Colonoscopy Best at Finding Cancer on Left Side of Colon

Posted on December 31, 2008

The Washington Post reports that the colonoscopy is much better at detecting colorectal cancer on the left side of the colon than the right.

The procedure does a good job of detecting early signs of disease on the left side of the colon, or large intestine, but is not as effective at spotting potential problems of the right side of the organ. This means a colonoscopy's success at preventing colorectal cancer deaths seems to lie with its ability to uncover so-called "left-sided" problems.

"We did find that colonoscopies are effective -- that's the good news. It's still one of the best screening tests for any cancer that we have," said study author Dr. Nancy Baxter, a colorectal surgeon with St. Michael's Hospital in Toronto.

"But it's not perfect," she added. "And it does not appear to be as effective in picking up growths on the right side of the colon as it is in detecting them on the left side."

The findings are published online Dec. 16 in the Annals of Internal Medicine.

That's disturbing because colon cancer can often be a killer if it isn't diagnosed early. A doctor gave one reason for the discrepancy, explaining that polyps tend to grow flatter on the right side of the colon. Doctors say it is still a great test that saves lives but patients really need a colon cancer test that is both more thorough and less invasive. The ultimate solution might be miniature robots that examine your colon but that's still a solution for the future and not available today.

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