Transperineal Template Guided Prostate Biopsy Selects Candidates for Active Surveillance--How Many Cores are Enough?

Most prostate cancer active surveillance protocols recommend a confirmatory biopsy within 3 to 6 months of diagnosis. Transperineal template guided biopsy is an approach to improve the detection of high grade prostate cancer. However, to our knowledge the optimal technique is unknown. We evaluated the relative performance of 2 transperineal template guided biopsy approaches.

Institutional review board approved prospective databases at Virginia Mason and University of Michigan were used. Men eligible for active surveillance based on initial 12-core biopsy demonstrating NCCN® guideline low risk prostate cancer were included in study. All men underwent confirmatory transperineal template guided biopsy between 2005 and 2014, and within 6 months of diagnosis. The biopsy technique was based on a 24-core template with 12 anterior and 12 posterior cores or a template based on gland volume with an average of 1 core per cc. Outcome comparisons were made by the chi-square and Fisher exact tests, the Welch t-test and linear regression.

Of the 135 men 46 underwent 24-core biopsy and 89 underwent volume based biopsy (median 62 cores). No statistically significant difference was noted in the prevalence of upgrading (35% vs 29%, p = 0.64) or complications (9% vs 16%, p = 0.38) between the 24-core and volume based groups. The difference in the probability of upgrading by volume based biopsy adjusted for age, prostate specific antigen, prostate volume, clinical stage and number of prior biopsies was -4% (95% CI -24 to 14%, p = 0.63).

A significant difference was not detected in upgrading or morbidity between a 24-core template and a more exhaustive volume based template. A less invasive 24-core transperineal template guided biopsy strategy may suffice to accurately identify men who are appropriate for active surveillance.