Right now, finasteride, manufactured by Merck & Co., is widely used to shrink the enlarged prostate glands of men with benign prostate hyperplasia and thereby improve symptoms. A lower dose of finasteride was approved by the FDA last year to treat cosmetic, incipient hair loss and is marketed under the brand name Propecia.
Although small, the new USC/Norris study seems especially significant in light of this ongoing trial, researchers say. "Ours are the first data to address the question of whether finasteride prevents disease. The results are not reassuring," Ross says.
In contrast to the NCI study (which is focusing on healthy men), the USC team studied 52 men with elevated blood levels of PSA (prostate specific antigen) whose biopsies showed no signs of prostate cancer. PSA is a protein produced only by prostate cells that doctors use as a broad, though fallible, screen for prostate cancer. Because all of the men in this study had elevated PSA levels, they were considered to have a higher risk of developing prostate cancer than men with normal PSA levels.
Half of the men were treated with finasteride for one year, while the other half received no treatment. At the end of the study, a second biopsy revealed that eight of the 27 men who took the drug had developed tumors, compared to only one of the 25 men in the observation-only group.
To evaluate the drug's ability to block tumor development, Cote, Ross and Skinner tracked key intermediate markers of disease, a novel approach to testing new chemopreventive agents. They measured the participants' blood levels of testosterone, PSA and dihydrotestosterone; they also compared tissue samples from the biopsies at the start of the study to those at the end.
While men in the control group showed no changes in blood levels of PSA,
testosterone or dihydrotestosterone, the treated men's PSA levels dropped by 48%
and dihydrotestosterone leve
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Contact: Eva Emerson or Brenda Maceo
eemerson@hsc.usc.edu
323-442-2830
University of Southern California
1-Aug-1998