Impact of free prostate-specific antigen on discordant measurement results of assays for total prostate-specific antigen

Semjonow, Axel; Oberpenning, F.; Brandt, Burkhard; Zechel, Christian; Brandau, Wolfgang; Hertle, L.

doi:10.1016/s0090-4295(96)00604-8

Cited by 45 publications

(23 citation statements)

References 16 publications

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“…2, C and D). These differences were not shown in previous studies with fewer serum samples (21 ) or with experiments using the WHO reference materials (13 ). For samples with %fPSA values Ͻ25%, the responses obtained with the Immulite and Elecsys tPSA assays were equimolar, as demonstrated by the slopes of the regression lines, which did not differ significantly from zero (P ϭ 0.105 and 0.099 for Immulite and Elecsys).…”

Section: Resultsmentioning

confidence: 54%

Interchangeability of Measurements of Total and Free Prostate-Specific Antigen in Serum with 5 Frequently Used Assay Combinations: An Update

et al. 2006

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Background:The comparability of total and free prostate-specific antigen (tPSA and fPSA) results among commercial PSA assays has been suggested to be improved by calibration to WHO PSA reference materials and the development of equimolar-response assays. To characterize the current situation, we assessed 5 frequently used commercial assay combinations for tPSA and fPSA regarding the interchangeability of the PSA values and the ratio of fPSA to tPSA (%fPSA), equimolar characteristics, and diagnostic accuracy.

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Section: Resultsmentioning

confidence: 54%

Interchangeability of Measurements of Total and Free Prostate-Specific Antigen in Serum with 5 Frequently Used Assay Combinations: An Update

et al. 2006

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“…Responding to Graves' (1) and subsequently Sokoloff´s (2) early recommendations, assay producers have withdrawn PSA assays from the market that did not exhibit equimolarresponse assay characteristics. As was expected (3,13), assay suppliers who developed assays for free PSA, but whose total PSA assays were not equimolarresponse assays, made efforts to modify their total PSA assays. Consequently, nonequimolar-response assays have already been superseded or withdrawn (14) and it can be anticipated that more assay modifications will appear on the market (10).…”

Section: Discussionmentioning

confidence: 94%

A New Modification of the Chiron ACS Assay for Total Prostate-Specific Antigen Achieves Equimolar Response Characteristics and Improves the Detection of Prostate Cancer

Oberpenning¹,

Weining²,

Brandt³

et al. 2003

Clinical Chemistry and Laboratory Medicine

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Nonequimolar-response assays for prostate-specific antigen (PSA) are criticized for overestimating total PSA in some men without prostate cancer (PCA), and underestimating total PSA in some men with PCA. We recently studied three nonequimolar-response PSA assays that had undergone modifications. While two of the studied assays achieved equimolar-response characteristics with improved areas under receiver operating characteristic (ROC) curves (AUC), the modification of the Chiron ACS PSA assay (ACS PSA2, Chiron) failed to achieve this. Recently, the ACS assay underwent another modification (ACS PSA, Bayer), which we investigated.Sera from 305 men (155 without and 150 with PCA, PSA ≥ 2 and ≤ 30 µg/l, Tandem-E) were measured using both modifications of the ACS assay and equimolar-response reference methods (Tandem-R free and Tan

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“…A lower relative proportion is associated with higher probability of prostate cancer [11]. Published guidelines for the clinical use of %fPSA have been contradictory because of differences in assay systems, study designs, patient populations, and the number of subjects enrolled [12,13]. A large well-controlled multicenter clinical trial was conducted to define a clinical significant %fPSA cutpoint that would indicate the need for prostate biopsy with a high rate of cancer detection (clinical sensitivity) while avoiding negative biopsies in men without cancer (clinical specificity) when total PSA (tPSA) is between 4.0 and 10.0 ng/ml.…”

Section: Introductionmentioning

confidence: 99%

Clinical Usefulness of Free PSA in Early Detection of Prostate Cancer

et al. 2001

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Objective: Measurement of serum prostate-specific antigen (PSA) is widely used as an aid in early detection of prostate cancer. Most patients with prostate cancer and a PSA level less than 10.0 ng/ml have early-stage disease. Thus, the detection of prostate cancer in its potentially curable stages requires the use of low PSA cutoffs, inevitably leading to many unnecessary biopsies. The combined use of free PSA and total PSA increases specificity of early detection. To develop risk assessment guidelines and a cutoff value of ratio of free (f) to total (t) PSA with a high predictive value for prostate cancer in men to whom the test would be applied in real life practice, a multicenter early detection trial was initiated. Patients and Methods: In one week in November 1997, 963 urologists prospectively examined 11,644 men between 45 and 75 years by digital rectal examination (DRE) and prostate-specific antigen with 4.0 ng/ml as cutoff. Data of physical examination were collected by questionnaire. At this time participants were not aware of their PSA values. Suspicious findings were further investigated with sextant biopsy. Prostate volume was determined with transrectal ultrasound (TRUS). Different cutoff levels were correlated to age and detection rate. Results: From1,115 biopsied men, the data of 633 men fulfilled the criteria DRE-negative, TRUS-estimated volume, and PSA 4.0–10.0 ng/ml. In that cohort 91 cancers were detected. Percentage of fPSA was significantly more predictive of cancer than tPSA (p < 0.001). The area under the ROC curve was 0.72 for percent fPSA (% fPSA) and 0.62 for total PSA. The cancer risk nearly doubled using a cutoff of 10% fPSA, the median %PSA level of the detected cancers. A better discrimination of cancer and noncancer especially in the age group above 70 years is possible. Using a cutoff of 16% fPSA increases positive predictive value (PPV) to 25% missing only 4% of cancers. Nearly 45% of the biopsies could be avoided. In the age group 45–69 years, a cutoff of 20% fPSA leads to PPV of 15%, missing 6% of cancers. Unnecessary biopsies could be avoided in 12%. Conclusions: Using % fPSA in early detection of prostate cancer reduces the number of unnecessary biopsies, especially in men with negative rectal examination in the PSA range of 4.0–10.0 ng/ml. In order to diminish biopsy rate in men 70 years or older a cutoff of 16% fPSA should be used. A cutoff of 20% fPSA in men younger than 70 years is recommended to increase sensitivity in that age group.

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Impact of free prostate-specific antigen on discordant measurement results of assays for total prostate-specific antigen

Cited by 45 publications

References 16 publications

Interchangeability of Measurements of Total and Free Prostate-Specific Antigen in Serum with 5 Frequently Used Assay Combinations: An Update

Interchangeability of Measurements of Total and Free Prostate-Specific Antigen in Serum with 5 Frequently Used Assay Combinations: An Update

A New Modification of the Chiron ACS Assay for Total Prostate-Specific Antigen Achieves Equimolar Response Characteristics and Improves the Detection of Prostate Cancer

Clinical Usefulness of Free PSA in Early Detection of Prostate Cancer

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