Transperineal 3D mapping biopsy of the prostate: an essential tool in selecting patients for focal prostate cancer therapy.

INTRODUCTION: The pathologic literature indicates that 25% of prostate cancer patients have a single tumor without evidence for multifocal disease. Previously published results indicate that a focal cryoablative prostate cancer treatment may provide good cancer control with decreased morbidity. Proper selection of patients who have only unifocal disease, however, is critical for such a management strategy to be successful. In this study, we present our experience with transperineal 3D mapping biopsy used as an additional staging procedure prior to focal prostate cancer therapy.
METHODS: The biopsy method consisted of a transperineal approach carried out under transrectal ultrasound guidance. Samples were taken every 5 mm throughout the volume of the prostate using a brachytherapy grid. Each sample was labeled separately as to its grid location.
RESULTS: One hundred ten patients, all of whom had unilateral disease on transrectal ultrasound (TRUS) biopsies, were restaged using the 3D mapping method prior to focal therapy. The median number of cores taken was 46 (SD +/- 19). Bilateral cancer was demonstrated in 60 patients (55%, all of whom had only unilateral cancer shown on TRUS biopsy. The Gleason score was increased in 25 patients (23%) over the TRUS biopsy. Complications were self-limited and included 9 patients (8%) who required short term indwelling catheter drainage and 2 with hematuria.
CONCLUSIONS: Transperineal 3D mapping biopsy of the prostate is well tolerated and provides superior staging information compared with TRUS biopsy. It should be an essential component in selecting patients for focal prostate cancer therapy.