(DOWNLOAD) "Assessing the Clinical Impact of Prostate-Specific Antigen Assay Variability and Nonequimolarity: A Simulation Study Based on the Population of the United Kingdom (Cancer Diagnostics)" by Clinical Chemistry " eBook PDF Kindle ePub Free
eBook details
- Title: Assessing the Clinical Impact of Prostate-Specific Antigen Assay Variability and Nonequimolarity: A Simulation Study Based on the Population of the United Kingdom (Cancer Diagnostics)
- Author : Clinical Chemistry
- Release Date : January 01, 2004
- Genre: Chemistry,Books,Science & Nature,
- Pages : * pages
- Size : 222 KB
Description
Prostate-specific antigen (PSA) [4] is the most widely used serum biomarker to differentiate between malignant and benign prostate disease and is currently the subject of numerous large-scale randomized trials to assess its potential as a screening method for early prostate cancer detection (1). PSA circulates in human serum in two main forms, either free ("unbound") or complexed ("bound") (2); complexed PSA refers to the fraction of total PSA (tPSA) that is bound to any of the proteinase inhibitors, whereas free PSA (fPSA) is the fraction not bound to any protein. Generally, tPSA concentrations in healthy men are low (4 [micro]g/L) and are increased in men with prostate disease (3); men with prostate cancer also tend to have a lower fraction of fPSA and a higher fraction of complexed PSA than men with benign disease (4, 5). Assays for the measurement of PSA used by diagnostic laboratories, the majority of which are now commercially available assays, have considerable differences in their epitope recognition, which can lead to significantly different tPSA values for the same serum sample (6, 7). Therefore, samples containing effectively the same amount of tPSA but with different proportions of fPSA can produce very different values for both tPSA and fPSA. These differential response assays are usually referred to as skewed-response or nonequimolar assays. This has led to the development of International Standards for the purposes of assay calibration for both fPSA and tPSA (8).
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