Prostate biopsy indices: toward efficient use of transrectal ultrasound.

With increasing use of transrectal ultrasonography (TRUS) it becomes important to establish guidelines for its appropriate utilization. Three hundred and twenty-two patients with either an abnormal digital rectal examination (DRE) or prostate-specific antigen (PSA), or both, were evaluated further for cancer by means of prostatic ultrasonography. Two hundred and twenty-five (70%) of these underwent ultrasound-guided biopsy, cancer was detected in 74 (23%), and 33 percent of all biopsy specimens were positive. Thus, the indices of biopsy: TRUS (Bx:T), cancer: TRUS (Ca:T), and cancer: biopsy (Ca:Bx) were 70 percent, 23 percent, and 33 percent, respectively. Comparing these indices with other earlier series (TRUS used less selectively) and with more recent series (TRUS used more selectively), suggest that ratios in the range of biopsy: TRUS of 70 percent to 75 percent, cancer: TRUS of 25 percent to 30 percent, and cancer: biopsy of 30 percent to 40 percent may be expected with appropriate use of this imaging modality.