Prostate cancer screening not backed by good evidence
A version of this commentary appeared in the Vancouver Province, Winnipeg Free Press and the Halifax Chronicle Herald
It’s Movember, and the kick off to prostate cancer charitable activities of all stripes begins in earnest, where we’ll be surrounded by recommendations from charities, doctors and media to get screened for the disease.
Last summer I was asked if I would debate a prominent urologist in Vancouver over the value of the PSA test, a simple blood test to determine a man’s risk of having prostate cancer. This was what I’d been waiting for. I had just published Seeking Sickness, a book about medical screening and was eager to see if anyone could step forward and publicly argue against what I was saying about PSA testing — which I think is a bad idea.
Not to mention that I have liked to debate since my days in Military College, where we debated wearing capes.
Having studied the research behind the PSA test, I concluded that the PSA test is a dud.
Yes, it is true that prostate cancer is a condition that kills about three per cent of the male population, so it would seem to make sense to employ a ‘screen early and screen often’ mentality.
The main problem with looking for cancer with a PSA test is that the test finds evidence of cancerous cells in the prostates of most men who are getting to be a certain age (I won’t say old).
Changes to our prostate cells are not rare at all, and come as naturally to older guys as wrinkles and grey hair. While we’d all like to avoid the rare and rapidly fatal form of prostate cancer, the PSA test mostly finds the slow-growing type that will never go on to hurt us. Yet usually if a ‘high’ PSA score is found, doctors and patients strong biases are to treat the cancerous cells.
Physician and author Dr. Gilbert Welch is an expert on cancer screening and calls PSA testing ‘the poster child for over-diagnosis.’ He estimates that nearly two million American men have been unnecessarily treated for prostate cancer — treatment that leaves as many as 40 per cent of them incontinent or impotent. As one doctor told me: “a PSA test won’t let you live longer, but your life will feel longer.”
Nevertheless, my research on PSA tests found that there are still many players in the game promoting the test, especially some of those individuals and organizations with arguably vested interests or much at stake: some urologists who do prostate surgery, radiation therapists who apply the radiation, drug companies who supply treatments and organizations who try to raise prostate cancer awareness.
The largest prostate cancer awareness group in the US gets financial support from some of these groups and is even supported by Depends, the company that makes adult diapers.
Yes, many raise money for these charities in good faith, because they appreciate what men diagnosed with prostate cancer endure and want to improve their quality of life. Fair enough. Just make sure your favoured charity is not encouraging a test that can often do more harm than help, and supplying men with balanced information before asking them to take the test.
But back to the debate. The Urologist and I were supposed to meet for a taped TV debate. Finally someone was willing to step into the ring with a little punk like me!
And then he bailed.
The reason given, I heard from the organizers, was that he didn’t want to see an upstart get publicity for his book and its message. He’s probably right: If people read independent analyses of PSA testing they’d come away with a different picture of the test than what many urologists and cancer charities put forward.
My skepticism around the PSA test was vindicated earlier this year when a respected group that provides ‘gold-standard’ independent analyses of screening, the United States Preventive Services Task Force (USPSTF), announced that healthy men should not be screened with a PSA test, pure and simple.
There’s plenty of money to be made from telling men that they have disease lurking in their bodies, and the PSA is a classic case of this. Offering a screening test to a perfectly healthy person demands that we supply a good answer to the question: What if the treatment is worse than doing nothing?
Was that the question that scared my opponent off? Maybe he backed out because someone told him I was going to wear a cape.
Alan Cassels is an expert advisor with EvidenceNetwork.ca and a drug policy researcher at the University of Victoria. He is the author of the new book, Seeking Sickness: Medical Screening and the Misguided Hunt for Disease [Greystone, 2012]. He is still willing to debate any urologist on the value of the PSA test.
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