Objectives: The optimal biopsy strategy for the detection of prostate cancer still needs to be established, since a considerable proportion of clinically significant cancers remains undiagnosed on routine sextant transrectal biopsy. To assess the efficacy of transperineal biopsy to detect prostate cancer, we compared this approach to systematic sextant transrectal biopsy in a simulation experiment.
Methods: Ultrasound-guided sextant transverse (transrectal) biopsy and subsequent sextant longitudinal (transperineal) biopsy were performed on 40 radical prostatectomy specimens of patients with (transrectal) biopsy-detected prostate cancer. Conditions were simulative and may not be completely analogous to clinical settings. Ultrasound-determined prostate volume, biopsy tumor involvement, number of cores with cancer, and tumor volume were determined. Detailed mapping of radical prostatectomy specimens provided insight into the representativeness of the biopsy techniques.
Results: Of 40 cancers, 33 (82.5%) were redetected by the transperineal approach; 29 (72.5%) were detected by repeated transrectal biopsies. For both approaches, the tumor volume of the undiagnosed cancers was significantly smaller (P <0.01) and the prostate volume was significantly larger (P <0.01) than in the redetected ones. Between the two approaches, no difference was found for either of the variables determined in the redetected cancers. Prostate maps clarified that transperineal undiagnosed tumors were either small (0.2 cm(3) or less) or notably located at the prostatic base.
Conclusions: The biopsy procedure in which the biopsy needles enter the prostate at the apex for a longitudinal direction may efficiently sample the prostatic peripheral zone. Since the experiment was artificial in design, caution should be observed in extrapolating these results to patient settings.