PUMPING IRONY: My Gut Instincts

New studies on the efficacy of colonoscopies are less than persuasive.

Big news on the colonoscopy front always gets my attention, and a couple of headlines last week got me thinking again about my decision to avoid this particular rite of passage.

Colonoscopy Conundrum

On Thursday, researchers from the Huntsman Cancer Institute at the University of Utah released a report showing that a “clean” colonoscopy result does not always mean you’re going to be free of cancer in the next few years. And then on Friday, our local newspaper of record lauded a new alternative to colonoscopy that Mayo Clinic doctors suggest is as effective as the current screening — and much less, shall we say, invasive.

As I’ve noted in several columns over the years, I’m among the minority of geezers who harbor serious doubts about the efficacy of all disease-screening procedures, especially colonoscopies. This, despite the fact that both of my parents died of cancer that sprouted from their colons. Call me crazy, but in the dozen years since I first heard a friend or sibling or doctor plead with me to have my own colon checked out, evidence of the procedure’s shortcomings — and even dangers — continues to mount. And this week’s headlines only reinforce my view.

Once you hit 50, conventional medical wisdom demands that you have a colonoscopy every 10 years as a way to prevent a cancerous eruption in your gut. But, as the Huntsman study notes, in 6 percent of cases where patients came away from the procedure with a clean bill of health, colorectal cancer was diagnosed three to five years later. “Not only did we find that colonoscopy isn’t perfect, we discovered a number of factors associated with these ‘missed’ cancers,” lead study author N. Jewel Samadder, MD, MSc, told the journal Gastroenterology. “They tended to appear in patients over the age of 65, patients with a family history of colorectal cancer, and patients in whom polyps were previously found.”

So, even if I gave into the pleadings of my doctor and let some gut specialist explore my intestines with a camera and whatever it is they use to trim any perceived dangers there, it may have no effect on my relative propensity to someday be laid low by the big C.

The folks at Mayo have a better idea: Just send them some of your poop and they’ll tell you — within a certain margin of error, of course — whether you should be rushed into the hospital for surgery. Their clinical trial showed the test was 92 percent accurate, according the results published in the venerable New England Journal of Medicine.

The test kit, called Cologuard, is about to be trotted out before a U.S. Food and Drug Administration committee, where I assume the folks from Mayo will divulge that the clinical trial that showed the reliability of the test was financed by the company that invented Cologuard. I’m sure they will also point out that the test resulted in false positives in 10 percent of the cases studied. To this point, Thomas Imperiale, MD, lead author of the study, told the Star Tribune that false positives would simply send stressed-out patients to get a colonoscopy they would’ve gotten anyway if the new, more convenient, test was unavailable.

You can evaluate that line of reasoning for yourself, but I’m not finding it very persuasive. I tend to return to studies referenced by Nortin Hadler, MD in his book Rethinking Aging (University of North Carolina Press, 2011), which report a couple of sobering factoids: (1) Major complications occur in as many as two patients out of every 1,000 who submit to colonoscopies, and (2) out of 170,000 people in a randomized UK study, only 500 who submitted to colonoscopy were treated as a result of the screening. So, about .03 percent of patients may have been helped by the procedure, while as many as .02 percent of patients may have experienced major complications. Just doesn’t seem like decent odds to me.

Neither Hadler nor myself would suggest that you shouldn’t go and get a colonoscopy if you think you’re at high risk for the disease. Everyone gets to make their own decisions in these situations. For myself, last week’s headlines did nothing to change my mind.

, an Experience Life deputy editor, explores the joys and challenges of aging well.

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