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Study: X-ray spots colon cancers

A long-awaited federal study of an X-ray alternative to the dreaded colonoscopy confirms its effectiveness at spotting most cancers, although it was far from perfect.

Medicare is already considering paying for this cheaper, less intrusive option that could persuade more people to get screened for colon cancer. And some experts believe the new method may boost the 50 percent screening rate for a cancer that is the country's second biggest killer among cancers.

“We're talking about for the first time really screening the population,” said Dr. Carl Jaffe, an imaging expert at the National Cancer Institute who was not involved in the research.

In the new study, the largest of its kind, the so-called “virtual colonoscopy” identified nine out of 10 people who had cancers and large growths seen by regular colonoscopies.

But there were flaws, too. Among them: Radiologists sometimes misread the X-rays, leading them to spot polyps that weren't really there. That led to unnecessary follow-up testing.

The X-ray test's real value may be in showing who really needs a regular colonoscopy. It was better at ruling out cancer than at detecting it, suggests the report in today's New England Journal of Medicine.

The gold standard is colonoscopy, 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.

It requires general anesthesia and a missed day of work, not to mention preparation that uses pills or liquids to clean out the bowels.

The study focused on CT colonography, also known as virtual colonoscopy. It's a super X-ray of the colon that is quicker, cheaper and easier on the patient than traditional colonoscopies.

It, too, requires the bowel clean-out and has a potentially serious drawback – radiation.

Colonoscopies cost up to $3,000. The X-ray test costs $300 to $800; most insurers don't cover it so far, but Medicare is considering it.

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