Failure of Focal Prostate Cancer on Biopsy to Predict Focal Prostate Cancer: The Importance of Prevalence

PURPOSE: We investigated whether the reported correlation between focal prostate cancer on biopsy and the presence of clinically insignificant cancer applies to men with an elevated serum prostate specific antigen level or a positive biopsy from an area of palpable abnormality. MATERIALS AND METHODS: A total of 33 men with these findings and focal cancer on biopsy underwent radical perineal prostatectomy, with step-section pathological analysis of all specimens and volume determination of all stage pT2a tumors. RESULTS: Pathological examination revealed that 17 tumors (52%) were stage T3, 10 (30%) stage T2b to c and 6 (18%) stage T2a, with 4 (12%) significant (volumes 0.8 to 1.2 ml.) and 2 (6%) insignificant (volumes 0.1 and 0.3 ml.) neoplasms. Thus, focal prostate cancer on biopsy correlated with significant cancer in 94% of the cases. CONCLUSIONS: In patients with another variable controlling for a high prevalence of significant prostate cancer, the focal nature of a positive biopsy probably reflects only sampling limitations and should not influence treatment. To restrict prostate biopsy to men with a high prevalence of significant cancer, targeted area biopsy alone must replace sextant biopsy in men with a palpable prostatic abnormality but a normal prostate specific antigen level.