Colon Screening: 5 Things You Need to Know

The colonoscopy is the gold standard of colorectal cancer screening. Here's what you need to know.

Video: Learning About Cancer

Video: Learning About Cancer


4. How do I pick a doctor? Some recent studies have suggested that colonoscopies aren't as accurate as previously thought at detecting polyps. That's not a reason to avoid one; doctors still say it's the most effective screening test we have for a common cancer (except for the Pap smear, for cervical cancer). It is a reason to make sure you get the best possible care, and that, says Brooks, means tracking your doctor's stats with at least as much attention as you pay to A-Rod's during September.

You want to know how many colonoscopies she performs—experts say at least five a week is a good rule of thumb. She should also be tracking how often she finds a polyp, says Brooks. "In a general screening population, that should be between 15 and 25 percent of the time," he says. You want to know how often she completes a full exam of the colon, as opposed to stopping short of the cecum, or the beginning of the large intestine. (That may depend on whether the bowel prep has been done correctly and complicating digestive conditions, in addition to the doctor's skill.) Anything less than 90 percent of the time is worrisome, Brooks says. Finally, ask how long, on average, she spends withdrawing the scope from the colon. Anything less than about six minutes means the doctor is more likely to miss lesions, he says. Your doctor doesn't know the stats or pooh-poohs your attempts to get them? Find another one.

5. What are the alternatives? While the colonoscopy is held up as the gold standard of screening for colorectal cancer, you do have options if you want to be screened—but just not that way. Last year a handful of medical groups, including the American Cancer Society, updated their list of most recommended tests. The preferred alternatives: flexible sigmoidoscopy (in which a flexible tube is inserted in the rectum but not as far into the bowel as with a colonoscopy) every five years, double-contrast barium enema every five years, or virtual colonoscopy every five years. (There are other tests that look for signs of cancer in the stool, but the other three are preferred because they can find both cancer and precancerous polyps.)

Virtual colonoscopy, which is actually a CT scan, has gotten a lot of attention. But despite its addition last year to the list of recommended tests, the Centers for Medicare and Medicaid Services last month issued a memo saying it has tentatively opted not to cover the test. (And it is expensive—upwards of $1,000.) That preliminary decision is "surprising and disappointing," David Kim, a University of Wisconsin-Madison radiologist who performs the scans and has researched their effectiveness, writes in an E-mail. He's hoping that additional data will change the minds of the folks at CMS. Kim believes that if the final decision is no Medicare coverage, it "will markedly slow or even stop the implementation of CT colonography on a national scale." That, he fears, will mean unnecessary cancer deaths.