The CT scan takes less time than a colonoscopy because polyps are not removed during the test. If the CT scan shows polyps, you will need a colonoscopy so they can be removed.
• Stool test. The doctor will ask you to bring a stool sample in a special cup. The stool is tested in the laboratory for signs of cancer, such as DNA changes or blood.

What is the treatment?

Polypectomy

Most polyps can be removed during colonoscopy while the patient is sedated. This is done by passing a wire snare down the colonoscope, looping and tightening the snare around the stalk of the polyp, then passing an electric current through the wire. This coagulates the blood vessels and then cuts through the stalk. The polyp is then usually sent to the pathology laboratory for microscopic examination.

The polypectomy is painless because the colon nerves are only sensitive to stretching. Polypectomy is very safe but carries a risk of perforation (going through the bowel wall) in about one case in 300 and bleeding in one case per 100. Bleeding usually stops by itself and only rarely needs treatment with blood transfusion.

Surgery

Occasionally, a polyp is too large to be removed endoscopically, usually when the diameter is more than about 4cm and, particularly, if the base of the polyp is broad with no well-defined stalk. In these cases, endoscopic removal can carry an unacceptably high risk of bleeding or perforation. Such polyps are also more likely to already contain cancer and removal by surgery that opens up the abdomen can be the safest option to ensure cure.

What follow up is needed after polypectomy?

A polyp that has been completely cut out will not itself recur but some people have a tendency to form multiple polyps so new polyps can grow after polypectomy. If an individual has four or more polyps, or one polyp of more than 1cm diameter or a polyp with severely abnormal cells (dysplasia) seen under the microscope, the risk of polyp or cancer occurrence is sufficient to warrant regular surveillance with colonoscopy. This is usually repeated every five or six years.

Prevention

You can greatly reduce your risk of colon polyps and colorectal cancer by having regular screenings and by making certain changes in your diet and lifestyle. The following suggestions may help lower your risk of colon polyps and colon cancer:

• Pay attention to calcium. Calcium can significantly protect against colon polyps and cancers, even if you've had them before. Good food sources of calcium include skim or low-fat milk and other dairy products, broccoli, kale and canned salmon with the bones. Vitamin D, which aids in the absorption of calcium, also appears to help reduce the risk of colorectal cancer. You get vitamin D from foods such as vitamin D-fortified milk products, liver, egg yolks and fish. Sunlight also converts a chemical in your skin into a usable form of the vitamin. If you don't drink milk or you avoid the sun, you may want to consider taking both a vitamin D and a calcium supplement.
• Include plenty of fruits, vegetables and whole grains in your diet. These foods are high in fiber, which may cut your risk of developing colon polyps. Fruits and vegetables also contain antioxidants, which may help prevent cancer.It is recommended eating at least five servings of fruits and vegetables every day.
• Watch your fat intake. Certain types of fat can increase your risk of colon cancer. It's important to limit saturated fats from red meat as well as processed meat such as hot dogs, sausage or brats. Limit saturated fat to no more than 10 percent of your daily calorie intake.
• Limit alcohol consumption. Consuming moderate to heavy amounts of alcohol — more than one drink a day for women and two for men — may increase your risk of colon polyps and cancer. A drink is considered to be 4 to 5 ounces (118 to 148 milliliters) of wine, 12 ounces (355 milliliters) of beer, or 1.5 ounces (44 milliliters) of 80-proof liquor.
• Don't use tobacco products. Smoking and other forms of tobacco use can increase your risk of colon cancer and a wide range of other diseases. Talk to your doctor about ways to quit that might work for you.
• Stay physically active and maintain a healthy body weight.Controlling your weight alone can reduce your risk of colorectal cancer. And staying physically active may significantly cut your colon cancer risk.It is recommended at least 30 minutes of physical activity five or more days a week. Forty-five minutes or more is even better. If you're overweight, lose weight until you're at a healthy level and maintain it.
• Talk to your doctor about aspirin. Regular aspirin use may reduce your risk of polyps. But, aspirin use can increase your risk of gastrointestinal bleeding. So check with your doctor before starting any aspirin regimen.
• Talk to your doctor about hormone therapy (HT). If you're a woman past menopause, hormone therapy may reduce your risk of colorectal cancer. But not all effects of HT are positive. Taking HT as a combination therapy — estrogen plus progestin — can increase your risk of breast cancer, dementia, heart disease, stroke and blood clots, so it's not usually used for preventing colon polyps. Discuss your options with your doctor. Together you can decide what's best for you.
• If you're at high risk, consider your options. If you're at risk of familial adenomatous polyposis (FAP) because of a family history of the disease, consider having genetic counseling. And if you've been diagnosed with FAP, start having regular colonoscopy tests in your early teens and discuss your options with your doctor. Your doctor may recommend having surgery to remove your entire colon. Doctors recommend that people at risk of Lynch syndrome begin having regular colonoscopies around age 20. If you have a genetic cancer syndrome, make sure your family members are tested.

Large, rectal polyps can sometimes be removed through the anus under general anaesthetic without the need to cut open the abdomen.

Points to Remember

• A colon polyp is a growth on the surface of the colon, also called the large intestine.
• Colon polyps can be raised or flat.
• Some colon polyps are benign, which means they are not cancer.
• Some types of polyps may already be cancer or can become cancer. Flat polyps can be smaller and harder to see and are more likely to be cancer than raised polyps.
• Most people with colon polyps do not have symptoms.
• Symptoms may include constipation or diarrhea for more than a week or blood on your underwear, on toilet paper, or in your stool.
• Doctors remove most colon polyps and test them for cancer.
• Talk with your doctor about getting tested for colon polyps if you're 50 years of age or older, or earlier if you have symptoms or someone in your family has had polyps or colon cancer.