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Preventing the Risks of Prostate Cancer Screening

Since the advent of PSA testing for prostate cancer in the 1980s, tens of millions of American men, including me, have had the test in the belief that “screening saves lives,” even though this proposition itself was not tested. Urologists committed to PSA, knowing it had not been proven to reduce mortality, assumed that with time the evidence would flow in and PSA would be vindicated. Still, doctors grew concerned over the manifest overdiagnosis of prostate cancer, as my Perspective essay in the current Hastings Center Report notes.

Soon after my essay went to press the high expectations for PSA suffered a setback with the results of two randomized trials, one conducted here and the other in Europe, published in the New England Journal of Medicine.   It appears that the test saves few lives if any, and leads to the treatment of perhaps 50 men for each life spared.

Before PSA, asymptomatic prostate cancer could not be detected, and when cancer finally became apparent patients did not have long to live. PSA enables the detection not only of asymptomatic cancer, but also indolent cancer. No sooner was PSA testing instituted than prostate cancer came to be diagnosed at a rate beyond anything in the history of medical statistics, according to the book Prostate Cancer Screening. In 2007 it was estimated that a million American men had already undergone treatment for prostate cancer that might never have endangered their health, and with 200,000 being diagnosed with the disease annually, the million will double soon enough.

Such an epidemic of diagnosed cancer, followed inexorably by harming treatments, is something no one could actually have intended when PSA testing went into effect. So disconcerting are the effects of the PSA revolution that some researchers now refer, with or without irony, to the “risk of diagnosis” of prostate cancer rather than the risk of the disease per se.

The more questionable mass screening for prostate cancer looks–and in the light of recent studies its benefits look dubious indeed–the better finasteride appears. The more troubling the manmade epidemic of prostate cancer, the more appealing a drug able to reduce the incidence of the disease and, as research shows, make PSA itself a more accurate instrument. As a number of the authors of the original paper on the Prostate Cancer Prevention Trial (PCPT) wrote in defense of finasteride in 2008: “The effect of screening on morbidity is uncertain, and the human and economic cost of prostate cancer treatment is substantial. These circumstances make preventing this common disease an attractive health strategy.”

Some of the more zealous advocates of PSA testing have become advocates of finasteride not least because it mitigates the woes arising from PSA testing. A slippery slope thus runs from PSA to finasteride–slippery because finasteride may carry significant risks. The PCPT found that the rate of high-grade or aggressive cancer was significantly higher among men who took finasteride than those who did not. If not for the straits we find ourselves in as a result of PSA testing, it is unlikely that a drug under a caution flag would even be considered for use by tens of millions of healthy men for years on end.

Given that PSA was approved by the FDA in 1986 not as a screening instrument but a means of monitoring the course of prostate cancer itself, it seems that from the start screening for prostate cancer has been a tale of unintended consequences. In 20 years we have gone from the use of PSA for mass screening without proof of its efficacy to the proposed general use of finasteride (approved by the FDA for treatment of benign prostatic hyperplasia, not prevention of prostate cancer) with its safety still in question. If “screening saves lives” is a catchy line, what of “a pill that prevents cancer”? Patients contemplating PSA testing need to know what they are getting into–and doctors looking to finasteride to relieve the dilemmas of PSA should think twice.

Stewart Justman is professor of liberal studies at the University of Montana and author of Do No Harm.

Published on: April 7, 2009
Published in: Health and Health Care

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