1
|
Mione R, Barioli P, Barichello M, Zattoni F, Prayer-Galetti T, Plebani M, Aimo G, Terrone C, Manferrari F, Madeddu G, Caberlotto L, Fandella A, Pianon C, Vianello L, Gion M. Prostate Cancer Probability after Total PSA and Percent Free PSA Determination. Int J Biol Markers 2018; 13:77-86. [PMID: 9803355 DOI: 10.1177/172460089801300203] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The percent free PSA value is a promising diagnostic tool for prostate cancer. However, its actual role has not yet been established because of the widely diverging sensitivity and specificity values. This could depend at least in part on analytical difficulties, since the free PSA concentration is much lower than that of total PSA. The present investigation was designed to evaluate the diagnostic performance of the percent free PSA in the most favorable analytical conditions. Materials and methods 81 patients affected by newly diagnosed, untreated primary prostate cancer (CaP) and 239 patients with untreated benign prostatic hyperplasia (BPH) were prospectively enrolled. Hybritech total and free PSA were measured by the same technician using the same reagent batch. Results The percent free PSA was not significantly associated with age, tumor stage, gland volume, Gleason score, and total PSA, nor was it significantly affected by concomitant prostatic complications either in CaP or BPH. Percent free PSA was more effective than total PSA in the differential diagnosis between CaP and BPH in every evaluated dose range of total PSA. Percent free PSA determination could have reduced the rate of unnecessary biopsies in cases with total PSA ≥ 4 ng/mL and ≥ 10 ng/mL (avoided biopsies 61% and 63%, respectively). The post-test probability of the disease, which represents the proportion of patients with a positive percent free PSA value who have the disease, was, however, relatively low in younger patients with total PSA within the normal range. Conclusions The diagnostic performance of the percent free PSA value is enhanced when the methodological variability is reduced, particularly in men with low total PSA. Percent free PSA is superior to total PSA in distinguishing primary CaP from BPH in patients with total PSA between 2 and 30 ng/mL. The percent free PSA value is effective in reducing the rate of unnecessary biopsies in men with total PSA higher than 4 or 10 ng/mL. However, due to its relatively low post-test probability, the percent free PSA value should be interpreted with caution in the decision-making related to individual patients and should be used in association with clinical and instrumental evaluation of the patient.
Collapse
Affiliation(s)
- R Mione
- Centro Nazionale Applicazione Biotecnologie in Oncologia, Regional Hospital, Venezia, Italy
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
2
|
Chen YT, Tuan LP, Chen HW, Wei IA, Chou MY, Chen HM, Tyan YC, Chen SF. Quantitative Analysis of Prostate Specific Antigen Isoforms Using Immunoprecipitation and Stable Isotope Labeling Mass Spectrometry. Anal Chem 2014; 87:545-53. [DOI: 10.1021/ac5033066] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yi-Ting Chen
- Department
of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan
- Molecular
Medicine Research Center, Chang Gung University, Taoyuan 333, Taiwan
| | - Li-Ping Tuan
- Department
of Chemistry, National Taiwan Normal University, Taipei 11677 Taiwan
| | - Hsiao-Wei Chen
- Molecular
Medicine Research Center, Chang Gung University, Taoyuan 333, Taiwan
| | - I-An Wei
- Department
of Chemistry, National Taiwan Normal University, Taipei 11677 Taiwan
| | - Min-Yuan Chou
- Biomedical
Technology and Devices Research Laboratories, Industrial Technology Research Institute, Chutung 31040, Taiwan
| | - Han-Min Chen
- Department
of Life Science, Catholic Fu-Jen University, Taipei 24205, Taiwan
| | - Yu-Chang Tyan
- Department
of Medical Imaging and Radiological Sciences, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Sung-Fang Chen
- Department
of Chemistry, National Taiwan Normal University, Taipei 11677 Taiwan
| |
Collapse
|
3
|
Peter J, Unverzagt C, Hoesel W. Analysis of Free Prostate-specific Antigen (PSA) after Chemical Release from the Complex with α1-Antichymotrypsin (PSA-ACT). Clin Chem 2000. [DOI: 10.1093/clinchem/46.4.474] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
AbstractBackground: Prostate-specific antigen (PSA), a marker for prostate cancer (CaP), forms a covalent complex with α1-antichymotrypsin (ACT) in human blood. Structural analysis of the PSA-ACT complex is difficult, and complexation may be a reason for biased immunological assays when compared with the analysis of free PSA. We developed a method to cleave the PSA-ACT complex chemically. The liberated PSA was thus available for analysis as free PSA (F-PSA).Methods: PSA was released from the PSA-ACT complex by cleaving the interprotein ester bond with ethanolamine under alkaline conditions. The release was followed by reversed-phase HPLC and an immunoassay for F-PSA. Released PSA obtained from human blood was further immunopurified and analyzed by matrix-assisted laser desorption-induced time of flight (MALDI-TOF) mass spectrometry.Results: In vitro-prepared PSA-ACT complex was completely cleaved by treatment with nucleophilic compounds such as ethanolamine at pH 9–10. The released PSA was stable under these conditions and could be measured by reversed-phase HPLC as well as the ENZYMUN® immunoassay for F-PSA. When plasma from a CaP patient [containing 190 μg/L F-PSA and 1890 μg/L total PSA (T-PSA)] was treated under similar conditions, a concentration of ∼1600 μg/L F-PSA was measured at the end of the incubation, indicating that the PSA-ACT complex was completely cleaved. Two benign prostatic hyperplasia and CaP sera panels (12 and 13 sera, respectively) containing 4–45 μg/L T-PSA were similarly treated. The concentrations of F-PSA measured after incubation were, on average, 85% of the T-PSA values of the untreated sera. Finally, the PSA released from the complex of the CaP plasma was isolated by immunosorption, analyzed by MALDI-TOF mass spectrometry, and compared to PSA obtained from semen. The intact PSA as well as the peptides observed after digestion with endoproteinase Lys C did not reveal any structural difference between the PSA from these two sources.Conclusions: PSA complexed to ACT in plasma of a CaP patient seems to be structurally very similar to the PSA reference material from semen. The release of PSA from the PSA-ACT complex allows F-PSA and T-PSA to be measured by the same immunological assay, thus eliminating any possible bias between two different assays.
Collapse
Affiliation(s)
- Jochen Peter
- Institut für Organische Chemie und Biochemie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
| | - Carlo Unverzagt
- Institut für Organische Chemie und Biochemie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
| | - Wolfgang Hoesel
- Roche Diagnostics GmbH, Nonnenwaldstrasse 2, 82372 Penzberg, Germany
| |
Collapse
|
4
|
Affiliation(s)
- W J Marshall
- Department of Clinical Biochemistry, King's College School of Medicine and Dentistry, London, UK
| |
Collapse
|