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Prostate Cancer Test Benefits Black Men, Study Shows
The Hybritech® free PSA blood test is useful in detecting prostate
cancer among black men, reports a study to be published in the March issue
of Urology. Researchers also say the free PSA (fPSA) test
can be used to help black men avoid unnecessary and costly biopsies of
the prostate.
"This study is significant because it validates that this FDA approved
test will perform as reliably in black males as it does in whites," said
study co-author Kevin M Slawin, M.D., assistant professor at the Scott
Department of Urology at Baylor College of Medicine.
Black men have the highest rate of prostate cancer in the world, noted
co-author Alan W. Partin, professor of urology at The Johns Hopkins University
School of Medicine, adding that the prostate cancer rate for black men
is one-third greater than it is for white males. "These data should
help us better detect this important disease," said Dr. Parting.
Researchers undertook the study because prostate cancer manifests somewhat
differently in black men than it does in white men. Black men tend
to get prostate cancer at a younger age and, when the cancer is diagnosed,
it is often more advanced and more aggressive. Black males are also
more likely to die from prostate cancer than are white men.
"It is generally accepted now that the free PSA test adds important
information when the test adds this important information when the total
PSA level is modestly elevated in men undergoing screening for prostate
cancer. Such screening is likely to provide the most benefit to high-risk
populations like black males," Dr. Slawin said.
This multi-center study is the largest to compare fPSA results between
the two races. The study, conducted in seven major U.S. medical facilities,
used the Hybritech® free PSA assay manufactured by Beckman Coulter,
Inc. The assay is the only free PSA test approved by the FDA as a
safe and effective in helping diagnose prostate cancer.
There are conflicting theories about why there are prostate cancer differences
between blacks and whites. Some researchers believe the reasons are
biological, while others believe the prevailing factors are socioeconomic.
The latter group points to the fact that blacks are historically medically
underserved and tend not to seek medical treatment as often or as soon
as whites.
The new study in Urology finds no significant biological differences
between black and whites with regard to the performance of the fPSA test.
Another study published in Urology last year (Write, et. al.) found
that when socioeconomic factors were controlled, race did not predict a
poor outcome in patients with prostate cancer.
"We don't know why blacks have a higher rate of cancer or why they tend
to have less favorable outcomes," Dr. Slawin said. "However, early
detection of cancer is currently our best weapon in fight against prostate
cancer. So it is crucial that we can rely on our most effective screening
tool -- like the free and total PSA test -- to work equally well on all
men regardless of their race. This study shows that the Hybritech®
free PSA test works the same in both races."
PSA exists in several forms in blood, with some forms bound to protein
and others unbound ("free"). As with cholesterol testing, scientists
have found it useful to measure these various forms for better risk predictions.
The Hybritech® free PSA test is used as a follow-up for men who
have moderately elevated levels of total PSA (4 to 10 ng/mL). This
group has a 25 percent risk of having prostate cancer in Caucasians, and
a risk of from 30 percent to 50 percent in black men, compared to a 4 percent
risk for the general population of men over 50. But most of the men
with these moderately elevated levels of total PSA (in the so-called "diagnostic
gray zone") are found not to have cancer when biopsied.
Prior to development of the Hybritech® fPSA test, these men were
routinely subjected to repeat biopsies, which can be painful and cost $1000
or more each. The Hybritech® free PSA test better identifies
these men so they do not have to undergo unnecessary repeat biopsies. The
new study in Urology shows these same testing benefits apply to
black men. The data for the study were taken from the largest clinical
trial to evaluate a free PSA assay. That previous clinical trial,
reported in 1998 in the Journal of the American Medical Association
(JAMA) formed the basis for FDA approval of the Hybritech® free PSA
assay.
Among the study participants was Lascelles Anderson, Ph.D., a professor
of education ate the University of Illinois, Chicago. "I believe that the
Hybritech® free PSA test is a breakthrough, because it does reduce
the fear men will normally have of going in for exams, knowing that the
number of biopsies will be substantially reduced," he said. "While they
say that prostate biopsies is good in that respect. I found that
PSA testing is very very useful in my case and has resulted in lowering
my fears and anxiety about the existence of prostate cancer," said Anderson,
65.
Investigators participating in the new study published in Urology were
from The Johns Hopkins University, in Baltimore; Washington University,
in St. Louis; Baylor College of Medicine, in Houston; University of Washington
Medical Center, in Seattle; Loyola Medical Center, near chicago; UCLA Medical
Center, in Los Angeles and Brigham & Women's Hospital in Boston.
The study was supported by a research grant from Beckman Coulter subsidiary.
Beckman Coulter, Inc. is a leading provider of instrument systems
and complementary products that simplify and automate processes in life
science and clinical laboratories. The company's products are used
throughout the world in all phases of the battle against disease, from
pioneering medical research and drug discovery to diagnostic testing that
aids in patient treatment. Annual sales for the company totaled $1.8
billion in 1999, with nearly half of this amount generated outside the
United States. |
