by
JACQUELINE STRAX
PSA Rising, New York, September 4, 2003 -- African-American men are
at higher risk for developing and dying from prostate
cancer than white men and most African men. A pilot
study published in the September issue of the Journal
of Urology says one reason for this could be racial differences in
impact of male hormones (androgens) that stimulate the
prostate. Such differences, if they exist, could explain why prostate
cancer occurs at a relatively young age in African American men and progresses
more rapidly. James Mohler, MD, leadign researcher at Roswell Park
Park Cancer Institute (RPCI ), took charge of this study.
"This is the first study to compare the differences in androgen receptor protein expression between African and Caucasian Americans," said Dr. Mohler. "The
over-expression of the androgen receptor protein by the prostate cancers
of African-American men may help to explain why African-Americans suffer
such disproportionately high death rates from prostate cancer compared
to Caucasian Americans."
This initial study measured and compared androgen receptor protein expression in benign and malignant prostate tissue from 25 African and 25 Caucasian Americans. Androgen receptor protein expression was 22% higher in the benign prostate tissue and 81% higher in the prostate cancer tissue of African compared to Caucasian Americans. Androgens are the male hormones responsible for development of male characteristics such as facial and body hair, baldness, and muscle development and the development of the male sex organs including the prostate.
All the patients in the study had undergone radical prostatectomy
for clinically localized prostate cancer. Although African-Americans
had higher serum PSA levels, the pathology of their prostate cancers
revealed no differences in Gleason grade or stage, the most important
indicators of outcome. Racial differences in AR protein expression
were measured using image analysis results and visual analysis and
compared between races and with prostate cancer characteristics such
as Gleason grade, tumor stage and serum PSA.
"This study demonstrates that underlying tumor biology may account for the disparity in prostate cancer outcome by race," said Dr. Mohler. "While it is true that many African-Americans present more often with advanced prostate cancer in part due to more limited access to health care as a result of socioeconomic status, this study proves genetic differences also may account for some of these disparities. Our next step is to analyze the androgen receptor levels in a larger group of men to confirm these findings. If these findings are confirmed, we will have uncovered the first significant biologic difference between races that may allow us to understand better why prostate cancer is more aggressive in African-Americans."
"Understanding why some groups of men are at greater risk of developing prostate cancer is of critical importance," said Donald Trump, MD, Senior Vice President of Clinical Research and Chair of the Department of Medicine, RPCI. "Studies such as Dr. Mohler's offer new insights which may allow us to better target our approaches to detection, prevention and therapy of prostate cancer and are a major component of the prostate cancer research program at Roswell Park."
In the United States an estimated 220,900 new cases of prostate cancer will be diagnosed and 28,900 deaths will occur in 2003. The most common cancer in men, prostate cancer is the second leading cause of cancer death. In men younger than 65 years of age, the prostate cancer death rates for African-Americans are three times that of Caucasian Americans.
Roswell Park Cancer Institute, founded in 1898, is the nation's first
cancer research, treatment and education center and is the only National
Cancer Institute-designated comprehensive cancer center in Upstate
New York. For more information, visit RPCI's website at http://www.roswellpark.org.
Source: Roswell Park Cancer Institute.
Abstract of published article:
J Urol. 2003 Sep;170(3):990-3. Racial
differences in androgen receptor protein expression in men with clinically
localized prostate cancer.Gaston KE, Kim D, Singh S, Ford OH 3rd, Mohler JL. Division of Urology, Department of Surgery, University of North Carolina, Chapel Hill, NC 27599, USA.
