Among men at increased risk of developing prostate cancer, use of Avodart® (dutasteride)—a drug currently used to treat benign prostatic hyperplasia— decreased the risk of prostate cancer by 23%. These results were presented at the 2009 annual meeting of the American Urological Association.

Other than skin cancer, prostate cancer is the most commonly diagnosed type of cancer among men in the United States. Each year, there are approximately 186,000 new diagnoses and more than 28,000 deaths from the disease.

For common types of cancer such as prostate cancer and breast cancer, there is a great deal of research focused on cancer prevention. Researchers are exploring the role of behavioral factors such as diet and exercise, as well as the use of drugs to reduce cancer risk. Cancer prevention efforts are particularly important for those who are at increased risk of developing cancer.

Avodart is a 5-alpha reductase inhibitor. The 5-alpha reductase enzymes convert testosterone to another hormone known as dihydrotestosterone (DHT). DHT is the most potent male hormone in the prostate. Avodart is currently used to treat benign prostatic hyperplasia (BPH); it has not been approved for the treatment or prevention of prostate cancer.

To explore the role of Avodart in prostate cancer prevention, researchers conducted a study known as REDUCE (REduction by DUtasteride of prostate Cancer Events). The study enrolled 8,121 men between the ages of 50 and 75. The men had elevated PSA levels (up to 10 ng/mL) but a negative prostate biopsy.

Men were assigned to receive either Avodart or a placebo. Treatment was given daily for four years.

• Men who received Avodart were 23% less likely to develop prostate cancer than men who received the placebo.
• Among men who developed prostate cancer, the proportion with a high Gleason score (a measure of how abnormal the prostate cancer cells look under the microscope) was similar in the two study groups.
• The most common side effects were erectile dysfunction (9.0% of men in the Avodart group and 5.7% of men in the placebo group); decreased libido (3.3% of men in the Avodart group and 1.6% of men in the placebo group); and breast enlargement (1.9% of men in the Avodart group and 1.0% of men in the placebo group).

These results suggest that Avodart may reduce the risk of prostate cancer in men at high risk of developing the disease.

Reference: GlaxoSmithKline Press release. Large, long-term study shows dutasteride reduced prostate cancer risk in men at increased risk of the disease. Available at: http://www.gsk.com/media/pressreleases/2009/2009_pressrelease_10047.htm Accessed April 28, 2009.

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