A class of drug long used to treat prostate enlargement appears to have benefits for men diagnosed with low-risk, localized prostate cancer – delaying disease progression and reducing patients' anxiety, a Canadian-led international study has found.
The three-year clinical trial enrolled 302 men with the low-risk form of the disease, aged 48 to 82, who were regularly monitored for clinical changes, a treatment option called "active surveillance."
In the randomized-controlled trial, half the participants received the drug dutasteride (brand name Avodart), while the other half got a dummy pill. The men also had biopsies at 18 and 36 months.
The study showed a significant delay in disease progression in the men treated with dutasteride, one of a class of drugs known as 5a-reductase inhibitors. Among those who received the active medication, 38 per cent saw their disease progress, compared to 48 per cent of those in the placebo group.
As well, the final biopsies showed the men treated with the drug were less likely to have cancer detected – 36 per cent compared with 23 per cent on placebo.
"What we found was the men who were randomly allocated to the dutasteride drug were less likely to say, 'I'm out. I can't tolerate the stress of being on surveillance any more,"' said principal investigator Neil Fleshner, head of urology at Toronto's University Health Network.
"And they were also less likely to have a worse pathology report as their subsequent biopsies went forward."
Dr. Fleshner said the study, published online Monday in The Lancet, shows that active surveillance while taking the drug is a safe, effective treatment option for men who often undergo aggressive treatment, despite having a low risk of dying from the disease.
"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," said Dr. Fleshner.
"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," he said, explaining that these drugs work by inhibiting the male sex hormone that causes prostate enlargement.
A small percentage of men in the study reported drug-related side-effects, including difficulty with sexual desire or erections as well as breast tenderness or enlargement. Stopping the drug reverses these side-effects.
Dr. Fleshner said participants were also assessed for cancer-related anxiety and those men given the drug reported feeling much less anxious because their biopsies and PSA levels improved over time. Levels of PSA, or prostate-specific antigen, can indicate the presence of prostate cancer.
"I think it tells us that by using these drugs we can keep men free of unnecessary treatment for longer periods of time," he said. "And I think … hopefully this will improve the acceptance and make more men likely to choose this option.
"So I'm hoping this is going to help doctors and patients adopt this and avoid some of the anxiety and the concern."
The Canadian Cancer Society estimates 25,500 new cases of prostate cancer will be diagnosed this year and about 4,100 men will die from the disease.
The Canadian Press