A multicenter evaluation of the PCA3 molecular urine test: Pre-analytical effects, analytical performance, and diagnostic accuracy

Background: Measurement of prostate cancer gene 3 (PCA3) mRNA normalized to prostate-specific antigen (PSA) mRNA in urine has been proposed as a marker for prostate cancer. Methods: We investigated pre-analytical effects, analytical performance, and diagnostic accuracy of a quantitative assay for PCA3. Results: Urine specimens collected without prostate manipulation demonstrated low informative rates. However, specimens collected following digital rectal examinations of 3 or 8 strokes per prostate lobe demonstrated informative rates > 94%. Across all urine specimen types, median PCA3 results did not show statistically significant differences (P > 0.8). Measurements of controls of known mRNA content demonstrated percent recoveries of 100 ± 15% for both PCA3 and PSA mRNAs. PCA3 mRNA total, intra-assay, inter-assay, and inter-site CVs were ≤ 17.1%, ≤ 14.0%, ≤ 9.9%, and ≤ 3.2%, respectively. Corresponding CVs for PSA mRNA assay were ≤ 11.5%, ≤ 8.6%, ≤ 7.9%, and ≤ 8.3%. Blinded assay of urines from 72 men with known prostate biopsy outcomes yielded areas under the curve from receiver-operating characteristic analysis of 0.7 at both research sites. Deming regression of individual PCA3 results between sites yielded slope = 0.94, intercept = 0.48, R = 0.9677 (P < 0.0001). Conclusions: The PCA3 assay is insensitive to pre-analytical factors, performs well analytically and correctly classifies a high percent of subjects with known prostate cancer status across research sites.