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Erin N. Marcus, M.D. Headshot

Colorectal Cancer Screening: Know Your Options

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Stanley Thornton, Colorectal Cancer Screening Advocate
(Courtesy, Stanley Thornton)

It's exceedingly uncommon for a healthy middle-aged man to walk into his doctor's office and demand a colonoscopy. But even though he lacked a family history, Stanley Thornton, an African-American engineer who was then in his mid-40's, wouldn't take no for an answer.

"I was concerned that African-Americans do get colorectal cancer earlier, and I said, 'hey, let me lead by example,'" he said recently. "We argued about it for a month or two. He felt I should wait until I was 50."

Eventually, Mr. Thornton got the test, and was found to be clear of cancer. He describes the "prep" -- the liquid he had to drink to clean out his intestines the night before the procedure -- as "not the nicest thing in the world," and said he was apprehensive as his wife drove him to his appointment since he didn't know what to expect. But he said the only uncomfortable part of the test, in which a doctor put a thin tube up his rectum in order to inspect his large intestine, was when the nurse inserted an IV needle to give him a sedative. "All I remember is talking and then being wheeled back to the room."

Colorectal cancer is the second leading cause of cancer death in the U.S., after lung cancer. It's one of the easiest cancers to pick up early, since it usually begins as a growth called a polyp and grows silently for many years before spreading into the body. Screening people between the ages of 50 and 75 for colorectal cancer is so effective at preventing deaths that the United States Preventive Services Task Force (USPSTF) gives it an "A" rating , higher than its ratings for breast or prostate cancer screening.

People who have a strong family history or medical condition that increases their risk of colorectal cancer usually need to start getting colonoscopies before age 50. One doctors' group, the American College of Gastroenterology , recommends African Americans start getting colonoscopies at 45, because they're at higher risk of being diagnosed with colorectal cancer after it's already spread (and is thus more difficult to treat), and dying of the disease.

A colonoscopy is considered the "gold standard" screening test for colorectal cancer, since it's the only test that allows the doctor to inspect the entire large bowel and also the only test that allows immediate removal of the polyp. But it can be expensive (running from $500 to $3000 if you're paying out of pocket) and has some small risks, such as perforating the colon (which occurs in fewer than 1 out of 1000 people) and bleeding, which is more of a risk if you're on a medicine that interferes with clotting. And even though it's good at picking up pre-cancerous changes, it's not perfect.

For most people, the most bothersome thing about a colonoscopy is the "prep," or powerful laxative they must use to clean out their colon in advance of the test. (For a good laugh, read Dave Barry's account of his bowel prep experience). Colonoscopies need to be done in a monitored environment, since they require that the person receive a sedative. If the first screening colonoscopy doesn't show anything abnormal, most "average risk" people can wait 10 years before repeating the test.

Many insurance plans cover screening colonoscopy in people 50 and older. But what if you lack insurance, have a plan that doesn't cover it, are at high risk for a complication, or simply can't stand the thought of the test? The USPSTF says it's also OK to screen "average risk" people with high sensitivity fecal immunochemical tests (or "FIT"), which look for globin, a component of blood cells that's concealed in the stool. This test is a lot less expensive (usually under $30 if you're paying out of pocket; many insurance plans will cover it), but it must be repeated every year to be most effective. To do the test correctly, you have to take home two small brushes and cards on which you'll smear your stool after two different bowel movements.

Many doctors give their patients an older type of home test called the guaiac test, which involves three cards; the USPSTF says this isn't as effective as the FIT method, and no longer recommends it. You should also be aware that simply having your stool smeared on a single card (which doctors sometimes do as part of an office rectal exam) is not an adequate way to screen for cancer.

The USPSTF also says it's acceptable to do a flexible sigmoidoscopy every five years, in combination with high sensitivity fecal occult blood testing every three years, as a screening test. The flexible sigmoidoscopy is similar to a colonoscopy, except that the tube the doctor uses is shorter, so that he or she can only see the lower part of the large intestine, and might miss a cancer that's higher up. It doesn't require sedation, involves an easier bowel prep, and is less expensive, usually less than $300 if you're paying the full cost. According to a recent editorial in the Journal of the American Medical Association , research suggests screening with colonoscopy isn't necessarily more effective at preventing colorectal cancer deaths than screening with flexible sigmoidoscopy.

Keep in mind that if your fecal occult blood test or flexible sigmoidoscopy show anything concerning for cancer, you'll need to undergo a full colonoscopy, so that the doctor can look more thoroughly and remove any suspicious tissue for more tests. Also, even if you've had a "clean" colonoscopy within the past 10 years, you may need to repeat the test if you notice blood or other changes in your stool -- so don't ignore such symptoms.

What about screening for colorectal cancer using the fecal DNA test, or virtual colonoscopy? The USPSTF says there isn't adequate proof yet that the benefits of such strategies outweigh the harms, and gives them an "incomplete" rating. (The American Cancer Society and Multi-Society Task Force on Colorectal Cancer say they're acceptable). Both are expensive. Virtual colonoscopy requires a bowel prep, and exposes patients to radiation.

In recent years, many doctors have been offering patients a slightly easier colonoscopy prep, involving either a smaller amount of liquid laxative than in the past, or laxative pills instead. Taking the prep correctly is important, since even a tiny bit of stool could hide an abnormality. It's important to drink plenty of water and/or clear fluids on the day before the test, to keep hydrated. (Avoid anything red or pink, though). Some people suggest putting yellow Crystal Light lemonade powder in the prep and refrigerating it to make it more tolerable. If you have kidney or heart problems, tell your doctor, since there are certain types of preps you may need to avoid.

Stanley Thornton, now in his 50's, underwent a second screening colonoscopy recently, and said the prep was "much cleaner and nicer."

Many of my patients want to get a colonoscopy, but can't afford the upfront costs. The U.S. Centers for Disease Control funds some limited programs to screen low-income people for colorectal cancer. New York City has a relatively generous colonoscopy screening program for people who lack insurance.

Stanley Thornton urges everyone 50 and older with access to a colonoscopy to get the test. "The 'big C' is something we don't like to talk about in the black community, but we need to take charge of our health and get it done," he said. "Anything short of that, we're shortchanging ourselves."

A similar version of this article originally appeared on the website of New America Media.

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