The PSA prostate cancer screening test does more harm than
good, a new study suggests.
How much harm and how much good?
"For every man who avoids a prostate cancer death due to PSA screening,
about 50 men have to be treated unnecessarily -- and a third of these men will
have serious problems with treatment," study co-author H. Gilbert Welch, MD,
MPH, tells WebMD.
The blood test detects prostate-specific antigen (PSA) in the blood. Rising
PSA levels may, or may not, mean prostate cancer. So men with suspicious PSA
levels undergo prostate biopsies.
Although vast numbers of men undergo annual PSA blood tests, many
professional groups, including the American Cancer Society, do not recommend
routine PSA screening for prostate cancer. They instead recommend the test only
for men who still want it after carefully discussing the risks and benefits
with their doctor.
The PSA test became popular in 1986. What have we learned about the test's
risks and benefits?
To find out, Welch, professor or medicine at Dartmouth University, and
urologist Peter C. Albertsen, MD, of the University of Connecticut, analyzed
data on prostate cancer collected by the National Cancer Institute and
population data from the U.S. Census.
The result: From 1986 to 2005, PSA testing resulted in the diagnosis of
about 1.3 million prostate cancers that would never otherwise have been
detected. More than 1 million of these patients were treated with surgery or
Over that time, deaths from prostate cancer declined. Taking a conservative
approach, Welch and Albertsen assumed that PSA detection of early prostate
cancers -- and not improvements in treatment -- was responsible for the entire
drop in prostate cancer deaths.
In that case, PSA testing would have saved about 56,500 lives. But some
943,500 men would have been "overdiagnosed."
"The overdiagnosed patient is one not destined to experience symptoms or
death from the cancer," Welch says. "This means people who were never going to
get a dangerous cancer get treated and suffer the ill effects of needless
treatment. Overdiagnosed patients cannot benefit from treatment because there
is nothing to be fixed, but they can be harmed."
PSA Benefit Smaller Than Supposed
In an editorial accompanying the study, Otis Brawley, MD, chief medical
officer of the American Cancer Society, notes that
two recent clinical trials of PSA screening argue against routine use of
the test. A U.S. trial found no benefit; a European trial found some benefit
but a very high rate of overdiagnosis.
The main problem, Brawley says, is that many early prostate cancers never
will cause problems. Although PSA tests lead to prostate biopsies that find
early prostate cancers, there's still no way to know which of these cancers are
dangerous and which aren't.
Yet it's still common for men to be urged to get PSA tests by those who
extol the benefits without ever mentioning the risks. They often learn of those
risks long after they've undergone costly and adverse event-prone
"Many men who thought their lives were saved by being screened, diagnosed,
and treated for localized prostate cancer are perplexed to learn that so few
benefit," Brawley notes.
Watchful Waiting for Prostate Cancer
What if a man decides to get regular PSA tests, but does not undergo
treatment if a low-risk cancer is detected?
That's a strategy called watchful waiting. It's more common in Europe than
in the U.S. The basic strategy here is to defer surgery or radiation therapy
and to have one's doctor keep a close eye on lower-risk prostate cancers.
Can it work? Martin Sanda, MD, director of the prostate cancer center at
Beth Israel Deaconess Medical Center, and colleagues evaluated 342 men who
deferred treatment for at least one year after prostate cancer diagnosis.
Half the men remained untreated or nearly eight years; the other half
eventually opted for treatment an average four years after diagnosis. These men
were compared with men who chose immediate treatment after diagnosis.
"Among those who held off on treatment, 98% survived. With immediate
treatment, the rate of survival was 99%," Sanda tells WebMD. "That tells us the
guys who held off treatment, if there was any downside in terms of prostate
cancer survival, it was very small."
Sanda agrees that PSA screening "is a double-edged sword."
"Our study points to one possible way to have your cake and eat it too: If
you have PSA screening and treat aggressive cancers, you get survival benefit
-- but if you're more selective about when to treat, you lower your risk," he
says. "If men and their doctors don't jump to the conclusion that every
prostate cancer has to be treated, we can mitigate the problem."
Sanda acknowledges that watchful waiting has its own downside: anxiety,
uncertainty, and perhaps symptoms of enlarged prostate.
For these reasons, Welch says watchful waiting is not a way out of the
"These men have already taken a hit: They've been told they have a diagnosis
of prostate cancer," he says. "By the time you are told you have prostate
cancer, you are all nervous, you have already lost some sense of well-being.
The real issue is, do you want to play this game?"
The Welch/Albertson study, and the Brawley editorial, appear in the Aug. 31
online issue of JNCI: Journal of the National Cancer Institute. The
Sanda study appears in the Aug. 31 early online issue of the Journal of
By Daniel DeNoon
Reviewed by Louise Chang
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