Health

'Virtual' Better Than Actual? Unintrusive Colonoscopies

By CBSNews.com staff CBSNews.com staff

January 31, 2002 / 8:42 AM EST / CBS

Despite numerous public awareness campaigns, only two out of five Americans who should get screened for colon cancer actually do, which is troubling, considering colon cancer kills 60,000 people a year even though it is preventable with proper screening.

A newly released study in the journal Radiology concludes virtual colonoscopy is as effective as traditional colonoscopy at detecting clinically significant polyps.

While both traditional and virtual colonoscopies require patients to empty their digestive tract through suppositories or other medicines before the test, virtual colonoscopy, taken with a low-radiation CAT scan, is nearly painless, carries no risk of tearing the colon, and requires no anesthesia. And it takes about 1 minute versus 15-45 minutes for traditional colonoscopy.

In a study of 300 San Francisco veterans, the largest study to date, virtual colonoscopy detected 90% of large 1-centimeter polyps, up to 80% of medium-size polyps, and about half of the smallest growths detected by traditional colonoscopy.

Dr. Michale Macari, who has performed about 500 virtual colonoscopies at NYU Medical Center, has seen similar results. He says because small polyps--the ones detected only about half the time by virtual colonoscopy--grow so slowly, they are of little clinical significance. If patients come back for a regular 5-year screening, Macari says, they can then be detected.

"It's estimated that it may take one of these small polyps about 10 years to grow to be about 10 millimeters in size," he says. (Ten millimeters equals 1 centimeter.)

But several doctors who perform traditional colonoscopies expressed reservation. One told CBS 2's Paul Moniz a 50 to 90% detection rate is not enough for him and he wants the technology to improve before recommending it widely.

Doctors say if you have bleeding, anemia, and changes in bowel movement consistency, you should probably have a traditional colonoscopy because in those cases, doctors may need to do a biopsy and they cannot perform one with the virtual test.

Virtual runs $650 to $1,000 and is not covered by most insurances.