NCPA - National Center for Policy Analysis

Virtual Colonoscopy

December 3, 2003

A new study finds that virtual colonoscopy, a method that uses a CT scanner for colon cancer screening, can be just as effective as traditional colonoscopy in finding polyps, the mushroom-like growths from which most bowel cancers arise.

The study of 1,233 people ages 50 to 79 who had both a virtual colonoscopy and a traditional one found that each method uncovered more than 90 percent of polyps at least 8 millimeters in diameter and about 88 percent of those at least 6 millimeters across. However, unlike a colonoscopy,

  • The 15-minute virtual screening test does not require sedation, and 70 percent of patients said it was more convenient.
  • CT scans may cost less than colonoscopies -- in the range of $500 to over $2,000 for a CT scan, compared to $2,000 for a colonoscopy.
  • However, most health insurers do not pay for the CT scan.
  • Sigmoidoscopy, which costs only a few hundred dollars and does not require sedation, examines only the lower half of the colon, where most cancers arise, and must be repeated every five years.
  • Barium enemas, which cost several hundred dollars and must be repeated every five years, are not as effective as colonoscopies and sigmoidoscopies in finding polyps.
  • And fecal occult blood test, which costs about $20; but should be repeated every year or two.

Experts say almost all small polyps are not cancerous and will shrink on their own; but when polyps are found during a colonoscopy, doctors will remove them regardless of size. Depending on the size of polyp considered large enough to warrant surgery, doctors would recommend surgery on between three percent and 30 percent of those in whom polyps are found using the CT scanner, and that requires use of a colonoscopy.

Source: Gina Kolata, "A Gentler Type of Colonoscopy Proves Effective," New York Times, December 2, 2003.


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