According to a
new study, two widely used tests for prostate cancer
failed to save lives, adding to the debate over whether men
should be screened for the disease. The study was
small--only 1,002 men--and will not be the
final word on the issue. But it may hint at what lies ahead
when the results of two large studies of prostate
cancer screening appear in a few years.
looked at two screening tests that are performed millions
of times a year in the United States: a blood test that
measures prostate specific antigen, or PSA, and a
digital rectal exam, the rubber-glove test in which a
doctor feels for abnormalities in the prostate through
the rectal wall.
John Concato, a clinical epidemiologist at the VA
Connecticut HealthCare System, said that for now doctors
should tell men that screening tests for prostate
cancer are not perfect, and men should decide for
themselves whether to get screened.
Doctors have long
known that some cases of prostate cancer can be so
slow-growing that they never cause symptoms, much less
death. In addition, surgery and radiation treatment
for prostate cancer can cause incontinence and
impotence. So for some men, detecting prostate cancer
early through screening can do more harm than good.
In addition, the
PSA tests can yield ambiguous results. Most men who
undergo a biopsy because they have elevated PSA levels do
not have prostate cancer. And some men with low PSA
levels do have cancer.
organizations differ on their screening recommendations. But
generally, most say men should first be informed
about the risks and benefits of screening.
"We should tell patients about the
uncertainty," said Howard Parnes of the National
Cancer Institute. "All too often we behave as
if we know screening is a good thing."
In the study,
published in Monday's Archives of Internal
Medicine, researchers compared two groups of men treated
at 10 Veterans Affairs medical centers. One group
consisted of 501 men who were diagnosed with prostate
cancer and later died of that disease or other causes.
Researchers chose 501 men who matched the first group for
age and other factors, but who remained alive.
found that the men who were alive were no more likely to
have been screened than the men who had died of prostate
cancer. The study was based on data from 1991 through
1999, the early years of PSA screening.
support an earlier review by the U.S. Preventive Services
Task Force. That agency said in 2002 that it found
"insufficient evidence" for a
recommendation that men be screened.
Cancer Society says men starting at age 50 should be
informed of the risks and benefits of screening and then
make their own decisions, but higher-risk men,
including African-Americans, should be screened
annually starting at age 45.
The prostate is a
gland the size of a walnut under the bladder that makes
fluid for semen. Prostate cancer is second only to skin
cancer in its prevalence among American men. More than
232,000 U.S. men are expected to be diagnosed with it
this year, and about 30,000 will die of it. A diet
high in fruits and vegetables may reduce the risk.
For now, cancer
experts must wait until 2009 for better answers. That is
when results are expected from large studies of the PSA test
in nearly 300,000 U.S. and European men.
And if the large
trials show little benefit from screening? "It would
certainly create a great deal of chaos," said Durado
Brooks, director for prostate cancer at the American
Cancer Society. (AP)