For men diagnosed with low-risk, localized prostate cancer, being treated with the drug dutasteride ("Avodart") delays disease progression and initiating active treatment, and also reduces anxiety, show the results of a three-year international clinical trial led by Dr. Neil Fleshner, Head of the Division of Urology, University Health Network (UHN).
The findings are published online today in The Lancet. "The results prove that using active surveillance plus dutasteride is a viable, safe and effective treatment option for men who often undergo aggressive local treatment despite low risk of dying from the disease," says Dr. Fleshner, a surgical oncologist in UHN's Princess Margaret Cancer Program and Professor of Surgery at the University of Toronto. Dr. Fleshner also holds the Love Chair in Prostate Cancer Prevention Research.
"This is very good news for men with low-risk disease because aggressive treatment can have a major impact on their quality of life, with risks of impotence and incontinence," says Dr. Fleshner.
The three-year clinical trial enrolled 302 men between the ages of 48 and 82 diagnosed with low-risk localized prostate cancer and regularly monitored for clinical changes -- a treatment option called "active surveillance." In the trial -- known as REDEEM (REduction by Dutasteride of clinical progression Events in Expectant Management of prostate cancer) -- participants were randomized 1:1 to receive dutasteride or a matching placebo daily. The men also underwent biopsies at 1.5 and three years.
The study showed a significant delay in disease progression in the men treated with dutasteride -- 38% compared with 48% who received the placebo. As well, the final biopsies showed the men treated with the drug were less likely to have cancer detected -- 36% compared with 23%.
"This is the first study to show that a 5a-reductase inhibitor such as dutasteride reduces the need for aggressive treatment in low-risk disease," says Dr. Fleshner. "The drug, currently commonly used to treat enlarged prostate, works by inhibiting the male sex hormone that causes the enlargement in the first place."
Dr. Fleshner says a small percentage of men reported drug-related side effects including sexual difficulty with either desire or erections (5%), or breast tenderness or enlargement (3%). "It's important to realize that these drugs have been around for almost 20 years in clinical practice to treat enlarged prostates and so we have a wealth of knowledge about their side effects, which are reversible if the drug is stopped."
Participants were also assessed for cancer-related anxiety and the men on dutasteride reported feeling much less anxious because their biopsies and PSA values improved, adds Dr. Fleshner. (PSA -- or prostate-specific antigen -- is a blood test used to help diagnose prostate cancer.)
The Canadian Cancer Society estimates 25,500 new cases of prostate cancer will be diagnosed this year and that 4,100 men will die from the disease.
The clinical research was funded by GlaxoSmithKline. Dr. Fleshner is affiliated with The Campbell Family Cancer Research Institute at PMH and his research is also supported by The Princess Margaret Hospital Foundation.
Princess Margaret Hospital and Ontario Cancer Institute, the hospital's research arm, have achieved an international reputation as global leaders in the fight against cancer. Princess Margaret Hospital is a member of the University Health Network, which also includes Toronto General Hospital, Toronto Western Hospital and Toronto Rehabilitation Institute. All are research hospitals affiliated with the University of Toronto. For more information, go to www.uhn.ca
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