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Eur Urol. 2010 Nov;58(5):727-32. doi: 10.1016/j.eururo.2010.06.038. Epub 2010 Jul 3.

External validation of urinary PCA3-based nomograms to individually predict prostate biopsy outcome.

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  • 1Department of Urology, Medical University Graz, Austria. marco.auprich@medunigraz.at

Abstract

BACKGROUND:

Prior to safely adopting risk stratification tools, their performance must be tested in an external patient cohort.

OBJECTIVE:

To assess accuracy and generalizability of previously reported, internally validated, prebiopsy prostate cancer antigen 3 (PCA3) gene-based nomograms when applied to a large, external, European cohort of men at risk of prostate cancer (PCa).

DESIGN, SETTING, AND PARTICIPANTS:

Biopsy data, including urinary PCA3 score, were available for 621 men at risk of PCa who were participating in a European multi-institutional study.

INTERVENTION:

All patients underwent a ≥10-core prostate biopsy. Biopsy indication was based on suspicious digital rectal examination, persistently elevated prostate-specific antigen level (2.5-10 ng/ml) and/or suspicious histology (atypical small acinar proliferation of the prostate, >/= two cores affected by high-grade prostatic intraepithelial neoplasia in first set of biopsies).

MEASUREMENTS:

PCA3 scores were assessed using the Progensa assay (Gen-Probe Inc, San Diego, CA, USA). According to the previously reported nomograms, different PCA3 score codings were used. The probability of a positive biopsy was calculated using previously published logistic regression coefficients. Predicted outcomes were compared to the actual biopsy results. Accuracy was calculated using the area under the curve as a measure of discrimination; calibration was explored graphically.

RESULTS AND LIMITATIONS:

Biopsy-confirmed PCa was detected in 255 (41.1%) men. Median PCA3 score of biopsy-negative versus biopsy-positive men was 20 versus 48 in the total cohort, 17 versus 47 at initial biopsy, and 37 versus 53 at repeat biopsy (all p≤0.002). External validation of all four previously reported PCA3-based nomograms demonstrated equally high accuracy (0.73-0.75) and excellent calibration. The main limitations of the study reside in its early detection setting, referral scenario, and participation of only tertiary-care centers.

CONCLUSIONS:

In accordance with the original publication, previously developed PCA3-based nomograms achieved high accuracy and sufficient calibration. These novel nomograms represent robust tools and are thus generalizable to European men at risk of harboring PCa. Consequently, in presence of a PCA3 score, these nomograms may be safely used to assist clinicians when prostate biopsy is contemplated.

Copyright © 2010 European Association of Urology. Published by Elsevier B.V. All rights reserved.

PMID:
20619529
[PubMed - indexed for MEDLINE]
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