Significance of the Percentage of Prostate Needle Biopsy Cores with Cancer as a Predictor of Disease Extension in Radical Prostatectomy Specimens in Japanese Men

Objectives: To evaluate the significance of the percent of positive biopsy cores (PPBC) with cancer, which has been shown to be one of the most useful predictors of prostate cancer extension in patients undergoing radical prostatectomy. Materials and methods: This study included 120 patients who underwent radical prostatectomy for prostate cancer without any neoadjuvant therapies. All of these patients were diagnosed by random prostate biopsy targeting 8 cores; that is, standard sextant cores and 2 additional cores from the bilateral anterior lateral horns. We evaluated the appropriate cut-off points of PPBC for predicting disease extension according to the number of biopsy cores. Based on these criteria, multivariate analysis was then performed to determine whether PPBC could be an independent factor differentiating organ-confined disease from extraprostatic disease. Results: The most suitable PPBC cut-off value using findings targeting 8 cores for predicting disease extension was 37.5%. If PPBC was calculated based on the outcome of standard sextant cores alone, it is most appropriate to use 33.3% as the cut-off point. Multivariate analysis showed that PPBC calculated based on the standard sextant cores and percent of cancer in the biopsy set could be used as independent factors predicting disease extension irrespective of other biopsy-associated factors. Conclusions: For predicting disease extension, it may be useful to calculate PPBC based on the outcomes of standard sextant biopsy cores alone even if additional cores were taken, and that PPBC calculated in such a way may be the strongest preoperative predictor of prostate cancer extension in Japanese men scheduled for radical prostatectomy.