| 1. |
- Jacobsen, Steven J., et al.
(author)
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Comparability of the tandem-R andIMx assays for the measurement of serum prostate-specific antigen
- 1994
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In: Urology. - 0090-4295. ; 44:4, s. 512-518
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Journal article (peer-reviewed)abstract
- Objectives.: To assess the comparability of the Tandem-R and IMx serumprostate-specific antigen (PSA) assays across levels of the ratio of free-to-total serum PSA found in a community-based population of healthy men. Methods.: Banked serum samples from the baseline component of the Olmsted CountyStudy of Urinary Symptoms and Health Status Among Men were thawed and analyzed using the Tandem-R and IMx PSA assays. Serum levels also were determined for the free, noncomplexed form of PSA, PSA complexed to alpha-1 antichymotrypsin, and total PSA with a research-based immunofluorometric assay. Results.: The results of the Tandem-R and IMx assays were strongly correlated at alllevels of the ratio of free-to-total serum PSA. The Spearman correlation coefficients ranged from 0.87 to 0.98 (all p < 0.001). The relationship between the Tandem-R and IMx assays, however, differed at low levels of free-to-total serum PSA compared with high levels. In the lowest 10th percentile of the ratio of free-to-total serum PSA (0.04 to 0.18), the IMx assay read lower than the Tandem-R (slope ± standard error = 0.92±0.04, intercept ± standard error = 0.21 ± 0.14); whereas in the upper 10th percentile of free-to-total ratio (0.46 to 0.65) the IMx assay yielded values higher than the Tandem-R assay (slope = 1.21 ± 0.07, intercept = 0.14 ± 0.05). In the middle 90%, the slope did not statistically differ from 1.0. Conclusions.: For the majority of men, results of the Tandem-R and IMx PSA assays were virtually identical. The small differences found would not be of clinical significance for most men but should be considered when comparing results of different assays in sequential determinations for a specific man.
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| 2. |
- Jacobsen, Steven J., et al.
(author)
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Stability of serum prostate-specific antigen determination across laboratory, assay, and storage time
- 1995
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In: Urology. - 0090-4295. ; 45:3, s. 447-453
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Journal article (peer-reviewed)abstract
- Objectives: To understand the comparability of serum prostate-specific antigen (PSA) determinations across assays and storage time. Methods: Serum PSA levels were determined for men aged 40 to 79 years from the clinical subset of the Olmsted County Study of Urinary Symptoms and Health Status Among Men on fresh samples and after a median of 32 months on banked samples, frozen at -70 °C. Baseline serum PSA levels were determined by Tandem-R PSA assay. Follow-up levels on the banked samples were determined by the IMx PSA assay and a repeat Tandem-R PSA assay in a different laboratory and by an immunofluorometric PSA assay at another site. Results: The median serum PSA level determined by Tandem-R assay at baseline was 1.0 ng/mL (25th percentile, 0.6; 75th percentile, 1.7). The distributions of determination made by follow-up Tandem-R, IMx, and immunofluorometric analyses were essentially identical. Overall, the assays were highly correlated. The correlations between the baseline serum PSA determination and repeated Tandem-R, IMx, and immunofluorometric determinations were 0.96, 0.96, and 0.97, respectively (all P < 0.001). The median duration of frozen storage was 32 months (range, 26 to 39 months), and the correlations between baseline and follow-up determinations did not change when stratified by duration of storage. Conclusions: These data provide important reassurance about the use of serum PSA determinations obtained by different assays, in different laboratories, and in properly tored samples across time.
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| 3. |
- Assel, Melissa J., et al.
(author)
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Kallikrein markers performance in pretreatment blood to predict early prostate cancer recurrence and metastasis after radical prostatectomy among very high-risk men
- 2019
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In: Prostate. - : Wiley. - 0270-4137.
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Journal article (peer-reviewed)abstract
- Background: To assess whether a prespecified statistical model based on the four kallikrein markers measured in blood—total, free, and intact prostate-specific antigen (PSA), together with human kallikrein-related peptidase 2 (hK2)—or any individual marker measured in pretreatment serum were associated with biochemical recurrence-free (BCR) or metastasis-free survival after radical prostatectomy (RP) in a subgroup of men with very high-risk disease. Methods: We identified 106 men treated at Mayo Clinic from 2004 to 2008 with pathological Gleason grade group 4 to 5 or seminal vesicle invasion at RP. Univariable and multivariable Cox models were used to test the association between standard predictors (Kattan nomogram and GPSM [Gleason, PSA, seminal vesicle and margin status] score), kallikrein panel, and individual kallikrein markers with the outcomes. Results: BCR and metastasis occurred in 67 and 30 patients, respectively. The median follow-up for patients who did not develop a BCR was 10.3 years (interquartile range = 8.2-11.8). In this high-risk group, neither Kattan risk, GPSM score, or the kallikrein panel model was associated with either outcome. However, after adjusting for Kattan risk and GPSM score, separately, preoperative intact PSA was associated with both outcomes while hK2 was associated with metastasis-free survival. Conclusions: Conventional risk prediction tools were poor discriminators for risk of adverse outcomes after RP (Kattan risk and GPSM risk) in patients with very high-risk disease. Further studies are needed to define the role of individual kallikrein marker forms in the blood to predict adverse prostate cancer outcomes after RP in this high-risk setting.
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| 4. |
- Lonergan, Peter E., et al.
(author)
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Prospective validation of microseminoprotein-β added to the 4Kscore in predicting high-grade prostate cancer in an international multicentre cohort
- 2021
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In: BJU International. - : Wiley. - 1464-4096 .- 1464-410X. ; 128:2, s. 218-224
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Journal article (peer-reviewed)abstract
- Objectives: To prospectively evaluate the performance of a pre-specified statistical model based on four kallikrein markers in blood (total prostate-specific antigen [PSA], free PSA, intact PSA, and human kallikrein-related peptidase 2), commercially available as the 4Kscore, in predicting Gleason Grade Group (GG) ≥2 prostate cancer at biopsy in an international multicentre study at three academic medical centres, and whether microseminoprotein-β (MSP) adds predictive value. Patients and Methods: A total of 984 men were prospectively enrolled at three academic centres. The primary outcome was GG ≥2 on prostate biopsy. Three pre-specified statistical models were used: a base model including PSA, age, digital rectal examination and prior negative biopsy; a model that added free PSA to the base model; and the 4Kscore. Results: A total of 947 men were included in the final analysis and 273 (29%) had GG ≥2 on prostate biopsy. The base model area under the receiver operating characteristic curve of 0.775 increased to 0.802 with the addition of free PSA, and to 0.824 for the 4Kscore. Adding MSP to the 4Kscore model yielded an increase (0.014–0.019) in discrimination. In decision-curve analysis of clinical utility, the 4Kscore showed a benefit starting at a 7.5% threshold. Conclusion: A prospective multicentre evaluation of a pre-specified model based on four kallikrein markers (4Kscore) with the addition of MSP improves the predictive discrimination for GG ≥2 prostate cancer on biopsy and could be used to inform biopsy decision-making.
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| 5. |
- Oesterling, Joseph E., et al.
(author)
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Free, Complexed and Total Serum Prostate Specific Antigen : The Establishment of Appropriate Reference Ranges for their Concentrations and Ratios
- 1995
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In: The Journal of urology. - 0022-5347. ; 154:3, s. 1090-1095
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Journal article (peer-reviewed)abstract
- Purpose: Prostate specific antigen (PSA) exists in the serum in several molecular forms that can be measured by immunodetectable assays: free PSA, PSA complexed to alpha 1-antichymotrypsin (complexed PSA) and total PSA, which represents the sum of the free and complexed forms. We determined the normal distribution of values and established the appropriate reference ranges for these 3 molecular forms of PSA and their ratios (free-to-total, complexed-to-total and free-to-complexed PSA). Knowing the amount and ratio of these molecular forms appears to be useful in enhancing the ability of PSA to distinguish potentially curable prostate cancer from benign prostatic hyperplasia and in decreasing the number of unnecessary prostate biopsies. Materials and Methods: A total of 422 healthy men 40 to 79 years old was randomly chosen from the male population of Olmsted County Minnesota and underwent a detailed clinical examination that included digital rectal examination, serum PSA determination and transrectal ultrasound to exclude the presence of prostate cancer. Using newly developed, monoclonal-monoclonal immunofluorometric assays for each molecular form, the free, complexed and total PSA, and the ratios of these 3 forms were determined for each study participant. Results: All 3 molecular forms correlated directly with patient age (r = 0.45, r = 0.43 and r = 0.45, respectively). Using the 95th percentile, the recommended age-specific reference ranges for the free, complexed and total PSA forms, respectively, are 0.5, 1.0 and 2.0 ng./ml. for men 40 to 49 years old; 0.7, 1.5 and 3.0 ng./ml. for men 50 to 59 years old; 1.0, 2.0 and 4.0 ng./ml. for men 60 to 69 years old, and 1.2, 3.0 and 5.5 ng./ml. for men 70 to 79 years old. With regard to each of the ratios (free-to-total, complexed-to-total and free-to-complexed PSA) none correlated with patient age. As a result, the appropriate upper limit of normal (95th percentile) for all 3 ratios is constant for men of all ages. These reference ranges are greater than 0.15 for free-to-total PSA ratio, less than 0.70 for complexed-to-total PSA ratio and greater than 0.25 for free-to-complexed PSA ratio. The free-to-total PSA ratio will have its greatest value for men with a serum PSA value between 2 and 10 ng./ml. Conclusions: The establishment of appropriate reference ranges for free, complexed and total PSA as well as the ratios will allow the practicing urologist to incorporate these new parameters into the diagnostic evaluation of men at risk for early, potentially curable prostate cancer.
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