Prostate cancer is the most common malignancy diagnosed in men in the Western hemisphere. Once early tumors are detected, prognosis is largely unpredictable, and clinicians are currently unable to inform the patient whether his tumour is likely to progress. New criteria to define the aggressive and metastatic potential of prostate cancer are needed, particularly in view of the recent controversies and evidence from North American studies questioning the benefits of radical surgery over observation in early-stage prostatic adenocarci-noma (1 -3 ). Furthermore, even in patients where the disease appears to be confined to the prostate, cancers can be understaged in over 50% of cases, with resulting positive surgical margins, extracapsular extension, and potential treatment failure (4 ).