Validation of criteria used to predict extraprostatic cancer extension: A tool for use in selecting patients for nerve sparing radical prostatectomy

Purpose: We have previously reported that a prostate biopsy core specimen with a tumor length of at least 7 mm plus any positive basal biopsy core is the best predictor of extraprostatic extension (EPE) in radical prostatectomy (RP) specimens. We present prospectively collected data to validate our results. Materials and Methods: The study included 270 patients who underwent RP for localized prostate cancer between January 2002 and December 2003 by a single surgeon. We correlated side specific biopsy data, pretreatment prostate specific antigen, clinical stage and RP type using pathological specimen data. Results: Mean patient age was 59.6 years and median prostate specific antigen was 8.24 ng/ml. Of the patients 94 (35%) underwent unilateral and 114 (42%) underwent bilateral nerve sparing RP. The overall incidence of EPE was 16%. The incidence of EPE was 33% in patients who met our criteria vs 4.6% in those who did not. Of 538 evaluable sides 7.2% were positive at the surgical margin. The incidence of ipsilateral positive margins was 2.5% when the neurovascular bundle was spared according to our criteria vs 11.8% when the bundle was resected according to criteria. Conclusions: This series validates our finding that a prostate biopsy core with a tumor length of at least 7 mm plus a positive basal biopsy core of any length and tumor grade is predictive of ipsilateral EPE. In the absence of these criteria the incidence of ipsilateral positive margins is low. Thus, these criteria are valuable for predicting EPE and selecting patients for nerve sparing RP.