NEW YORK--Finasteride (Pros-car), currently FDA approved for use in patients with symptomatic benign prostatic hyperplasia (BPH), is also being investigated as a prostate cancer treatment and is showing promise as an agent to prevent prostate cancer by reducing levels of dihydrotestosterone (DHT), Glenn J. Gormley, MD, PhD, said at the first International Conference on Cancer Prevention.
The program was sponsored by Strang Cancer Prevention Center, Cornell University Medical College, and the European School of Oncology.
Dr. Gormley, senior director of clinical research, endocrinology and metabolism, Merck Research Laboratories, was one of the key individuals involved in the introduction of the compound.
He told the audience that a combined National Cancer Institute and Southwest Oncology Group clinical trial is now underway to assess the efficacy and safety of finasteride(Drug information on finasteride) as a prostate cancer preventive. It will be given over a period of about 7 years to some 18,000 men aged 55 to 70 years who have no existing prostate cancer.
Finasteride inhibits 5-alpha-reductase, thereby blocking the conversion of testosterone to the more potent androgen DHT, Dr. Gormley said. "DHT has five to 10 times the affinity for the androgen receptor." He also stressed that "with the 5-alpha-reductase inhibitors, you can remove DHT-mediated functions without interfering with testosterone-mediated ing functions of the body."
This is a very important point in understanding the safety profile of finasteride and how it differs from that of the antiandrogens, which block the binding of all androgens within the cells and produce more of the "castration-like" effect, he said.