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

Sokoll LJ, Ellis W, Lange P, Noteboom J, Elliott DJ, Deras IL, Blase A, Koo S, Sarno M, Rittenhouse H, Groskopf J, Vessella RL. Clinica Chimica Acta 2008;289:1-6

• This study evaluated the pre-analytical effects, analytical performance and diagnostic accuracy of the Prostate CAncer gene 3 (PCA3) Assay.
• It shows that the informative rate for urine specimens collected after a 3-stroke/lobe digital rectal examination (DRE) is high (96.7%) compared to that without a DRE (75.9%: Figure). This means that most urine samples collected after a DRE have enough prostate cells for adequate analysis and that very few patients will have to return to their physician to provide another urine specimen.
• If an informative/valid sample is obtained, the median PCA3 Score is independent of specimen type (i.e. of first morning void, pre-DRE void or post-DRE void) and DRE procedure (i.e. no DRE, 3-stroke/lobe DRE or 8-stroke/lobe DRE: Figure).
• Precision evaluations of PCA3 mRNA indicate total, intra-assay, inter-assay and inter-site variations of ≤ 17.1%, ≤ 14.0%, ≤ 9.9% and ≤ 3.2%, respectively, which is in line with that demonstrated previously¹

1) Groskopf J, et al. APTIMA PCA3 molecular urine test: development of a method to aid in the diagnosis of prostate cancer. Clin Chem 2006;52:1089-95

Reviewed by

Prof. J. Schalken

Editorial comment

In this manuscript an important practical question hovering around the PCA3 test is addressed, namely is a DRE needed for a PCA3 test and secondly does the variation in DRE change the result. The authors show that a DRE needs to be performed, since otherwise in an unacceptable high percentage of specimens not enough cells are retrieved to get a test result. The extent of DRE does not affect the results, which is explained by the fact that in the PCA3 score, the amount of PSA mRNA is used to normalize for cell yield. This was anticipated and proves to have been a good choice.

In summary a normal DRE as described is sufficient to get a PCA3 test result.

More information: http://www.ncbi.nlm.nih.gov/pubmed/