Optimal sampling sites for repeat prostate biopsy: a recursive partitioning analysis of three-dimensional 26-core systematic biopsy

OBJECTIVES: To explore an optimal combination of sampling sites to detect prostate cancer in a repeat biopsy setting. METHODS: A transrectal ultrasound-guided systematic three-dimensional 26-core biopsy (3D26PBx), a combination of transrectal 12 and transperineal 14 core biopsies, was performed in 235 Japanese men with prior negative biopsy. Using recursive partitioning, we evaluated cancer detection of all possible combinations of sampling sites and selected the combination that provides the highest cancer detection rate at a given number of biopsy cores. RESULTS: Prostate cancer was detected in 87 of the 235 (37%) men. The 3D26PBx improved cancer detection by 89% relative to the conventional transrectal sextant biopsy. Neither Gleason score nor percentage of Gleason 4/5 cancers differed between cancers with and without positive cores within the transrectal sextant-sampling sites. A three-dimensional combination of transrectal and transperineal approaches outperformed either transrectal or transperineal approach alone. Recursive partitioning revealed that a three-dimensional 16-core (transrectal eight cores plus transperineal eight cores) biopsy could detect all the cancers with the minimum number of cores. CONCLUSIONS: We propose a three-dimensional combination of transrectal eight cores taken from the far lateral peripheral zone and the parasagittal base, and transperineal eight cores taken from the anterior and posterior apex and the transition zone as an optimal set of sampling sites for repeat biopsy.