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Background: Prostate cancer antigen 3 (PCA3) is considered to be prostate cancer (PCa) specific and highly overexpressed in cancer. Therefore a high PCA3 score should result in a high positive predictive value (PPV) and specificity for a positive biopsy., Objective: Our aim was to reevaluate, retest PCA3, and rebiopsy men with an initial PCA3 ≥ 100 and no PCa detected and compare the results with a random cohort of men with an initial PCA3<100., Design, Setting, and Participants: We invited men 63-75 yr of age with a PCA3 ≥100 for retesting and a control group with an initial PCA3 < 100 to participate in the European Randomized Study of Screening for Prostate Cancer, section Rotterdam., Interventions: Blood and urine sampling were used to determine prostate-specific antigen (PSA) and PCA3. Prostate biopsies were performed if the PSA was ≥2.5 ng/ml and/or the PCA3 score was ≥ 35., Measurements: We correlated the initial and reevaluated PCA3 scores. Our assessment of the PPV after rebiopsy was based on the newly determined PCA3 score., Results and Limitations: After a mean study period of 19 mo, more cases of PCa were detected in rebiopsied men with initial PCA3 scores ≥ 100 than in the controls with PCA3 scores < 100 (30.0% vs 18.8%). Combining initial and rebiopsy data resulted in a PPV of 52.2% in men with PCA3 ≥ 100. Over time, changes in PSA and PCA3 levels were quite different., Conclusions: In spite of our rescreened population, PPV and specificity were comparable with all reported studies of men with PCA3 scores ≥ 100. These findings do not explain why these PCA3 scores were excessively high in spite of the absence of biopsy-detectable PCa., (Copyright © 2010 European Association of Urology. Published by Elsevier B.V. All rights reserved.)

Purpose: To improve the specificity in prostate cancer diagnosis and to prevent unnecessary prostate biopsies, especially in the serum prostate-specific antigen (PSA) "gray zone" between 3 and 15 ng/mL, the implementation of prostate cancer-specific markers is urgently needed. The recently discovered prostate cancer antigen 3 (PCA3) is such a promising prostate cancer marker. In a previous single institution study, the PCA3 urine test clearly proved to be of diagnostic value. Therefore, the diagnostic performance of the PCA3 urine test was validated in a multicenter study., Experimental Design: The first voided urine after digital rectal examination was collected from a total of 583 men with serum PSA levels between 3 and 15 ng/mL who were to undergo prostate biopsies. We determined the PCA3 score in these samples and correlated the results with the results of the prostate biopsies., Results: A total of 534 men (92%) had an informative sample. The area under the receiver-operating characteristic curve, a measure of the diagnostic accuracy of a test, was 0.66 for the PCA3 urine test and 0.57 for serum PSA. The sensitivity for the PCA3 urine test was 65%, the specificity was 66% (versus 47% for serum PSA), and the negative predictive value was 80%., Conclusions: In this multicenter study, we validated the diagnostic performance of the PCA3 urine test in the largest group studied thus far using a PCA3 gene-based test. This study shows that the PCA3 urine test, when used as a reflex test, can improve the specificity in prostate cancer diagnosis and could prevent many unnecessary prostate biopsies.