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News » Filed under: Prostate Cancer

Drug May Lower Prostate Cancer Risk, But Cause Other Problems

Article date: April 1, 2010

By: Rebecca V. Snowden

Dutasteride (Avodart), a member of a class of drugs known as 5 alpha-reductase inhibitors, may reduce prostate cancer risk in some men by as much as 23%, according to a new study published in The New England Journal of Medicine. However, taking the drug may also increase a man's risk for cardiovascular problems and of developing prostate cancers that are more likely to grow and spread, the study showed.

Prostate cancer prevention

About 1 man in 6 will be diagnosed with prostate cancer during his lifetime, and many of those cancers will be found with early detection tests such as the prostate-specific antigen (PSA) blood test. While more and more men are surviving the disease, many will have to cope with the unpleasant side effects of prostate cancer treatment, such as incontinence and impotence. Researchers hope to find ways to prevent men from getting the disease in the first place.

Enter 5 alpha-reductase inhibitors, such as finasteride (Proscar) and dutasteride (Avodart). Both drugs work by lowering the body's level of the male hormone DHT. Because male hormones spur prostate cancer growth, lowering them may lower a man's risk of developing the disease. The drugs are also currently used to treat men with enlarged prostates (a condition known as benign prostatic hyperplasia) to help them urinate freely.

In the Prostate Cancer Prevention Trial, from 2003, researchers showed that taking finasteride could lower a man's chance of prostate cancer by 25%, although the results were not clear-cut. This study looked at the possible benefits of taking dutasteride, which is similar to finasteride.

What this study found

In this study, called Reduction by Dutasteride of Prostate Cancer Events (or REDUCE), researchers enrolled 6729 men considered to be at high risk for prostate cancer (they had high PSA levels but negative prostate cancer biopsies) and randomly assigned them to 2 groups: one group (3305 men) received dutasteride, the other (3424 men) a placebo. The men were followed for 4 years. Among the men taking dutasteride, 659 were later diagnosed with prostate cancer, compared to 859 in the placebo group. Dutasteride was most effective at reducing the risk of medium-grade tumors, defined as 5-6 on the Gleason scale, a measure of a tumor's aggressiveness.

"Dutasteride may potentially offer many thousands of men a way to reduce their risk of being diagnosed with prostate cancer," said the study's lead author Gerald Andriole, MD, chief of urologic surgery at Washington University School of Medicine in St. Louis. "This means more men could avoid unnecessary treatment for prostate cancer along with the costs and harmful side effects that can occur with treatment."

However, men who took dutasteride were much more likely to be diagnosed with higher-grade prostate cancers, defined by Gleason scores in the 8-10 range, compared to the placebo group. Also, men taking dutasteride had more heart problems; they were also more likely to report lowered sexual desire and impotence, side effects also seen among men taking finasteride.

"Similar to earlier findings associated with the use of finasteride in the Prostate Cancer Prevention Trial, the current study demonstrates that 5-alpha reductase inhibitors represent a double-edged sword in the realm of prostate cancer prevention," says Durado D. Brooks, MD American Cancer Society director of prostate and colorectal cancer. "Both studies documented an overall reduction in the risk of developing prostate cancers among men in the treatment groups. This finding was, however, tempered by an increased likelihood of detecting high-risk tumors in men who were treated with each of these medications."

Should you take dutasteride?

The results of these studies may become clearer over the next few years, but at this time, doctors don't agree on whether taking a 5 alpha-reductase inhibitor is a good thing.

"These findings further illustrate the challenges of presenting simple messages to men around prostate cancer risk and risk reduction, and reinforce the importance of providing sufficient information to allow men to make an informed decision," said Brooks.

"The American Cancer Society and other groups recommend men thinking about taking these drugs to reduce their risk of prostate cancer should discuss it with their doctors," he said.

In March, the American Cancer Society issued revised prostate cancer screening guidelines encouraging men to discuss the benefits and risks of prostate cancer screening with their doctors.

For more information on this topic, see Prostate Cancer: Early Detection.

This study was co-authored by Otis W. Brawley, MD, American Cancer Society chief medical officer.

Citation: "Effect of Dutasteride on the Risk of Prostate Cancer." Published in the April 1, 2010, New England Journal of Medicine (Vol. 362, No. 13:1192-1202). First author: Gerald L. Andriole, M.D., Chief of Urologic Surgery at Washington University School of Medicine, St. Louis.

 Reviewed by: Members of the ACS Medical Content Staff

ACS News Center stories are provided as a source of cancer-related news and are not intended to be used as press releases.

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