WEDNESDAY, June 2 (HealthDay News) -- Two new tests promise to
cut down on the number of biopsies now taken from men suspected of
having prostate cancer, researchers report.
The tests -- still in the early stages of development -- might
also offer better clues about which cancers require immediate
treatment and which can be left for so-called "watchful waiting,"
researchers reported Tuesday at the American Urological
Association's annual meeting, in San Francisco.
Both tests check for increased levels of genetic material -- one
for the DNA of which genes are made, the other for the RNA that
carries the messages from those genes. And both tests appear to add
certainty to the suspicion of prostate cancer provided by the most
widely used test for prostate cancer, the prostate-specific antigen
(PSA) blood screen.
PSA testing is often used to screen men for prostate cancer. A
high blood level reading of PSA is often followed by a biopsy --
tissue sample -- to detect cancer cells.
However, "only one of three [such patients] is likely to have a
positive biopsy," noted Dr. Rakesh Singal, an associate professor
of medicine at the University of Miami Miller School of Medicine,
who presented one report at the meeting. "We wanted to come up with
a test that tells us which patients are likely to have positive
biopsies," to help spare men unnecessary procedures and worry, he
The test Singal described looks at blood levels of specific DNA.
Prostate cancer can increase those levels, because malignant cells
grow abnormally fast and cause the death of other cells, Singal
The study included 252 men referred for prostate biopsies
because of abnormal PSA test readings. Singal's team found that
high levels of the target DNA were significantly associated with
the presence of a cancer.
"What we think will probably happen in the future is that those men who have high PSA levels will [also] have this test," Singal said. "If the DNA levels are high they will have biopsies; if low, they can be observed periodically."
But for that to happen, the results of this study have to be
confirmed, he said. "We hopefully will find funding for a study in
a larger set of patients," Singal said.
The other test, described by Dr. E. David Crawford, a professor
of urology at the University of Colorado, is targeted to elevated
levels of PCA3 "messenger RNA" in urine. Again, elevated levels of
this genetic material are associated with the presence of a
In the study, nearly 2,000 men with elevated PSA levels or
abnormal results on a digital rectal examination (which measures
prostate enlargement) also underwent PCA3 urine tests, followed by
The PCA3 readings were significantly higher in those men whose
biopsies turned out positive for cancer, the team found.
In addition, "PCA3 level reflects the aggressiveness of cancer,"
Crawford said, so that the test could be used to single out
prostate cancers requiring immediate surgery or radiation
Further studies are needed to determine whether PCA3 testing
could serve that purpose, he said. In the meantime, the immediate
effect of the new data is to help develop "a new paradigm" for
early detection of cancer, in which PCA3 testing would go along
with PSA testing and digital rectal examinations, Crawford
That combination could reduce the need for biopsies, which are
both expensive, cause discomfort and are associated with a risk of
infection, he said.
According to Crawford, about a million biopsies are done in the
United States each year because of suspected prostate cancer.
"Anything you can do to cut down the large number of biopsies has
innumerable advantages," he said.
To learn more about prostate cancer, visit the
U.S. National Cancer Institute.