Dutasteride is used in the treatment of benign prostate enlargement (BPH).It inhibits conversion of testosterone (T) into the more potent dihydrotestosterone (DHT) to stop prostate (and possibly prostate cancer) growth. DHT regulates the expression of certain genes in the prostate. The pharmacodynamics of DHT reduction in the prostate were never investigated until now, as every measurement would require prostate tissue retrieval, which is medically and ethically unacceptable. A recently developed test is able to quantitatively measure gene expression in prostate-borne cells, in urine sediments after prostate massage. By measuring this gene expression in patients using dutasteride, it has become possible to assess the pharmacodynamics of gene expression reduction, which is representative for the pharmacodynamics of DHT reduction. Repeated prostate tissue sampling has therefore become unnecessary. This newly gained knowledge will lead to a better understanding of the action of dutasteride and will possibly help improve treatment of symptomatic BPH (Benign Prostatic Hyperplasia) and PrCa (Prostate Cancer)in the future.

A randomized, open-label, parallel-group pilot study, to assess the pharmacodynamic effect on dihydrotestosterone regulated gene expression, longitudinally and in a dose dependent manner, of 0.5mg or 3.5mg dutasteride administered orally once daily, for three months in men with symptomatic benign prostatic hyperplasia or during the period between baseline and radical prostatectomy in men with biopsy-proven, clinically localized prostate cancer.

Inclusion criteria:

• Symptomatic BPH, or:

Biopsy proven, localised (cT1 or cT2) prostate cancer scheduled for radical operation

• Able to swallow oral medication

Exclusion criteria:

• Inability to void spontaneously (eg. dependence on catheter etc.)
• History of (prior) prostate cancer Previous prostatic surgery