Diagnosis of prostate cancer: optimal number of prostate biopsies related to serum prostate-specific antigen and findings on digital rectal examination.

The optimal number of core biopsies of the prostate that are needed for the detection of prostate cancer is unknown. A retrospective review of protocols and charts concerning 1149 transrectal ultrasound examinations with biopsy performed in 1013 patients was undertaken. Cancer detection rate was correlated to findings on digital rectal examination (DRE), serum levels of prostate-specific antigen (PSA) and number of biopsies taken. The cancer detection rate was significantly higher in patients who had five or more cores taken compared to those who had four or less (49% versus 35%, p < 0.05) in patients with serum PSA less than 10 ng/ml and a DRE suspicious of malignancy. The same trend was seen in patients with normal DRE and PSA less than 10 ng/ml (14% versus 8%, p = 0.057), while the detection rate for prostate cancer was unaffected by the number of cores taken if serum PSA was above 10 ng/ml.