 We
used to take the effectiveness of prostate-specific antigen (PSA) screening tests
for granted, but a major study published in The Journal of Urology in October
("The Prostate Specific Antigen Era in the United States is over for Prostate
Cancer: What happened in the last 20 years"), is calling our faith in the procedure
into question. So it's curtains for PSA, right? Not
so fast says Dr Laurence Klotz, a professor of surgery at the University of Toronto
and head of the Prostate Cancer Group at Sunnybrook and Women's College Health
Sciences Centre. "The alarm has been caused by media reporting, as well as the
title of the article, which was very provocative," he says. NO
SILVER BULLET
While he readily admits that PSA screening has its limitations,
Dr Klotz believes that it's still valuable. "I favour men being informed about
the pros and cons and having the option of having the test if they so choose,"
he says. "The evidence is strong that the PSA test improves the survival of men
with prostate cancer." He also fears the negative spin of this recent PSA research
is causing some unnecessary anxiety for those men who've already taken the test.
Dr Klotz points out that the PSA tests lead to cancer
being detected at an earlier stage — where treatment is more likely to succeed.
"We've seen a marked stage migration effect, due to PSA screening — no one
disputes this — and a fall in mortality, which many believe is in part related
to screening," he says. In recent years, North America's
prostate cancer mortality rate is down 25% — something Dr Klotz feels we
shouldn't lose sight of. He admits that this drop could have a number of underlying
causes and that no one knows for sure if it's related to PSA screening. "There
are reasons to think that it is, and other reasons to think not," he says. "We'll
know better in another five to 10 years," he adds, "when the screening studies
are more mature and the effects of screening the population outside of trial settings
is more apparent." BAD
OLD DAYS
And if you were considering ditching PSA tests altogether,
Dr Klotz has a dire warning. "We'd return to the old days when about one-third
of men newly diagnosed had metastatic disease and most of the remainder had locally
advanced disease that was incurable," he says. Dr Klotz laments the risks involved
in the procedure. "I would say that there are a lot of false-positives but there's
no other way to find PC without doing a biopsy." While
the uncertainty over PSA screening may be lingering in the air, Dr Klotz does
have good news about the future. He reminds us that there are promising new tests
in the pipeline that will likely replace PSA. "But in the meantime," he says,
"it's the best test we have." — By Marcello
Palmieri
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