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Most common cancer for men
Prostate Cancer: More Aggressive Detection Needed,
New EPCA Marker May Help
May 16, 2005 - Prostate cancer is the most common
type of cancer found in American men and early detection is a key to
preventing death. One study released this weekend says a more aggressive
means of detection is needed after 25 percent of men studied were found
to be at high risk despite low PSA – high PSA is currently the marker
for high risk. The good news comes from a study of a new blood protein
associated with prostate cancer, called EPCA or early prostate cancer
antigen, that can successfully detect prostate cancer in its earliest
stages.
The American Cancer Society estimates that there
will be approximately 232,090 new cases of prostate cancer in the United
States in 2005, and 30,350 men will die of this disease.
In the clinical study of EPCA, researchers say the
marker also successfully avoids the problem of false positive results
that plagues prostate-specific antigen (PSA) testing.
Study results appear in the May 15, 2005, issue of
Cancer Research. The lead author is Robert H. Getzenberg, Ph.D.,
professor of urology and director of research at the James Buchanan
Brady Urological Institute at Johns Hopkins.
The traditional two-step approach of PSA testing
and digital rectal examination has helped doctors identify prostate
tumors early, while the cancers can still be cured. But PSA testing,
like many disease-screening procedures, misses some cases of cancer and
in other cases erroneously highlights noncancerous conditions.
"This new blood test, when coupled with PSA
screening, may help reduce the number of both unnecessary biopsies and
undetected prostate tumors," said Getzenberg, In addition to being
highly sensitive to prostate cancer, the EPCA test is also very specific
to it, meaning that other cancers and benign prostate conditions are not
detected, thus boosting doctors' confidence that a positive EPCA test is
really a sign of prostate cancer, added Getzenberg.
"Once this test is refined and approved for general
use, it will have an impact on the detection and treatment of prostate
cancer," said Getzenberg.
For the current study, Getzenberg and colleagues
developed a simple test that would detect EPCA in the blood and then
measured the EPCA levels in 46 patients, including those with prostate
cancer (12 patients), bladder cancer (six patients), colon cancer (two
patients), kidney cancer (one patient), spinal cord injury (seven
patients) and noncancerous prostate inflammation (two patients), and 16
healthy individuals. The study was conducted at the University of
Pittsburgh while Getzenberg was a member of its faculty.
The researchers found that EPCA levels were high in
11 of 12 prostate cancer patients (92 percent) and low in all of the
healthy individuals. Only two bladder cancer patients and none of the
other patients had elevated EPCA levels, suggesting that for this study,
the test was correct 94 percent of the time. For comparison, only
one-quarter of patients who undergo biopsies because they have elevated
PSA values are actually positive for prostate cancer, while as many as
15 percent of those with low PSA values were found to have prostate
cancer as detected by biopsy, according to Getzenberg.
Larger clinical trials are under way to further
refine the EPCA test, to make it more sensitive so it can pick up even
the smallest traces of the marker, and to verify its usefulness for
detecting prostate cancer in a larger sample of patients, said
Getzenberg.
Prostate cancer in 25% of high-risk men with
'normal' PSA levels
The study highlighting the need for more aggressive
screening for the disease was a Fox Chase Cancer Center study of 520 men
at high-risk of developing prostate cancer in which 25 percent were
diagnosed with the disease despite having a low PSA. The findings were
presented Sunday at the American Society of Clinical Oncology 41st
Annual Meeting.
"This study demonstrates that we can find cancer
earlier in high-risk men if we use more aggressive screening criteria,"
said Andre Konski, M.D., clinical director of the Prostate Cancer Risk
Assessment Program at Fox Chase and lead investigator of the study. "Men
at high risk of prostate cancer are more likely to develop the disease
at a younger age. Catching the cancer early before it has spread is
critical to curative treatment."
Today's report detailed the results of a study
involving the first 520 men enrolled in Fox Chase's Prostate Cancer Risk
Assessment Program between 1996 and 2004 (200 Caucasians, 315
African-Americans and five others). African-American men and men with a
family history of prostate cancer who are between the ages of 35 and 69
are eligible to enroll in the Prostate Cancer Risk Assessment Program.
Caucasian men testing positive for the BRAC1 gene are also eligible.
"Our study criteria dictated that men with an
abnormal digital rectal exam and a PSA level between 2 and 4 would
receive a biopsy," explained Konski. "While an abnormal digital rectal
exam could trigger a physician's concern about the possible presence of
cancer, the low PSA level would not usually raise suspicions. A PSA
level between 2 and 4 would not warrant a biopsy according to
traditional screening guidelines." Of the 520 men, a total of 75 men (44
African-American and 31 Caucasian) underwent 101 biopsies. The median
age at biopsy was 56 (37 to 73). The median PSA at biopsy was 3.5
(0.4-53.6 ng/ml).
"We found prostate cancers in 45 percent of these
men," said Konski. "Twenty-six percent of these men had a Gleason score
of seven or higher, indicating aggressive cancers. What's more
surprising is that 25 percent of the men who were diagnosed had a PSA of
2.5 or lower." This PSA level falls below the new guidelines adopted
last year by the National Comprehensive Cancer Network and the American
Urological Association, suggesting biopsy when PSA levels exceed 2.5.
The Fox Chase study did not evaluate if earlier
diagnosis of these men increased overall survival.
Source Notes:
Funding for the study was provided by Tessera Inc.
Other authors on the report are Barbara Paul, Rajiv Dhir, Douglas
Landsittel and Moira Hitchens, all of the University of Pittsburgh.
On the Web:
http://cancerres.aacrjournals.org/
http://urology.jhu.edu/robertgetzenberg/index.php
Robert Getzenberg is a paid consultant to and
received an unrestricted research grant from Tessera Inc. Under separate
agreements between the University of Pittsburgh and Tessera and the
Johns Hopkins University and Tessera, Getzenberg is entitled to a share
of royalty payments to the universities on sales of licensed products.
The EPCA test is the subject of the license agreement between the
University of Pittsburgh and Tessera.
The Prostate Cancer Risk Assessment Program offers
education, risk assessment, screening and an opportunity to participate
in innovative prostate cancer research to men who are at an increased
risk of the disease because of their family history or their race. This
unique program is designed for men aged 35 to 69 who have increased risk
of prostate cancer because of family history - a father, brother, or son
with prostate cancer - or because they are African American, with or
without a family history of prostate cancer.
Konski's Fox Chase co-authors include radiation
oncologist Steven J. Feigenberg, M.D., assistant clinical director for
the Prostate Cancer Risk Assessment Program; research nurse Amy Bower,
R.N., M.S.N., O.C.N.; data manager Susan Raysor; research
biostatistician Debra Eisenberg; urologic surgical oncologist Robert G.
Uzzo, M.D.; urologic surgical oncology chief Richard E. Greenberg, M.D.;
radiation oncologist Eric M. Horwitz, M.D.; radiation oncology chairman
Alan Pollack, M.D., Ph.D.; retired radiation oncology chairman Gerald E.
Hanks, M.D.; and Prostate Cancer Risk Assessment Program director
Deborah Watkins Bruner, PhD., along with pathologist Ila Mirchandani,
M.D., of Temple University's Jeanes Hospital.
Fox Chase Cancer Center was founded in 1904 in
Philadelphia as the nation's first cancer hospital. In 1974, Fox Chase
became one of the first institutions designated as a National Cancer
Institute Comprehensive Cancer Center. Fox Chase conducts basic,
clinical, population and translational research; programs of prevention,
detection and treatment of cancer; and community outreach. For more
information about Fox Chase activities, visit the Center's web site at
www.fccc.edu or call 1-888-FOX CHASE.
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