Updated

Medicare won't pay for the so-called virtual colonoscopy procedure, concluding Tuesday that there's inadequate evidence to support the cheaper, less intrusive alternative to the dreaded colonoscopy.

Some experts had hoped that popularizing the X-ray procedure would boost screening for colon cancer, the country's second leading cancer killer. Screening to spot early cancer or precancerous growths has resulted in fewer deaths over the last two decades.

But in a decision posted on its Web site, the Centers for Medicare and Medicaid Services said that the test does not qualify for Medicare coverage. The memo noted that the procedure is performed on people without symptoms and cannot, in itself, rid a patient of precancerous growths, like a regular colonoscopy can.

Medicare does cover regular colonoscopies, in which a long, thin tube equipped with a small video camera is snaked through the large intestine to view the lining. Any growth can be removed during the procedure.

CT colonography, also known as virtual colonoscopy, is a super X-ray of the colon that is quicker, cheaper and easier on the patient, but involves radiation. Both procedures involve preparation to clean out the bowels.

The Medicare memo notes that the virtual colonoscopy has shown better precision in detecting larger polyps than smaller ones.

There's been some division of opinion in the medical community over the virtual colonoscopy. Some doctors question its utility since, if a polyp is found, a regular colonoscopy would typically have to follow, anyway.

Others support it, saying it can result in early cancer detection. The American Cancer Society recommends it as an alternative to a regular colonoscopy.

A concern for Medicare officials, according to their decision Tuesday, was the effectiveness of the procedure for the Medicare population — people 65 and older — as opposed to younger patients. More data is needed to answer that, Medicare said.

The U.S. Preventive Services Task Force opted last fall not to give its stamp of approval to the virtual colonoscopy, citing the risk of radiation among other factors. Medicare said it took that decision into account in reaching Tuesday's determination, which is final.

Some private insurers cover the virtual procedure but others don't. Colonoscopies cost up to $3,000 while the X-ray test costs $300 to $800.

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On the Net:

Centers for Medicare and Medicaid Services: http://www.cms.hhs.gov/