20-25% lower concentrations of total and free prostate-specific antigen (PSA) after calibration of PSA assays to the WHO reference materials - Analysis of 1098 patients in four centers
January 2009
Article
Aim: To examine the potential clinical implications of the recalibration of total prostate-specific antigen (PSA) and free PSA (fPSA) assays to the World Health Organization (WHO) standard materials. Material and methods: Data from 1098 patients with or without clinically detected prostate cancer (PCa) from four independent cohort studies were compared using commercial assays calibrated to the traditional Hybritech® PSA (PSA-Hyb) and fPSA (fPSA-Hyb) standards and to the WHO 96/670 (PSA-WHO) and 96/668 (fPSA-WHO) standards. The Access® Immunoassay System (Beckman Coulter, Inc.) was used in all studies. Results: All studies showed 20% to 25% lower PSA and fPSA test results with the WHO-standardized assays. No significant change in %fPSA (fPSA/ PSA × 100) was observed. Continuing to use the traditional clinical PSA cutoffs obtained with the Hybritech standard after changing to the PSA-WHO standard could result in up to one-third of prostate cancer cases being missed. Conclusions: Manufacturers should fully inform laboratories about a calibration change and its clinical impact. Laboratory reports for PSA measurements should indicate the assay's manufacturer and which calibration standard was used to avoid misleading information concerning PCa risk.
- article
- human
- male
- metabolism
- methodology
- major clinical study
- controlled study
- prostate cancer
- unclassified drug
- cohort analysis
- cancer diagnosis
- human tissue
- blood
- standard
- world health organization
- laboratory test
- prostate specific antigen
- reproducibility
- reference value
- antigen specificity
- biosynthesis
- immunoassay
- prostate biopsy
- prostate tumor
- diagnosis
- antigen detection
- clinical chemistry
- calibration
- free prostate specific antigen
- measurement and analysis
