The Role of Biopsy Core Number in Selecting Prostate Cancer Patients for Active Surveillance

Background: Studies offer wide variations in inclusion criteria for active surveillance (AS) in prostate cancer (PCa), but the role of the biopsy core number has not been thoroughly assessed. Objective: To evaluate the impact of the biopsy core number on the risk of misclassification for AS eligibility. Design, setting, and participants: : This prospective study included 411 men eligible for AS who fulfilled at least one of four of the criteria reported in the literature groupings among a screening cohort of 2917 patients. Intervention: All patients underwent a 21-core biopsy with cores mapped by location and acted as controls of themselves for the analysis of biopsy core number (6-, 12- and 21-core schemes). Radical prostatectomy (RP) was performed in 297 men (72%). Measurements: The number of included patients, PCa extent on biopsy, rate of unfavorable disease in RP specimens, and biochemical recurrence-free survival were compared as a function of (1) the different criteria groupings for AS and (2) the biopsy core number (6, 12, or 21). Results and limitations: Of the 1104 patients with PCa, the proportion eligible for AS ranged from 22.5% to 35.4% based on AS criteria. In men who fulfilled AS criteria only in a 12-core strategy, tumor length and percentage of cancer involvement on biopsy were significantly greater than in those who fulfilled AS criteria in a 21-core scheme. The rate of unfavorable disease on RP specimens was also higher in the former group, from 28.6% to 35.9% relative to AS criteria (p = 0.014, 0.044, and 0.113 in groups 2, 3, and 4, respectively). Conclusions: Men eligible for AS based on a 21-core strategy have cancers with a lower extent of disease on biopsies and a lower risk of unfavorable disease on RP specimens regardless of how AS criteria are defined, compared with men eligible in a 12-core scheme. (C) 2009 European Association of Urology. Published by Elsevier B. V. All rights reserved.