The diagnostic value of PCA3 gene-based analysis of urine sediments after digital rectal examination for prostate cancer in a Chinese population

Prostate cancer gene 3 (PCA3) encodes a prostate-specific mRNA that has shown promise as a prostate cancer (PCa) diagnostic tool and is detectable in prostate cancer cells shedding into urine after digital rectal examination (DRE). In our earlier studies, a tissue test for PCA3 appeared to have greater specificity for PCa. There, we performed a clinical evaluation of PCA3 mRNA assay in urine sediments after DRE enriched with prostate cells in a Chinese population. PCA3 mRNA was detected by real-time fluorescent quantitative reverse transcription–polymerase chain reaction (FQ-RT–PCR) in the urine sediments. PSA mRNA detected also by real-time FQ-RT–PCR was used to confirm the yield of prostate cells in the urine sediments beforehand and normalize PCA3 mRNA signals. The data were summarized in a receiver operating characteristic (ROC) curve to visualize the efficacy of ratio PCA3/PSA mRNA as a marker; sensitivity and specificity were calculated also. We also correlated the ratio PCA3/PSA mRNA to the biopsy results (including the presence or absence of malignancy and the Gleason score of the malignancy cases) and to the bone metastasis to evaluate its clinical value. The PCA3 mRNA expression (PCA3/PSA mRNA) in the PCa group was significantly higher than that in the BPH group. The AUC-ROC was 0.786 (95% CI: 0.683–0.889). When the cutoff value was set as 0.107, the sensitivity and specificity were 62.9% and 90.6%, respectively. The positive predictive value and negative predictive value of the PCA3 urine test was 78.6% and 81.7%, respectively. No significant correlation was found between urine PCA3 expression and Gleason score or bone metastasis. Results indicated the clinical usefulness of the PCA3/PSA mRNA of urine sediments after DRE as a molecular marker in the early diagnosis of prostate cancer, which appears to be highly specific for PCa. As a non-invasive and sample accessible assay, the PCA3/PSA mRNA may therefore be useful as an aid in the diagnosis of PCa.