The clinical utility of transrectal ultrasound and digital rectal examination in the diagnosis of prostate cancer.

The development of high definition transrectal ultrasound probes has led to an increased interest in the ability of transrectal ultrasound of the prostate (TRUS) to assist in the diagnosis and management of prostate cancer. The present study was designed to examine the correlation of TRUS with digital rectal examination (DRE). The study group comprised 471 patients in whom the results of (a) DRE, (b) TRUS, and (c) histology of tissue obtained by transrectal biopsy of the prostate (TB), were all available. In those patients where both TRUS and DRE were negative, but prostate specific antigen (PSA) was greater than 10 micrograms ml-1, six random biopsies were performed. In all other cases the biopsies were TRUS directed to the suspicious lesion. There were 142 cases in whom both DRE and TRUS were negative or only mildly suspicious of malignancy. TB in these cases was positive for cancer in 17 cases (12%). In a further 126 cases, TRUS was positive for cancer, while DRE demonstrated no suspicious nodule. TB was positive in only 17 of these cases (13.5%). Similarly, in the 31 cases in which DRE was positive but TRUS was negative, TB was positive in only three cases (10%). In the 172 cases in whom both DRE and TRUS were positive, 99 biopsies were positive (57.5%). It was concluded from this study that DRE remains the most valuable single examination in the diagnosis of prostate cancer. TRUS increases the sensitivity of DRE if both are positive. When there is a discrepancy between the two examinations, the biopsy yield is low. When both are positive, a high cancer yield is obtained, TRUS having added value in directing the biopsy needle to the suspicious site. TRUS is thus a valuable adjunct to DRE in the diagnosis of prostate cancer.