Objective: To validate post-transrectal ultrasonography (TRUS) prostate biopsy (bx) urine samples for PCA3 messenger ribonucleic acid testing, including correlation of PCA3 score with concurrent bx findings.
Methods: From July 2008 to July 2010, 2015 patients had urine collected immediately after a TRUS-guided prostate bx. Excluded were men with history of prostate carcinoma (CaP), <6 or ≥24 bx cores, and/or prostate-specific antigen (PSA) level ≥50 ng/mL, resulting in 1909 included men. PCA3 and PSA messenger ribonucleic acid were quantitated using transcription-mediated amplification. A PCA3 score of ≥35 was considered positive.
Results: Mean and median ages were 66 years. Mean and median PSA levels were 6.7 and 5.1 ng/mL, respectively. Bxs were benign in 970 (50.8%), CaP in 726 (38%), high-grade prostatic intraepithelial neoplasia (HGPIN) in 124 (6.5%), and atypical in 89 (4.7%). PCA3 test was informative in 1887 (98.8%) patients. Means ± standard deviations (median) of PCA3 scores for benign, HGPIN, atypical, and CaP were 22.3 ± 27.9 (12.8), 37.6 ± 43.2 (24.1), 35.7 ± 36.2 (25.7), and 46.9 ± 48.1 (31.6; P <.05 benign vs CaP, benign vs HGPIN and atypical, HGPIN and atypical vs CaP). Sensitivity and specificity of PCA3 for CaP were 46.3% and 78.7%, respectively. CaP risk increased with progressively higher PCA3 score ranges from 14.8% for PCA3 <5 to 66.7% for PCA3 >100. Area under the curve (AUC) for the PCA3 receiver operating characteristics was not significantly different in men without prior bx (AUC = 0.716) compared with men with at least 1 prior nonpositive bx (AUC = 0.702).
Conclusion: Post-TRUS bx urine is a valid sample for PCA3 testing. Patients with a negative bx and a positive PCA3 test may have a higher likelihood of unsampled CaP.
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