OBJECTIVES: To compare the ability of total prostate (TP) and transition zone (TZ) volume to predict the outcome of a repeat prostate biopsy in patients with serum prostate-specific antigen (PSA) levels of 4 to 10 ng/mL. METHODS: A total of 1137 patients were included and underwent transrectal ultrasound-guided needle sextant and two transition zone biopsies of the prostate. All patients with a prior negative biopsy (benign prostatic tissue) underwent a repeat biopsy after 6 weeks. The TP and TZ volumes of the prostate were measured by transrectal ultrasonography. RESULTS: Of the 1137 patients, prostate cancer was diagnosed in 364 (32%), in 276 (24.2%) after the first biopsy and in 88 (7.7%) after the repeated biopsy. The TP and TZ volumes were larger in the patients with prostate cancer detected on the repeated biopsy (P <0.0001). Using a cutoff for TP volume of less than 20 cm3 and greater than 80 cm3 and for TZ volume of less than 9 cm3 and greater than 41 cm3 would have spared 7.1% and 10% of repeated biopsies, respectively. CONCLUSIONS: The probability for a positive repeat prostate biopsy increases in a logarithmic function for larger prostates, as well as for larger TP and, especially, for larger TZ volumes. The probability of finding prostate cancer on a repeat biopsy in prostates with small (less than 20 cm3) and large (greater than 79 cm3) TP, as well as in small (less than 9.3 cm3) and large (greater than 41 cm3) TZ volumes, was very low. Therefore, a repeat prostate biopsy within 6 weeks is unnecessary. These patients should be followed up by serial PSA determination.
OBJECTIVES: To compare the ability of total prostate (TP) and transition zone (TZ) volume to predict the outcome of a repeat prostate biopsy in patients with serum prostate-specific antigen (PSA) levels of 4 to 10 ng/mL. METHODS: A total of 1137 patients were included and underwent transrectal ultrasound-guided needle sextant and two transition zone biopsies of the prostate. All patients with a prior negative biopsy (benign prostatic tissue) underwent a repeat biopsy after 6 weeks. The TP and TZ volumes of the prostate were measured by transrectal ultrasonography. RESULTS: Of the 1137 patients, prostate cancer was diagnosed in 364 (32%), in 276 (24.2%) after the first biopsy and in 88 (7.7%) after the repeated biopsy. The TP and TZ volumes were larger in the patients with prostate cancer detected on the repeated biopsy (P <0.0001). Using a cutoff for TP volume of less than 20 cm3 and greater than 80 cm3 and for TZ volume of less than 9 cm3 and greater than 41 cm3 would have spared 7.1% and 10% of repeated biopsies, respectively. CONCLUSIONS: The probability for a positive repeat prostate biopsy increases in a logarithmic function for larger prostates, as well as for larger TP and, especially, for larger TZ volumes. The probability of finding prostate cancer on a repeat biopsy in prostates with small (less than 20 cm3) and large (greater than 79 cm3) TP, as well as in small (less than 9.3 cm3) and large (greater than 41 cm3) TZ volumes, was very low. Therefore, a repeat prostate biopsy within 6 weeks is unnecessary. These patients should be followed up by serial PSA determination.