Effectiveness of colonoscopy screening

It has long been rumored that colonoscopy screening tests are 90 percent effective at locating cancer in your colon. Yet a new study published online in the Annals of Internal Medicine indicates that the screening method is not as effective as doctors thought, often missing cancers located on a person’s right side.

"New York Times" science reporter Gina Kolata explains the study and how it might affect your next doctor’s visit. To find out more, read Gina Kolata’s article, "Colonoscopies Miss Many Cancers, Study Finds," at the "New York Times."

According to Kolata, "I think there’s a problem with the biology of colon cancer, which is not as well understood as people had though; there’s a problem with the doctors performing the test; and there’s a problem with patients preparing for the test … so there’s three things that may be going on to explain why this test, although it is extraordinarily effective compared to almost any other test, is not quite what many people thought it was."

Kolata suggests a few things people can do to make sure their screening is effective: "One of them is you should really ask a lot of questions of your doctor … this is a test that many people find extremely unpleasant because you have to take these power laxatives that totally clean out your bowel. So one thing you want to do is make sure that if you’re going to go through all of this, first of all, you do it right — you’re very, very careful to take all that harmful laxative.

"Secondly … you take half the laxative the night before and half in the morning. Because … if you wait too long between taking the laxative and having the test, this really thick … mucus can pour into your right colon from your appendix and cover up polyps and make it hard to see them.

"A third things is check out your doctor. You should ask … how many colonoscopies does this doctor do — they should be doing at least three or four a day. What’s they’re detect rate? How often are they finding polyps? They should be finding them in about 15 percent of men and 25 percent of women. You should also ask them, how they know that they saw your entire colon — they’re supposed to get all the way through to your appendix."

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