The following is a guest blog post by Alan Cassels, a pharmaceutical policy researcher at the University of Victoria and the author of Seeking Sickness: Medical Screening and the Misguided Hunt for Disease (Greystone, 2012). The opinions are his; you are welcome to your own.
While the Beatles might have famously sang that “All you need is love”, according to CBS News, you may also need other stuff, like medical screening tests. Critical…essential screening tests CBS called them.
We media consumers who are living our lives naïvely unaware of impending medical problems, will learn very little from this CBS two-part series on medical screening “The routine screening tests critical to women’s health” (Feb. 16) and “The routine screening tests essential to men’s health” (Feb 18) except that there are a battery of lifesaving tests that we allegedly need to do to keep healthy. In two short videos, and accompanying text, these articles are listicles, portraying many screening tests as necessary, vital, lifesaving and without any downsides. This is an uninformative message to leave with the viewers.
We should welcome good journalistic reporting of medical screening recommendations especially given the “better safe than sorry” culture in which we are all swimming. Let me, however, state my strong belief up front: In any story about medical screening, (which is looking for signs of disease in otherwise healthy people), if the story doesn’t mention the concept of “overdiagnosis” either directly or indirectly, then that story has a fatal flaw. Why? Because all screening tests involve some degree of overdiagnosis and this means people will be harmed.
Sadly this pair of CBS stories conspicuously never broaches the subject of overdiagnosis (a topic so vital that entire conferences are now dedicated to examine ways to prevent it – CBS should attend and report on one of these events), though they did briefly outline that for many people current screening recommendations are confusing. The story on women’s required screening tests tells us that “mammograms, pap smears and colonoscopies have the potential to save millions of lives. But many women still don’t know when they’re supposed to start getting them or how often the tests are really needed.”
Clearly there’s confusion, but boy, isn’t that a great subject for a story? Why is the public so confused about recommendations around screening? Clearly anyone watching how prostate and breast cancer screening recommendations have been trending over the last few years will know that the two most well-studied and evidence-based forms of screening on the planet have recommendations that are moving targets and they all seem to move in the same direction: more conservative. That is, what was recommended last year or even last month may not be recommended today. These shifting sands are the terrain that any good reporting on medical screening has to navigate because new evidence emerges constantly, often revealing vast disagreements over how effective or safe medical screening tests are.
Some groups used to call for more prostate cancer screening and more breast cancer screening more often and starting at earlier ages than what is generally recommended today. Why? Because better research is capturing the problem of overdiagnosis, alerting us to the many issues related to false positive and false negative findings, and reminding us that there is a always the potential for harm, both psychological and physical. Despite the marketing of breast cancer screening’s lifesaving potential, most people don’t know that the yield is very low. The best systematic evidence from the Cochrane Collaboration says that says you have to screen about 2,000 women for ten years to save one woman dying of breast cancer yet you will cause about 200 women to undergo psychological distress and ten will be treated unnecessarily.
What about talking about the sources of confusion around screening recommendations? Isn’t it of keen interest to the viewers that the most reliable committee on screening in the US, the United States Preventive Services Task Force produces guidelines on mammography recommending women start regular screening at age 50 and do it every two years till age 74 but the American Cancer Society says women should get a mammogram every year starting at 40 “and continuing as long as a woman is in good health.”
One group recommends screening twice as often as another group? Does this have anything to do with the independent, science-based orientation of one group (the USPSTF) versus the advocacy, fundraising and professionally-invested positioning of the other (the ACS)? CBS’s two-part report could have touched on the professional and financial conflicts of interest that are inherent in any medical enterprise and inform the viewer that there are valid reasons why not all recommendations are equally reliable.
For men, the fact that the many controversies over PSA testing are never broached in this story was a missed opportunity. The report notes that “PSA guidelines recommend against screening for prostate cancer, but some doctors recommend getting a baseline test at age 40.” What it didn’t say that is that if you consulted the most unbiased and authoritative source on PSA screening (the USPSTF), you would have found they give the big thumbs down to baseline bafflegab and simply say don’t routinely offer PSA tests for healthy men. The reasons are straightforward as the test has left hundreds of thousands of men impotent, incontinent or both due to the treatment, with very few lives saved. Others have awarded it the title as the “Poster Child for Overdiagnosis.” I described prostate screening in a previous blog post, saying that the PSA test is a “simple blood test that unleashes a cascade of interventions, worry and medical activity.”
Each of the screening tests mentioned, including those for breast, cervical and colon cancer, blood pressure, glucose and cholesterol also fail to discuss any downsides for which there are many. And don’t get me going why those guidelines are all over the map with some groups recommending never testing cholesterol, to others recommending it be checked almost in utero. The suggestion that otherwise healthy people need to be constantly, proactively probed and scanned for impending disease, without the discussion of the benefits and harms represents what Dr. David Sackett called the arrogance of preventive medicine, which often comes across as aggressively assertive, presumptive, and overbearing. I would politely ask any media outlet to take things to the next level on screening by challenging this arrogance instead of promoting it.
Bottom line for me: people do “need” something, perhaps in addition to love. They need high quality information about medical screening. They need to know there are perfectly good reasons why screening is controversial and recommendations clash. They need to know that harm can mount when screening recommendations are made for too wide and too unselective an audience.
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