NEJM colonoscopy study's findings questioned by U.S. physicians : Shots - Health News Colon cancer specialists worry that results of a study published this week in the New England Journal of Medicine could be misconstrued, and keep patients from getting lifesaving cancer screening.

Colonoscopies save lives. Doctors push back against European study that casts doubt

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The findings of a big European study published this week in the New England Journal of Medicine seemed to cast doubt on just how beneficial a colonoscopy can be in preventing colorectal cancer, a leading cause of cancer deaths in the U.S. The results have generated a lot of controversy, and as NPR's Allison Aubrey reports, doctors are worried the findings have been misunderstood.

ALLISON AUBREY, BYLINE: Beginning back in 2009, thousands of healthy people in Norway, Sweden, the Netherlands and Poland between the ages of 55 and 64 were invited to get a colonoscopy. None of them had ever had one because, as Dr. Michael Bretthauer of the University of Oslo explains, colonoscopies are really not the norm there. The procedure enables doctors to look inside a patient's entire colon and to remove any polyps or abnormal tissue that could turn into cancer.

MICHAEL BRETTHAUER: Over here in Europe, you know, few countries offer colonoscopy screening. Most do not. So the big question we want to answer is, what is the benefit of colonoscopy screening to prevent colorectal cancer?

AUBREY: More than 10 years later, Bretthauer has published an answer to that question. And at first blush, it seems the benefits were not so impressive. His study found overall, the reduction in colon cancer deaths was so small, it wasn't even statistically significant. Now, this is surprising given studies done in the U.S. have linked colonoscopies to a nearly 70% reduction in deaths.

BRETTHAUER: Some people don't like the study because they believe it's a negative study.

AUBREY: When the study first attracted attention earlier this week, headlines did focus on the negative. One was "Screening Procedure Fails To Prevent Colon Cancer Deaths In Large Study." But it turns out this interpretation is misleading. So remember how I said thousands of people were invited to get a colonoscopy? Well, it turns out, most of them never showed up.

BRETTHAUER: Forty-two percent showed up. The rest did not show up - entirely correct.

AUBREY: So is it really much of a surprise that they didn't see much benefit given so many people in the study never got the procedure? That's akin to saying a vaccine doesn't work because people didn't get the shot. Here's Bret Petersen, a gastroenterologist at the Mayo Clinic.

BRET PETERSEN: The huge proportion of patients didn't follow through with their exam. So colonoscopy doesn't work well unless it's actually done. And results were tremendously skewed.

AUBREY: Now, this isn't the whole story. The researchers in Norway did do another analysis, including only the people who actually had the colonoscopy. Turns out they were less likely to get colon cancer and less likely to die. In fact, deaths decreased about 50%. Dr. Petersen says this is what he would expect.

PETERSEN: When one looks at those patients who actually did go forward with the exam, there was a statistically important reduction in cancer, much like the studies performed to date in North America.

AUBREY: Dr. Petersen is also president of the American Society for Gastrointestinal Endoscopy, which put out a statement affirming its position that colonoscopy is the gold standard in detecting and preventing colorectal cancer. Research scientists, including Douglas Corley, a gastroenterologist at Kaiser Permanente, have been evaluating the procedure for years.

DOUGLAS CORLEY: Colonoscopy as a single test done once is the gold standard for detecting colon polyps and colon cancer.

AUBREY: He points to national recommendations that adults be screened for colon cancer beginning at age 45 and says colonoscopy isn't the only option. Many people opt for stool tests they can do at home, which can detect blood or DNA changes.

CORLEY: If you are at higher risk for colon cancer, such as you've had close family members who've had colon cancer - especially if they're at a young age - then it's recommended that you have a colonoscopy.

AUBREY: Those who are not at high risk often opt for the stool-based tests. He says each screening approach has its pluses and minuses. And no matter which one you choose, the most important thing is that you actually do the screening.

Allison Aubrey, NPR News.

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