Colonoscopy, conflicts of interest, and cautionary tales

Dr. Michael Kirsch, who claims that “when I’m not writing, I’m performing colonoscopies, has published a blog post, “Is Colonoscopy the Best Colon Cancer Screening Test?

It’s an excellent piece, which I encourage you to read in its entirety.  It touches on medical conflicts of interest, comparative effectiveness research, the medical arms race, medical marketing and more.

But here’s how Kirsch ends the piece:

“To a gastroenterologist, 50 is a milestone year. This is the age that we pounce upon you to scour your colon to remove cancers-in-waiting. While we champion this test, and sincerely believe in its worth, it is not ideal. Here are some drawbacks.

  • The pre-colonoscopy cathartic cocktail
  • Anxiety
  • Discomfort (no it’s not always painless)
  • Cost
  • Risk of complications
  • High rate of negative results
  • Loss of a day’s wages or personal enjoyment
  • Need for a driver

What will gastroenterologists’ reaction be when a better test threatens to retire our colonoscopes? Will we defend colonoscopy against a simple analysis of a person’s stool which is just as effective? Will we claim that the research behind the new development is flawed? Gastroenterologists have successfully prevailed against CAT colonography, a competing test which examines the entire colon for polyps using a CAT scan. We have the edge in this duel since patients who pursue the CAT scan option must still take a vigorous laxative and, if polyps are discovered, they cannot be removed. Colonoscopy’s unrivaled advantage is that it can remove nearly all polyps discovered. It’s one stop shopping.  If radiologists perfect the technique of performing a CAT colonography without any required laxatives, then the scales may tip in their favor.

The above vignette is not a futuristic hypothetical creation. I suspect that colonoscopy and CAT colonography will be properly forced out during my own career as colon cancer screening techniques. Colonoscopy will still be performed, but only when some kinder and gentler screening test indicates that an individual has a high probability of harboring polyps. It will no longer be wielded in a buckshot fashion.  The number of colonoscopies being performed will be decimated.

When that happens, it will not be good news for the Kirsch family. But, it will be greater good news for everyone else’s family.”

Kirsch is worth following on a regular basis.  We linked to his piece, “Evidence-based Medicine in Disguise: Beware the Surrogate!” in our Toolkit’s Tips for Understanding Studies.

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Comments (2)

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Greg Pawelski

January 14, 2013 at 2:00 pm

A German study published in JCO and a Canadian study published in AIM came up with similar results: the chances of developing (and the risk of dying from) colon cancer within ten years of a negative colonoscopy were about one-fourth to one-third that of people who didn’t have the procedure. Then there is the chance a cancer starts in the “right” side of the colon (the part farthest from the rectum), colonoscopy does not lower the chance of dying. First question I asked my gastroenterologist during my Welcome to Medicare colonoscopy, was how good he was at spotting right-sided polyps. The procedure isn’t that good for cancers on the right side of the colon, so I have my false sense of security for ten years?