Clinical evaluation of the PCA3 assay in guiding initial biopsy decisions.

PURPOSE We evaluated the clinical utility of the PCA3 assay in guiding initial biopsy decisions in prostate cancer. MATERIALS AND METHODS A European, prospective, multicenter study enrolled men with a serum total prostate specific antigen of 2.5 to 10 ng/ml scheduled for initial biopsy. After digital rectal examination first catch urine was collected. PCA3 scores were determined using the PROGENSA(®) PCA3 assay and compared to biopsy outcome. The diagnostic accuracy of PCA3 was compared to total prostate specific antigen, prostate specific antigen density and %free prostate specific antigen. RESULTS In 516 men the positive biopsy rate was 40%. An increasing PCA3 score corresponded with an increasing probability of a positive biopsy. The mean PCA3 score was higher in men with a positive vs a negative biopsy (69.6 vs 31.0, median 50 vs 18, p <0.0001). The PCA3 score was independent of age, total prostate specific antigen and prostate volume. The PCA3 score (cutoff of 35) had a sensitivity of 64% and specificity of 76%. ROC analysis showed a significantly higher AUC for the PCA3 score vs total prostate specific antigen, prostate specific antigen density and %free prostate specific antigen. The PCA3 score was significantly higher in men with biopsy Gleason score 7 or greater vs less than 7, greater than 33% vs 33% or fewer positive cores and significant vs indolent prostate cancer. Inclusion of PCA3 in multivariable models increased their predictive accuracy by up to 5.5%. CONCLUSIONS The PROGENSA PCA3 assay can aid in guiding biopsy decisions. It is superior to total prostate specific antigen, prostate specific antigen density and %free prostate specific antigen in predicting initial biopsy outcome, and may be indicative of prostate cancer aggressiveness.