* Test saves fewer than 1 man per 1,000 from dying
* Hundreds harmed by treating non-threatening tumors
* Critics say less screening will “cost men their lives”
By Sharon Begley
NEW YORK, May 21 (Reuters) – A task force advising the U.S.
government on Monday recommended against routine use of the
prostate-cancer screening test called PSA, or prostate specific
antigen, for lack of a discernible health benefit.
Like a draft proposal last October, the U.S. Preventive
Services Task Force gave PSA screening a D, for “don’t
recommend” in healthy men.
The reaction was fast and furious. Screening advocates
warned that the recommendation will cost lives, but critics of
PSA testing said thousands of men will be spared impotence and
incontinence as a result of needless cancer treatment.
A D means there is “moderate or high certainty” that a
procedure has no net benefit or that harms outweigh benefits. It
is a downgrade from the panel’s last PSA recommendation, in
2008, which said the evidence was insufficient to assess the
procedure’s risks and benefits, although PSA screening for men
75 and older was not recommended.
Now, however, “there is convincing evidence that the number
of men who avoid dying of prostate cancer because of screening
after 10 to 14 years is, at best, very small,” the task force
said in the May 22 issue of the Annals of Internal Medicine.
Doctors, therefore, should discourage it.
The recommendation does not preclude men from asking for PSA
screening, or doctors from offering it. But it could affect
whether insurers, including the government’s Medicare program,
cover the test’s $60 to $80 cost.
The only other screening method is the old-fashioned digital
rectal exam, which cannot detect small, early cancers. Neither
the exam nor PSA can distinguish slow-growing from aggressive
cancers.
About one in six American men will be diagnosed with
prostate cancer during his life; 2.8 percent, or a projected
28,000 this year, will die of it. Many cases pose no risk even
without treatment. Research has shown that between one-quarter
and one-third of 60-something men have prostate cancer, often
without knowing it. Three-quarters of men older than 85 years
have prostate cancer but few die of it.
PSA, a blood test, is a poor screening tool because PSA
levels can rise for reasons unrelated to cancer, including age
and prostate enlargement. Yet an elevated PSA level can trigger
a biopsy to check for cancer.
Most biopsies show no cancer, which means the PSA was a
false positive. But prostate biopsies that detect cancer do so
based on research from the 1840s, explained Dr. Otis Brawley,
chief medical officer of the American Cancer Society.
“As many as 70 percent of these lesions are cancer only by
this antiquated definition and not in behavior,” he said. That
is, they are indolent or inert and will not threaten a man’s
health or life.
Radiation oncologist Anthony D’Amico of Dana-Farber Cancer
Institute in Boston acknowledges that PSA screening causes
overdiagnosis, “but if you get rid of the PSA test, men will
suffer and die of prostate cancer,” he said.
“I’m shocked that they would let people die in order to
avoid incontinence and erectile dysfunction, which can be
corrected.”
CONFLICTING STUDIES
The task force analyzed 64 studies, but focused on two, both
published in 2009 and updated this year.
The U.S. study compared 76,685 men aged 55 to 74. About half
were assigned to receive annual PSA screening and half to “usual
care,” which sometimes included a PSA test. The study found no
evidence that PSA screening saved lives after 13 years.
The European study was similar, with about half of 162,243
men aged 55 to 69 getting regular PSA tests and half not. But
for every 1,055 men who were screened every one to four years,
there was one fewer death from prostate cancer after 11 years
compared to men in the unscreened group. That is the basis for
the task force’s conclusion that PSA screening for a decade will
prevent at most one man in 1,000 from dying of prostate cancer.
The trials themselves were imperfect, polarizing the debate
even further.
The American trial was marred by the fact that some men in
the “unscreened, usual care” group did receive PSA tests. Such
so-called crossovers can weaken a trial’s conclusions.
“With the rate of screening in the ‘unscreened arm’ matching
that in the ‘screened’ arm, you can never measure a difference”
in the death rates “even if one exists,” said D’Amico.
The trial scientists disagreed, saying the crossovers were
statistically equivalent to having fewer people in the trial,
said biostatistician Paul Pinsky of the National Cancer
Institute, a member of the study team. “But there was twice as
much screening in the intervention arm, and we did not find a
mortality benefit.”
The European study is actually seven studies, each from one
country. In five, the results mimicked the American findings: no
statistically significant reduction in deaths from prostate
cancer among screened men. But studies from Sweden and the
Netherlands showed benefits.
The European scientists and their supporters argued that the
Swedish trial in particular was strong enough to stand on its
own as evidence that PSA screening saves lives.
Perhaps the greatest problem with the European study is that
the screened men diagnosed with prostate cancer generally
received top-of-the-line care from academic physicians. If the
unscreened men developed prostate cancer, they received less
specialized, less aggressive care. “That means this was a trial
not only of PSA screening but also of aggressive vs.
non-aggressive treatment,” said Brawley.
WEIGHING HARMS
Against the tiny benefit of PSA testing, the task force
weighed its harms. At least 15 percent of PSA tests will trigger
a biopsy, after which up to one-third of men experience pain,
fever, bleeding, infection, difficulty urinating, or other
problems requiring medical attention, studies show.
If a biopsy finds seemingly malignant cells, as happens to
120 in 1,000 screened men, about 90 percent of men opt for
surgery, radiation or hormone-deprivation therapy. Up to five
men in 1,000 opting for surgery will die within a month of the
operation; 10 to 70 more will have serious cardiovascular
complications such as a stroke or heart attack.
After radiotherapy and surgery, 200 to 300 of 1,000 men
suffer incontinence, impotence or both. Hormone-deprivation
therapy causes erectile dysfunction in about 400 of 1,000 men.
“When you stack up those harms, the tiny or zero benefits do
not outweigh the risk,” said task force co-chair Dr. Michael
LeFevre of the University of Missouri Medical School. Because
PSA tests cannot distinguish between aggressive and indolent
cancer, said ACS’s Brawley, “men are rendered impotent and put
in diapers, and for what?” he asked. “They never really had
cancer in the first place.”
The task force is not saying no man of any age under any
circumstances should undergo PSA screening. “A D recommendation
does not preclude discussions between clinicians and patients to
promote informed decision making that supports personal values
and preferences,” it said. The recommendation is against routine
screening.
“Our recommendation should not preclude a physician offering
a PSA test or a man requesting it,” said co-chair LeFevre. He
would be glad to provide the test for his patients, he said, if
the decision were based on a clear understanding of the possible
benefits and harms. ACS’s Brawley agrees that “a fully-informed
man who wants to be screened in his doctor’s office should be
screened.” Only if physicians are prepared to explain all this,
including that PSA screening misses just as many cancers as it
finds, said the task force, can men make an informed choice.
Experts on both sides do agree that mass free screenings
offered by hundreds of urology clinics and hospitals should end.
“There is minimal discussion of risks and benefits; a pamphlet
isn’t going to do it,” said D’Amico. “But a lot of fear gets
invoked.”
(Reporting By Sharon Begley; Editing by Michele Gershberg and
Cynthia Osterman)
