Prostate cancer gene 3 urine assay cutoff in diagnosis of prostate cancer: a validation study on an Italian patient population undergoing first and repeat biopsy.

Objective: To determine an optimal prostate cancer gene 3 (PCA3) cutoff in predicting prostate cancer in Italian patients undergoing first or repeat biopsy.

Study Design: In this observational multicenter study 1246 men with elevated prostate specific antigen (PSA) and negative digital rectal examination, with prostate biopsy after PCA3 assessment, were divided into two groups submitted to PCA3 testing before or after previous negative biopsies. Ideal PCA3 cutoff was identified using area under the curve of the receiver operating characteristic analysis. Various cutoff values were used to determine the best predictive score. Univariate and multivariate logistic regression models compared age, PSA, free-PSA, and PCA3 score to predict prostate cancer.

Results: PCA3 cutoff 39-50 had the highest accuracy in the repeat biopsy group in which cutoff of 39 could have avoided 51.9% negative repeat biopsies, eventually missing 7.8% of cancers (all low risk); cutoff of 50 would have prevented 56.5% of negative repeat biopsies, missing 29 tumors (10.3%), 5 potentially aggressive. The PCA3 test performed poorly in the first biopsy group.

Conclusion: We confirm the usefulness of PCA3 in Italian men with a previous negative biopsy. We achieved the best performance at a cutoff of 39. PCA3 did not perform better than PSA in non-biopsy-selected men.