Colonoscopies get the glory, but reasons for dramatic decline in colon cancer are unclear

Kevin Lomangino is managing editor of HealthNewsReview.org. He tweets as @KLomangino.

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Colon cancer is on the decline, and you’d be forgiven for thinking that colon cancer screening — and the increased adoption of colonoscopies in particular — is the reason.

Promotion of colonoscopies, a market worth more than $10 billion annually in the United States, is everywhere:

• In March, the Mayo Clinic’s social media director underwent a colonoscopy viewable live on the mobile app Periscope — an event covered unquestioningly by health news site STAT.

• Journalists like Katie Couric and Harry Smith have crusaded for colonoscopies in front huge national TV audiences — abdicating their professional responsibility to objectively vet claims of evidence.

• Advocacy groups are pushing vigorously to reach an 80% screening goal by 2018, even though screening is a preference-sensitive decision that an informed patient might reasonably decline.

• Public health agencies have splashed one-sided, pro-colonoscopy messages across billboards — and received one-sided, pro-colonoscopy coverage of their campaigns from some journalists.

But are colonoscopies really the driving force behind the colon cancer success story?

An editorial in the New England Journal of Medicine raising that question got no attention from health care journalists last week (at least none that we could find). We were alerted to the piece, written by Drs. Gil Welch and Douglas J. Robertson of Dartmouth University, by the comments from two smart physicians on Twitter, both of whom called attention to the editorial’s insightful closing paragraph:

Drs Welch & Robertson call for humility about the benefits of Ca screening. Last paragraph sizzles w wisdom https://t.co/c2oCzVipWg

— John Mandrola, MD (@drjohnm) April 27, 2016

Brilliant ending. Calling health journalists and PR staff… CC @HealthNewsRevu @garyschwitzer @ivanoransky https://t.co/olSl2ZIghz — Steven Tucker, MD (@drsteventucker) April 27, 2016

The paragraph they pointed to includes this nugget:

…overstating the benefits of colorectal-cancer screening may divert attention from colonoscopy’s downstream effects and potential harms. The majority of people undergoing screening are neither identified as having cancer nor protected from its developing, but they often endure repeated colonoscopy for surveillance of small polyps. Certainly, aggressive efforts to screen and perform follow-up colonoscopy in persons who are most likely too old or infirm to benefit has real potential to cause harm.

Why shouldn’t screening get all the credit for reducing the burden of colorectal cancer?

For one thing, the decline began showing up well before the benefits of increased screening would be expected to take effect, Welch and Robertson say. And the decline has been bigger than the effect found in any colon cancer screening trial — suggesting that screening can’t be entirely responsible. They also name a number of other plausible explanations such as better diets and more effective cancer treatments. You should read the entire piece to get the full flavor of their argument.

There’s nothing wrong with organizations wanting to advocate for more colon cancer screening awareness. But truly informing the public is different than mindlessly promoting a procedure. Journalists who cover these campaigns should always strive to provide context and avoid cheerleading. They should discuss costs, harms, and alternatives, and acknowledge that the evidence supporting colon cancer screening isn’t as bullet-proof as it’s sometimes portrayed.

We’ve made a point of calling attention to respected voices who question the evidence on colonoscopies when seemingly few others were doing so:

• We’ve linked to posts by Dr. Michael Hirsch, who does colonoscopies, and who nevertheless wonders, “Is colonoscopy the best cancer screening test?”
• We’ve quoted Dr. James Allison, an emeritus professor at the University of California-San Francisco in the Division of Gastroenterology, who says that lower-cost screening options such as stool tests may be overlooked in colonoscopy-centric media messages.
• We’ve highlighted concerns about the “80% by 2018” colorectal cancer screening campaign raised by Dr. Richard Hoffman. He said, “Rather than just promoting a message of more screening, media messages could help people think about screening smarter—a goal for health care to identify high-risk patients (those with a family history) who would have most to gain from screening.”
• We’ve examined why the Canadian healthcare system won’t pay for colonoscopies as a first-line screening test, particularly the fact that colonoscopies haven’t been proven effective at saving lives in randomized controlled trials.

The editorial by Welch and Douglas was another missed opportunity for journalists to highlight some of this context.