ACCURACY OF DIGITAL RECTAL EXAMINATION AND TRANSRECTAL ULTRASONOGRAPHY IN LOCALIZING PROSTATE-CANCER

Not all prostate cancers are sonographically hypoechoic or palpable on digital rectal examination, and suspicious areas on transrectal prostatic ultrasonography or digital rectal examination often are not cancer. We present quadrant biopsy results from a multicenter prostate cancer screening study in which men were evaluated with prostate specific antigen (PSA) and digital rectal examination. If the PSA level was elevated (greater than 4.0 ng./ml., Hybritech Tandem assay) or digital rectal examination was suspicious quadrant biopsies were performed. Biopsy specimens were labeled separately, and histological findings were correlated by quadrant with the findings on ultrasonography and digital rectal examination. Of the 6,630 subjects enrolled into the study 16% were biopsied. Of 1,002 quadrants that were suspicious on digital rectal examination 110 (11%) had cancer, while 308 of 418 quadrants containing cancer (74%) were not suspicious on digital rectal examination. Of 855 quadrants that were sonographically suspicious 153 (18%) had cancer, while 282 of 435 quadrants containing cancer (65%) were not sonographically suspicious. Of 225 patients with cancer 137 (61%) would have been missed if only the exact site of the palpable induration had been biopsied. Of 251 patients with cancer 131 (52%) would have been missed if only the exact site of the hypoechoic lesion had been biopsied. We conclude that digital rectal examination and transrectal ultrasonography have limited accuracy in identifying and localizing prostate cancer. Our study emphasizes the importance of obtaining systematic biopsies if the PSA level is elevated, even in the absence of digital rectal examination or ultrasound anomalies.