PSA density as a better predictor of prostate cancer than percent-free PSA in a repeat biopsy.

BACKGROUND The aim of our study was to identify the optimal predictor of prostate cancer among several prostate-specific antigen (PSA) derivatives in repeat prostate biopsy. METHODS We retrospectively assessed the repeat prostate biopsy specimens, obtained between 1999 and 2008, of 212 patients with a total PSA (tPSA) of 4-10 ng/ml and normal digital rectal examination. Using a receiver operating characteristic (ROC) analysis, we assessed the predictive power of tPSA, percent free PSA (f/t PSA), PSA density (PSAD), and PSA velocity (PSAV) for the detection of prostate cancer. RESULTS Repeat prostate biopsy specimens were positive for prostate cancer in the case of 26 patients and negative in the case of 186 patients. The areas under the receiver operating characteristic (ROC) curves for tPSA, f/tPSA, PSAD, and PSAV were 72.7%, 57.9%, 74.4%, and 64.8%, respectively. The ROC curve analysis revealed that PSAD was a better predictor of prostate cancer than f/t PSA. Moreover, when PSAD at an optimal cutoff of 0.18 ng/ml/cc was considered as the predictor, the detection of prostate cancer was found to have a high sensitivity and specificity (77% and 69%, respectively). CONCLUSION In a repeat prostate biopsy, PSAD is superior to f/t PSA as a predictor of prostate cancer. And, by assessing this predictor, an unnecessary repeat biopsy of patients with tPSA of 4-10 ng/ml can be avoided.