Dutasteride is an inhibitor of the 5 alpha reductase type I and type II enzymes that convert testosterone to DHT, the male hormone that leads to benign prostate growth and drives malignant growth. Dutasteride has been shown to significantly decrease intraprostatic DHT in men with localized prostate cancer, and additionally cause apoptosis and regression of some prostate cancers \[Andriole, 2004a; Andriole, 2004b\]. Furthermore, reduction in tumor volume has also been demonstrated in human prostate tissue \[Iczkowski, 2004\]. Dutasteride is currently indicated to treat symptomatic BPH in men with enlarged prostates, but is also being studied to reduce the risk of prostate cancer in men at risk (elevated PSA and previous negative biopsy). Dutasteride is clinically useful at improving lower urinary tract symptoms (LUTS) in men with clinically-localized prostate cancer and voiding difficulty being treated with single-dose goserelin, TUIP, and interval SI. \[Mitcheson, personal observation\].
