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Test
Predicts Prostate Cancer Death
The PSA blood test widely used to detect
prostate cancer can also predict who is most likely to die from
the disease, researchers said.
The study, in this week's New England
Journal of Medicine, added to evidence that the rate of increase
in prostate-specific antigen level may be more important for predicting
cancer than the actual PSA number.
The researchers said their study
of 1,095 men showed that men need annual PSA tests so that their
year-to-year change -- called PSA velocity -- can be monitored.
They found that when PSA levels
rose by at least 2 points during the year before surgery, about
one in four patients was dead from prostate cancer within seven
years. It raised the risk of death 10-fold.
But if the PSA level had been increasing
slowly before surgery, there was very little chance the patient
would die from a prostate tumor.
"This study provides, for the first
time, solid evidence that PSA testing over a period of time is
a reliable indicator of possible risk of death from prostate cancer,"
said Dr. Anthony D'Amico of Massachusetts General Hospital in
Boston, who helped lead the study.
Prostate specific antigen is a
protein produced by cells in the prostate, the walnut-sized organ
that sits against a man's rectum and produces the semen that carries
sperm. The higher the PSA, the more likely the prostate is irritated
by an infection or, perhaps, by cancer.
Prostate
cancer affects 220,000 U.S. men a year and kills about 29,000,
according to the American Cancer Society.
PSA HIGH
If a man's PSA looks high or looks
like it has risen recently, a urologist will usually recommend
a biopsy to remove some tissue from the organ to see if it is
cancerous.
"A man whose PSA is 3.5 may have
nothing to worry about if it was 3.49 the year before, but a lot
to worry about if PSA last year was 1," D'Amico said in a telephone
interview.
Starting around age 35 or 40, men
need annual screening to set their "baseline" PSA level, against
which change can be measured, he said.
"The nice thing about starting
at age 40 is most men at 40 have a PSA that is like 0.6 or something
like that," added Dr. William Catalona of Northwestern University
in Chicago, who also helped direct the study.
"If your next annual PSA goes to
1.4, well, you shouldn't wait until next year to check it again."
This contradicts the usual guidelines,
which suggest that men can relax until their PSA level reaches
4, Catalona said.
He got the idea of checking "PSA
velocity" while doing a large study of 36,000 men over 12 years.
"I had some men come in and their
PSA would be 0.6 one year, then 1.4 the next, then 2.4, then 3.2.
There would be an obvious trend, and I would say 'We can't do
a biopsy until the PSA reaches 4'," Catalona added.
"Then they'd come in and have a
PSA of 6," he said. The men would get immediate surgery to get
their prostates out and many times the cancer had already spread.
"Then they'd be really angry,"
Catalona said.
Prostate cancer can be a slow-growing
disease and some men are advised just to watch it carefully --
especially if they are older and likely to die of something else
before the prostate cancer becomes serious.
Reference
Source 89
July
8, 2004
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