Analysis of prostate cancer localization toward improved diagnostic accuracy of transperineal prostate biopsy

PURPOSE: Delineating the precise localization of prostate cancer is important in improving the diagnostic accuracy of prostate biopsy. METHODS: In Juntendo University Nerima Hospital, initial 12-core or repeat 16-core biopsies were performed using a transrectal ultrasound guided transperineal prostate biopsy method. We step-sectioned prostates from radical prostatectomy specimens at 5-mm intervals from the urethra to the urinary bladder and designated five regions: the (1) Apex, (2) Apex-Mid, (3) Mid, (4) Mid-Base, and (5) Base. We then mapped prostate cancer localization on eight zones around the urethra for each of those regions. RESULTS: Prostate cancer was detected in 93 cases of 121 cases (76.9%) in the Apex, in 115 cases (95.0%) in the Apex-Mid, in 101 cases (83.5%) in the Mid, in 71 cases (58.7%) in the Mid-Base, and in 23 cases (19.0%) in the Base. In 99.2% of all cases, prostate cancers were detected from the Apex to Mid regions. For this reason, transperineal prostate biopsies have routinely been prioritized in the Apex, Apex-Mid, and Mid regions, while the Base region of the prostate was considered to be of lesser importance. Our analyses of prostate cancer localization revealed a higher rate of cancer in the posterior portion of the Apex, antero-medial and postero-medial portion of the Apex-Mid and antero-medial and postero-lateral portion of the Mid. The transperineal prostate biopsies in our institute performed had a sensitivity of 70.9%, a specificity of 96.6%, a positive predictive value (PPV) of 92.2% and a negative predictive value (NPV) of 85.5%. CONCLUSIONS: The concordance of prostate cancer between prostatectomy specimens and biopsies is comparatively favorable. According to our study, the diagnostic accuracy of transperineal prostate biopsy can be improved in our institute by including the anterior portion of the Apex-Mid and Mid regions in the 12-core biopsy or 16-core biopsy, such that a 4-core biopsy of the anterior portion is included.