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Limitations of transperineal ultrasound-guided prostate biopsies
1Department of Urology, Stanford University Medical Center, California, USA.
Objectives:
Screening and diagnosing prostate cancer in men who have undergone abdominoperineal resection (APR) poses a diagnostic challenge. Transperineal ultrasound is an effective imaging technique, but the sensitivity of transperineal needle biopsy under ultrasound guidance has not been evaluated. We compared the results of transrectal ultrasound-guided (TRUS) biopsies and transperineal ultrasound-guided (TPUS) biopsies obtained from patients with known prostate cancer, to evaluate the accuracy of TPUS prostate biopsies.
Methods:
Twenty patients with prostate cancer diagnosed by TRUS-guided biopsies were studied. Immediately before radical prostatectomy, TPUS was performed in the lithotomy position and six TPUS-guided biopsies were obtained. Routine sextant TRUS-guided biopsies were then obtained. Finally, radical retropubic prostatectomy was performed and the results of both biopsy sets were compared with the pathologic features of the surgical specimen.
Results:
All 20 prostates contained adenocarcinoma. The prostate was well visualized with TPUS and TRUS in all cases. TPUS-guided biopsies detected cancer in only 2 of the 20 specimens, yielding a sensitivity of 10%. On the same specimens, TRUS-guided biopsies were positive in 13 of 20 cases, a sensitivity of 65%. Cancers detected by TPUS-guided biopsies tended to have a higher volume, higher Gleason grade, and higher prostate-specific antigen level than those not detected by TPUS-guided biopsies.
Conclusions:
TPUS-guided sextant biopsies are less accurate than TRUS-guided sextant biopsies in detecting prostate cancer, even in the hands of experienced ultrasonographers. The limitations of TPUS-guided needle biopsies emphasize the importance of screening for prostate cancer before APR.