Problems with screening for prostate cancer

On first view, it seems so logical to screen for cancer. Unfortunately, this is an example of the frequent disconnect between theory and reality and as a result harm can be done to patients under the guise of protecting them.

The article below explores the reality of screening for prostate cancer. If you find this article of interest, I highly recommend that you obtain a copy of H. Gilbert Welch's book, Should I Be Tested for Cancer? Welch covers a wide range of screening tests and does a very clear job of explaining the pitfalls.




Preventing the Risks of Prostate Cancer Screening
http://tinyurl.com/c6n3oh



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.