Transrectal ultrasound versus digital rectal examination for the staging of carcinoma of the prostate: Results of a prospective, multi-institutional trial

Purpose: We determined the accuracy of transrectal ultrasonography versus digital rectal examination in staging the local extent of biopsy proved carcinoma of the prostate. Materials and Methods: A National Institutes of Health funded network was developed to perform prospective, multi-institutional trials. A total of 386 patients judged by the investigators to be candidates for radical prostatectomy underwent transrectal ultrasonography with recording of data according to a numerical analog for construction of receiver operating characteristic curves. The results of digital rectal examination were similarly recorded. After radical prostatectomy whole mount histology was performed on all surgical specimens, and pathological findings were correlated with preoperative transrectal ultrasound and digital rectal examination results. Results: The calculated area under the curve for transrectal ultrasound in predicting extracapsular tumor extension was 0.69 compared to 0.72 for digital rectal examination (p = 0.64), while that for predicting seminal vesicle invasion was 0.74 and 0.69, respectively (p = 0.36). There was a nonstatistically significant trend for improved accuracy of both examinations as tumor volume increased. Transrectal ultrasound was more accurate for staging posterior cancers than for those in the anterior portion of the prostate. Conclusions: Neither transrectal ultrasound nor digital rectal examination proved to be superior to each other for staging the local extent of prostate cancer. No imaging modality or examination that depends on gross architectural changes is likely to have a high degree of accuracy in detecting microscopic extension of extracapsular tumor frequently observed in radical prostatectomy specimens.