Prostate cancer gene 3 urine assay for prostate cancer in Japanese men undergoing prostate biopsy.

OBJECTIVES: To examine the clinical utility of the prostate cancer gene 3 (PCA3) urine test in predicting prostate cancer in Japanese men undergoing prostate biopsy.

METHOD: The study group included 105 men who underwent extended prostate biopsy based on an elevated serum prostate-specific antigen (PSA). In all cases, the patients' race was Asian. Urine specimens were collected after digital rectal examination, and PCA3 score (PCA3/PSA mRNA) was determined in the urine using the APTIMA PCA3 assay. PCA3 score was investigated for a correlation with serum PSA, prostate volume (PV), PSA density and biopsy outcome.

RESULTS: All urine samples collected were successfully analyzed (i.e. the informative specimen rate was 100%). Biopsy showed prostate cancer in 38 men (36%). The PCA3 score was not associated with serum PSA nor PV. The median PCA3 score in prostate cancer was significantly higher than that in negative biopsy (59.5 vs 14.2 P<0.0001). The probability of prostate cancer was 69% at a PCA3 score of more than 50 and 5% at a PCA3 score of less than 20. On multivariable logistic regression, PSA density (P<0.05) and PCA3 score (P<0.0001) were the independent predictors for prostate cancer. There was no significant difference in AUC between PCA3 score and PSA density. The combination of PCA3 score and PSA density increased the AUC from 0.72 for PSA alone to 0.88.

CONCLUSION: The specificity of the PCA3 urine assay for prostate cancer was excellent in Japanese men undergoing biopsy. PCA3 score could improve the prediction for prostate cancer and help to better select men who might benefit from prostate biopsy.