There’s been a lot more noise lately about the overuse of medical testing – and over-treatment and over-medicalization in general. Frankly, we’re glad to see it. And we hope it will finally lead to some change (long overdue!).
The latest outcry has included an excellent opinion piece that ran a few weeks ago in the New York Times. In it, Drs. Lisa M. Schwartz and Steven Woloshin the Dartmouth Institute for Health Policy and Clinical Practice clearly and powerfully explain why, in the words of the title, “Endless Screenings Don’t Bring Everlasting Health.”
Certainly, the rationale behind screening seems obvious. The earlier cancers are diagnosed, the more often lives will be saved, right? With enough screening, we might even stop cancer.
If only. Finding cancer early isn’t enough. To reduce cancer deaths, treatment must work, yet it doesn’t always. Second, it must work better when started earlier. But for some cancers, later treatment works as well. (That’s why there is no big push for testicular cancer screening — it is usually curable at any stage.)
And some of the worst cancers aren’t detected by screening. They appear suddenly, between regular screenings, and are difficult to treat because they are so aggressive.
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For most of us, the chance of dying of cancer in a given 10-year period is small: less than 1 percent. So regular screening with a proven test may bring a 20 percent reduction in a 1 percent risk over a decade. Put another way, two deaths would be prevented for every 1,000 people screened during that period.
And what of the other 998 whose fate was not changed by screening? Some of them will have been harmed.
The most familiar harm is a false alarm: The screening test is abnormal, but in the end there is no cancer. False alarms matter because the follow-up tests needed to rule out cancer can be painful, dangerous and scary.
But overdiagnosis — the detection of cancers never destined to cause problems — is arguably the most important harm of screening. Some cancers grow so slowly that they would never cause symptoms or death. When screening finds these cancers, it turns people into patients unnecessarily.
Go read the whole thing. It’s that good at making sense of a sometimes hard-to-grasp issue.