At the 2009 annual meeting of the American Urological Association (AUA) in Chicago, the results of a randomised clinical trial presented there show that treatment with the … 5-alpha reductase inhibitor dutasteride lowers the risk of prostate cancer in men with elevated PSA levels.
Dutasteride was the second 5-alpha-reductase inhibitor, after finasteride, to be introduced for the treatment of benign prostatic hyperplasia (BPH). Both drugs inhibit the conversion of testosterone into dihydrotestosterone. This is the strongest androgen that leads to both benign enlargement of the prostate and is an important growth factor for malignant cells in the prostate.
In the Prostate Cancer Prevention Trail (PCPT), a decrease in prostate cancer cases was shown as early as 2003 in over 18000 men over 55 years of age taking finasteride (24% to 18%). The simultaneous increase in more aggressive forms of cancer is considered by statisticians to be an “artefact” and not significant.
But it was only earlier this year that US professional societies decided to recommend finasteride (Proscar) for the prevention of prostate cancer – on the condition that doctors also make patients aware of the disadvantages of the therapy, which include erectile dysfunction, loss of libido and gynaecomastia. Most patients are therefore likely to see an additional benefit in cancer prevention if they have to take the drug anyway to treat benign prostate enlargement with difficult urination.
The results of a similar study for dutasteride (Avodart) are now available. The Reduction by Dutasteride of Prostate Cancer Events or REDUCE study involved 8,121 men aged 55 to 75. After two years, 17.2 per cent of the men in the placebo arm had prostate cancer compared to 13.4 per cent on dutasteride. After four years, prostate cancer was detected in another 11.8 per cent in the placebo arm versus another 9.1 per cent on dutasteride.
The expert does not necessarily believe that dutasteride can prevent cancer growth; it is more likely that the growth of existing tumours is reduced and that the men therefore develop the cancer later.
Of course, the authors had also tested whether therapy with dutasteride led to an increased incidence of aggressive forms of prostate cancer. This was not the case. The frequency of tumours with a Gleason score of 7 to 10 was 6.8 percent under placebo and 6.7 percent under dutasteride. Tumours with Gleason scores 8 to 10 were observed more frequently in the dutasteride arm (0.9 per cent) than in the placebo arm (0.6 per cent). According to the manufacturer, the most common side effects were erectile dysfunction (9.0 vs. 5.7 per cent), loss of libido (3.3 vs. 1.6 per cent) and gynaecomastia (1.9 vs. 1.0 per cent).
Comment by Dr Keul: A very interesting study that can certainly be applied in daily practice.
Pat Walsh from Johns Hopkins Hospital in Baltimore (he is the “Pope” for the surgical therapy of prostate cancer and Johns Hopkins Hospital has been number one in the US ranking for years), however, points out that by artificially lowering the PSA value, the patient is lulled into a false sense of security. Forms of prostate cancer that do not pose a risk to the patient per se could be reduced by these measures. However, therapy with dudasteride or finasteride cannot prevent cancer.
Translated with www.DeepL.com/Translator (free version)