前立腺全摘除術に対する経直腸的超音波検査と sextant systematic core biopsy の意義と有用性

BACKGROUND: To estimate the usefulness of sextant systematic core biopsy or transrectal ultrasonography (TURS) for performing radical prostatectomy. METHODS: The findings of sextant biopsy and TRUS were compared with 52 step-sectioned specimens obtained from radical prostatectomy. RESULTS: In 34 cases with no influence of hormonal therapy at the time of TRUS and biopsy, sextant systematic core biopsy provided tumor distribution rather precisely. In 33% of the cases who had received hormonal therapy, tumor cells were not detected by this sextant biopsy series. In these cases, majority of residual cancer existed in transition zone, paraurethral or fibromuscular stroma. Six cases showed small adenocarcinoma in only one biopsy tip obtained from sextant biopsy, while 4 cases were revealed well differentiated adenocarcinoma (Gleason score less than 4) by these core biopsies. Comparing with tumor mapping, Gleason score, PSA level and pT stage of the radical prostatectomy specimens, these tumors presented as, not clinically insignificant, but clinically significant prostate cancer. Playing special attention to distraction of normal ultrasound zonal configuration, TRUS detected neurovascular invasion with 94.7% sensitivity, 78.3% positive predictive value and 90. 9% negative predictive value, while seminal vesicle invasion with 75% sensitivity, 50% positive predictive value, 90.9% negative value. CONCLUSION: Sextant biopsy tended to underestimate the tumors located in the transition zone, paraurethral and fibromuscular lesion. Additional or direct biopsies in transition zone are indispensable for accurate diagnosis. Findings of TRUS and distribution of positive core biopsy from sextant biopsy enable to extract stage C prostate cancer providing negative surgical margin.