Racial Differences in Men with Prostate Cancer Examined

Newswise — African-American men are known to be at greater risk for developing and dying from prostate cancer. A pilot study published in the September issue of the Journal of Urology reports racial differences in the androgenic stimulation of the prostate could be the reason prostate cancer occurs at a younger age and progresses more rapidly in African than Caucasian Americans. James Mohler, MD, Chair, Department of Urologic Oncology at Roswell Park Cancer Institute (RPCI), is the lead author.

"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.