On 8 May an editorial about the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) trial by Fritz H. Schröder and Monique J. Roobol was published in the online version of European Urology, the scientific journal of the European Association of Urology (EAU).
The long-expected final report of the REDUCE trial appeared on April 1, 2010 in the New England Journal of Medicine together with a commentary entitled 'Chemoprevention of prostate cancer' by Dr Patrick Walsh. What were the noteworthy items of the editorial?
* The REDUCE trial, contrary to the Prostate Cancer Prevention Trial (PCPT), is performed in men who would have been candidates for biopsy anyway because of PSA values of 2.5 - 10 ng/ml, making the reduction of the chance of a positive biopsy of 23% clinically relevant.
* The mechanism of dutasteride is not primarily prevention but the inhibition of growth of small, well differentiated cancers as a result of the intracellular reduction of 5a-dihydrotestosterone (DHT). This mechanism which results in the prevention of disease progression is called 'tertiary prevention' and in this setting can be seen as treatment of minimal disease. This effect is seen in spite of the simultaneous, up to 40 times increase in testosterone (T). It remains unclear why the rise in T does not prevent the effect of the reduction in DHT.
* The report indicates a small difference in cardiovascular side effects in disadvantage of dutasteride. The long-term general health effects obviously remain unknown at this time.
* Unanswered issues: is dutasteride useful in reducing unnecessary biopsies and does it help to selectively identify aggressive disease? The reported data show that in men with an indication of periodic biopsies the reduction in the detection of potentially over-diagnosed cancers is 28.2%.
* More detailed analyses are warranted. Extended follow-up to monitor, for example, the outcome of relevant endpoints such as delayed diagnosis of aggressive cancers, progression to metastatic disease and disease-specific mortality in comparison to the control population will be of great scientific value in spite of the unblinding of the trial and should therefore have top priority.
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