If you're 50 or older, your doctor has probably started to nag: Get screened for colorectal cancer, second only to lung cancer as a cause of cancer deaths in the U.S.
Trouble is, the most thorough way to check for cancers and the polyp growths that can turn into them--a colonoscopy--involves an extremely uncomfortable bowel cleansing one day, followed by sedation and a look through your colon with a five-foot-long probe the next. Not surprisingly, many people pass. Only about a third of those over 50 have had any type of colorectal cancer screening. That's a shame, since 90% of such cancers can be prevented--and half of those who wait until they have symptoms will die.
Fortunately, a test that may be almost as effective but far less invasive is becoming an option. Many doctors are offering a "virtual colonoscopy," a new and still experimental screening test that could one day make the hated colonoscopy unnecessary for most people. Also called CT colonography, the procedure involves moving the patient through a computed tomography (CT or CAT) scan machine to produce hundreds of visual slices of the abdomen. Software can then transform those slices into a virtual trip through the colon, leaving the doctor with a computerized version of what he might see through a colonoscope, the lighted fiber optic tube used in conventional colonoscopies.
So far, studies suggest that a virtual colonoscopy can approach the efficacy of the conventional test in finding cancers (virtually 100%) and large polyps (about 94%). But Dr. Joel Fletcher, a diagnostic radiologist at the Mayo Clinic in Rochester, Minn., says more studies are needed before virtual colonoscopy can become routine.
Michael Brady, a 62-year-old health-care consultant from Chicago, can attest to the ease of the virtual colonoscopy relative to the actual one. The laxative he used to prepare for the virtual test was far milder, not requiring a rush to the bathroom every few minutes as the one for his conventional test did. He also didn't need sedation, and the CT procedure took about 30 minutes, vs. three hours for the regular test. A patient might miss a couple hours of work rather than a day or two for the conventional test.
In Brady's case, the virtual colonoscopy yielded a dramatic extra benefit. Because his entire abdomen was scanned, doctors at the University of Chicago Hospitals were able to see his abdominal organs as well. They spotted a lime-sized tumor on his left kidney, which was later removed. "The virtual colonoscopy certainly could have saved my life," Brady says.
THEN AND THERE. But Brady also got first-hand experience with virtual colonoscopy's big drawback: About 10% of those who take it will need to follow up with the conventional procedure to deal with polyps discovered. With the old test, polyps can be removed immediately with tiny tools operated through the colonoscope. Since Brady had intestinal polyps, he had to return.
Another disadvantage: Since virtual colonoscopies aren't an accepted screening test, your insurance isn't likely to pick up the $650 to $1,000 tab. A regular colonoscopy can run up to $2,000, but it's more likely to be covered.
Also, because the virtual test is new, patients should seek an experienced medical center, says Dr. Abraham Dachman, director of the CT department at the University of Chicago, which is one such facility.
More established options to colonoscopy: Stool samples can be checked for blood, barium enemas allow X-rays of the large intestine, and a sort of mini-colonoscopy, called a sigmoidoscopy, examines the lower colon. But a consensus is growing that these are far less effective in detecting cancers and polyps than a colonoscopy. So a virtual test may turn out to be the next best thing.
By Carol Marie Cropper
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