Study finds flaw in colonoscopy screenings
A new study from the American College of Physicians now published in the Annals of Internal Medicine indicates colonoscopy may play no role in preventing deaths from cancer that develops on the right side of the colon.
"What we found was the effectiveness of colonoscopy was completely different on the left side and the right side. It was highly effective for preventing left-sided colon cancer deaths, but didn't appear to be effective at all for preventing right-sided colon cancer deaths, which was a very surprising finding," said Dr. Nancy Baxter, Lead Author, Annals of Internal Medicine.
Previously, experts believed colonoscopy to be 90 percent effective at preventing colon cancer deaths. But researchers said the findings are so significant that number should be lowered to about 60 or 70 percent.
At age 60, Douglas Johnson's screening showed a benign polyp and now he has to have a follow-up within the next five years.
It is a little disturbing if you think you're okay and the right side could be the culprit, so they should develop a test that gets all sides," said Johnson.
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Johnson's doctor, and researchers behind the study, said the findings should help patients understand the limitations of the test.
"There is no perfect test. All tests have a certain sensitivity and specificity meaning that they have a correct false positive rate and a correct false negative rate, so no test is perfect," said Dr. Andrew Gotlin, Ryan Chelsea-Clinton Community Health Center.
Doctors said colon cancer may be more difficult to detect on the right side because it may be harder to reach with a scope. It may also be more difficult to prep the right side for the procedure. And the anatomy of flatter lesions on the right side may also make them tougher to find.
Medical professionals emphasize a test that contributes to a 60 to 70 percent reduction in cancer is still significant.
"What patients need to know is that this study does not show that colonoscopy is a poor screening test of colon cancer. In fact, colonoscopy is still probably our best test for screening for colon cancer," said Gotlin.
It's recommended men and women over age 50 who are at average risk should be screened with colonoscopy at least every 10 years.
Patients whose results have shown no abnormalities should also be sure to report any unusual bowel symptoms to their doctor.