| 1. |
- Haese, A., et al.
(author)
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A pre-specified model based on four kallikrein markers in blood improves predictions of adverse pathology and biochemical recurrence after radical prostatectomy
- 2020
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In: British Journal of Cancer. - : Springer Science and Business Media LLC. - 0007-0920 .- 1532-1827. ; 123:4, s. 604-609
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Journal article (peer-reviewed)abstract
- Background A pre-specified model based on four kallikrein markers in blood, commercially available as 4Kscore, predicts Gleason Grade (GG) 3 + 4 or higher prostate cancer on biopsy. However, sampling error and variation in pathology reporting may miss aggressive disease. Methods The 4Kscore was measured in cryopreserved blood from 2330 men obtained before prostatectomy at a single institution between 2002 and 2010. Adverse surgical pathology and biochemical recurrence (BCR) were pre-specified to be assessed in all men, biopsy GG 3 + 3, and 3 + 4. Results Adjusted for established clinical predictors, the 4Kscore was significantly associated with adverse pathology (OR 1.49; 95% CI 1.32, 1.67;p < 0.0001). Adding 4Kscore increased discrimination from (AUC) 0.672 to 0.718 and 0.644 to 0.659 within biopsy GG 3 + 3 and 3 + 4, respectively. Higher 4Kscore was associated with higher risk of BCR (HR 1.16, 95% CI 1.06, 1.26;p = 0.001). Adding 4Kscore improved the prediction of BCR (C-index 0.630-0.660) within GG 3 + 3, but not GG 3 + 4. Conclusions The 4Kscore can help guide the clinical decision whether additional risk assessment-such as confirmatory biopsy-is needed to decide between active surveillance versus curative therapy. Evidence that the panel could influence management in biopsy GG 3 + 4 is less strong and requires further investigation.
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| 2. |
- Phronen, T, et al.
(author)
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Enhanced discrimination of benign from malignant prostatic disease by selective measurements of cleaved forms of urokinase receptor in serum
- 2006
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In: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 52:5, s. 838-844
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Journal article (peer-reviewed)abstract
- Background: Early detection of prostate cancer (PCa) centers on measurements of prostate-specific antigen (PSA), but current testing practices suffer from lack of specificity and generate many unnecessary prostate biopsies. Soluble urokinase plasminogen activator receptor (uPAR) is present in blood in both intact and cleaved forms. Increased uPAR in blood is correlated with poor prognosis in various cancers, but uPAR has not been shown to be useful in PCa diagnostics. We assessed the ability of immunoassays for specific uPAR forms to discriminate PCa from benign conditions. Methods: We measured total PSA (tPSA), free PSA (fPSA), intact uPAR [uPAR(I-III)], intact uPAR + cleaved uPAR domains II+III [uPAR(I-III) + uPAR(II-III)], and cleaved uPAR domain I [uPAR(I)] in sera from 224 men with and 166 men without PCa. We assessed differences in serum concentrations between the PCa and noncancer groups within the entire cohort and in men with tPSA concentrations of 2-10 mu g/L. The diagnostic accuracy of individual analytes and analyte combinations was explored by logistic regression and ROC analyses and evaluations of sensitivity and specificity pairs. Results: Serum uPAR(I) and uPAR(II-III) were higher in PCa than in benign disease. In men with tPSA between 2 and 10 mu g/L, the combination of %fPSA with the ratio uPAR(I)/uPAR(I-III) had a greater area under the ROC curve (0.73) than did %fPSA (0.68). Conclusions: Specific measurements of different uPAR forms in serum improve the specificity of PCa detection. The uPAR forms may therefore be complementary to PSA for PCa detection, most importantly in men with moderately increased PSA. (c) 2006 American Association for Clinical Chemistry.
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| 3. |
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| 4. |
- Haese, A, et al.
(author)
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Isoformen des freien prostataspezifischen Antigens
- 2004
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In: Der Urologe. - : Springer Science and Business Media LLC. - 0340-2592. ; 43:6, s. 675-679
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Journal article (peer-reviewed)abstract
- Detection of prostate-specific antigen remains the mainstay in the early detection of prostate cancer. A problem yet unsolved is the lack of specificity of this organ- but not cancer-specific marker, which generates subsequent, invasive procedures in a high number of patients without detecting prostate cancer. While the separate detection of free PSA and the ratio of free to total PSA has significantly improved specificity while maintaining high sensitivity, the number of patients undergoing unnecessary further diagnostics is still of concern. In this context, the evolving knowledge on isoforms of free PSA is a major focus of current research. Isoforms of free PSA are variants of free PSA that circulate, e.g., as precursor forms, internally cleaved variants of intact molecules, and are suggested to be either more associated with cancer or more with benign diseases. This article describes biochemical and clinical properties of the isoforms of free PSA.
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| 5. |
- Haese, A, et al.
(author)
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Total and Gleason grade 4/5 cancer volumes are major contributors of human kallikrein 2, whereas free prostate specific antigen is largely contributed by benign gland volume in serum from patients with prostate cancer or benign prostatic biopsies
- 2003
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In: Journal of Urology. - : Ovid Technologies (Wolters Kluwer Health). - 1527-3792 .- 0022-5347. ; 170:6, s. 2269-2273
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Journal article (peer-reviewed)abstract
- Purpose: We measured concentrations of human glandular kallikrein 2 (hK2), total prostate specific antigen (tPSA), free PSA (fPSA) and percent fPSA to evaluate their relationship to total prostate gland volume, benign prostatic hyperplasia (BPH) volume, total prostate cancer (PCa) volume (CaVol) and the volume of Gleason grades 4/5 cancer (CaVolG14) in the serum of 256 patients with PCa undergoing radical retropubic prostatectomy and 185 with negative systematic sextant biopsies. Materials and Methods: Free and total PSA was measured using the Delfia Prostatus (Perkin-Elmer, Turku, Finland) total/free PSA assay and hK2 was measured using a research immunofluorometric assay. Transrectal ultrasound was used to determine total prostate and BPH volume. Total CaVol and CaVolG14/5 were calculated using a volumetric program in specimens from 158 men with pT2a/b and 98 with pT3a or greater PCa. The Pearson correlation was performed after logarithmic conversion of PSA and hK2 levels. Benign gland, and pT2a/b and pT3a or greater PCa cases were subdivided into small vs large prostate gland volumes (42 cc or less vs greater than 42 cc). Results: Total prostate and BPH volumes correlated closely with free PSA (r=0.64 to 0.65, p<0.0001) in 143 patients with negative biopsy and a prostate of greater than 42 cc. Correlations of hK2 and tPSA with total prostate and BPH volumes were weaker (r=0.35 to 0.36 and 0.45 to 0.46, respectively). In pT2a/b and pT3a or greater PCa cases hK2 most closely correlated with CaVol (range 0.31 to 0.62, p=0.0072 and <0.0001) and with CaVolG14/5 (range 0.26 to 0.56, p=0.021 and <0.0001, respectively). The tPSA level correlated significantly with CaVol and CaVolG14/5 except in glands 42 cc or greater harboring pT2a/b PCa (p=0.08). Free PSA correlated significantly with CaVolG14/5 only in pT3a or greater PCa (p<0.05), and with CaVol in pT3a or greater PCa and in small prostates harboring pT2a/b PCa. Conclusions: Large benign prostate gland volume affects fPSA more than tPSA in serum. In PCa hK2 more closely correlates with total cancer volume and high grade PCa volume compared with tPSA or fPSA.
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| 6. |
- Steuber, T, et al.
(author)
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Association of free-prostate specific antigen subfractions and human glandular kallikrein 2 with volume of benign and malignant prostatic tissue
- 2005
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In: The Prostate. - : Wiley. - 0270-4137 .- 1097-0045. ; 63:1, s. 13-18
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Journal article (peer-reviewed)abstract
- BACKGROUND. We investigated the association of different subfractions of prostate specific antigen (PSA) and human glandular kallikrein 2 (hK2), such as total PSA (tPSA), complexed PSA (cPSA), free PSA (fPSA), "single-chain Intact fPSA" (fPSA-I), "multi-chain nicked fPSA" (fPSA-N), and total hK2 with volumes of total prostate gland, transition zone (tz), and prostate cancer (PCa) tissue in patients with benign and malignant prostatic disease. METHODS. Serum samples were collected from men with negative biopsy (n = 164) and PCa (n = 252). Total and fPSA were measured using a commercially immunoassay. We measured hK2 and fPSA-I by previously reported in-house research assays specific for hK2 and single-chain, non-cleaved fPSA, respectively. Levels of fPSA-N (=fPSA-fPSA-I) and cPSA (=tPSA-fPSA) were calculated. Total prostate and tz volume were measured using transrectal ultrasound (TRUS); PCa volume was calculated using a computer assisted volumetric program. Association with tz and cancer volumes (CaVols) was performed by linear regression analysis. RESULTS. All PSA subfractions and hK2 were associated with tz volume in multivariable linear regression analysis. Only hK2, fPSA, and fPSA-N were significantly associated with CaVol in multivariable analysis, fPSA-I seemed to be cancer related. CONCLUSIONS. The multi-chain fPSA-N subfractions of fPSA may be a valuable predictor of both benign prostate hyperplasia (BPH) and CaVol that is likely to be more useful in predicting tz volumes than CaVols. fPSA-I may provide information on cancer without being influenced by the presence of BPH.
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| 7. |
- Steuber, Thomas, et al.
(author)
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Comparison of free and total forms of serum human kallikrein 2 and prostate-specific antigen for prediction of locally advanced and recurrent prostate cancer
- 2007
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In: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 53:2, s. 233-240
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Journal article (peer-reviewed)abstract
- Background: We evaluated the association of total and free forms of serum human kallikrein 2 (hK2) and prostate-specific antigen (PSA) with prostate cancers of unfavorable prognosis. Methods: We retrospectively measured total PSA (tPSA), free PSA (fPSA), and total hK2 (thK2) in preoperative serum samples from 867 men [and assessed free hK2 (fhK2) measured in 577 of these men] treated with radical prostatectomy for clinically localized prostate cancer. Associations between biomarker concentrations and extracapsular extension, seminal vesicle invasion, and biochemical recurrence (BCR) were evaluated. A subset of patients with PSA <= 10 mu g/L, the group most commonly seen in clinical practice in the US, was analyzed. Results: thK2 was the strongest predictor of extracapsular extension and seminal vesicle invasion (areas under the ROC curve [AUC], 0.662 and 0.719, respectively), followed by tPSA (AUC, 0.654 and 0.663). All biomarkers were significant predictors of BCR. hK2 forms, but not PSA forms, remained highly significant for predicting BCR in the low-PSA group. Combining tPSA, fPSA, and thK2 in a multivariable model improved prediction compared with any biomarker used individually (AUC, 0.711, 0.755, and 0.752 for this combination predicting extracapsular extension, seminal vesicle invasion, and BCR, respectively; P < 0.001 for all). Conclusions: Increased concentrations of hK2 in the blood are significantly associated with unfavorable features of prostate cancer, and thK2 is predictive of locally advanced and recurrent cancer in patients with PSA <= <= 10 mu g/L. Independent of tPSA and fPSA, hK2 predicts unfavorable prognosis. (c) 2007 American Association for Clinical Chemistry
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| 8. |
- Steuber, T, et al.
(author)
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Discrimination of benign from malignant prostatic disease by selective measurements of single chain, intact free prostate specific antigen
- 2002
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In: Journal of Urology. - 1527-3792. ; 168:5, s. 1917-1922
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Journal article (peer-reviewed)abstract
- Purpose: Free prostate specific antigen (PSA) in serum consists of heterogeneous molecular subforms. Recently we developed an immunoassay for selective measurement of a subfraction of free PSA called intact PSA, which has been shown to be closely associated with prostate cancer. We assessed the ability of serum intact PSA to discriminate between benign and malignant prostatic disease. Materials and Methods: In serum of 178 men with benign disease and 255 men with prostate cancer we measured total PSA and free PSA using a commercially available immunoassay. Intact PSA levels were analyzed by a newly developed assay specific for noncleaved, that is single chain forms of free PSA. Internally cleaved "nicked" PSA was calculated by subtracting intact from free PSA. We also calculated ratios of intact PSA-to-free PSA (intact-to-free PSA) and nicked PSA-to-total PSA (nicked-to-total PSA). We compared means, medians and ranges of all analytes and ratios in patients with and without cancer for the entire total PSA range and in a subset with total PSA ranging from 2 to 10 ng/ml. Furthermore, various combinations of PSA forms were tested for their predictive ability. For statistical comparison we used the Mann-Whitney U test and ROC analysis. Results: The ratio intact-to-free PSA was significantly higher in cancer (median 48.5%) compared to noncancer cases (median 41.8%, p <0.0001). Conversely, the ratio nicked-to-total PSA was significantly higher in men without compared to those with prostate cancer (median 11.0% and 6.0%, respectively, p <0.0001). Highest discriminative ability was observed for a combination of intact, total and free PSA (log [intact, free, total], AUC = 0.773) followed by nicked-to-total PSA (AUC 0.755). In the subgroup of patients with total PSA levels from 2 to 10 ng/ml. only the AUC of log intact, free, total (AUC 0.706, p = 0.0017) and nicked-to-total PSA (AUC 0.704, p = 0.0019) were significantly larger compared to the AUC of total PSA (AUC 0.602). Conclusions: By contrast to measuring crude free PSA concentration, selective determination of specific free PSA subforms, intact PSA and nicked PSA proved to be useful to discriminate men with benign from malignant prostatic disease. These markers may serve to generate specific serum profiles of PSA for improved specificity and early detection of prostate cancer. To translate the encouraging statistical advantage shown in this study into a clinically applicable tool warrants further investigation.
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| 9. |
- Steuber, Thomas, et al.
(author)
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Free PSA isoforms and intact and cleaved forms of urokinase plasminogen activator receptor in serum improve selection of patients for prostate cancer biopsy
- 2007
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In: International Journal of Cancer. - : Wiley. - 0020-7136. ; 120:7, s. 1499-1504
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Journal article (peer-reviewed)abstract
- Clinicians currently use simple cut-points, such as serum prostate-specific antigen (PSA) >= 4 ng/ml, to decide whether to recommend further work-up for prostate cancer (PCa). As an alternative strategy, we evaluated multivariable models giving probabilities of a PCa diagnosis based on PSA and several circulating novel biomarkers. We measured total PSA, free PSA (fPSA), fPSA subfractions (single-chain fPSA-I and multichain fPSA-N), total human glandular kallikrein 2 (hK2) and full-length and cleaved forms of soluble urokinase plasminogen activator receptor (suPAR) in pretreatment serum from 355 men referred for prostate biopsy. Age and total PSA were combined in a "base" regression model to predict biopsy outcome. We then compared this base model to models supplemented by various combinations of circulating markers, using concordance index (AUC) to measure diagnostic discrimination. PCa prediction was significantly enhanced by models supplemented by measurements of suPAR fragments and fPSA isoforms. Addition of these markers improved bootstrap-corrected AUC from 0.611 for a cut-point and 0.706 for the base model to 0.754 for the full model (p = 0.005). This improved diagnostic accuracy was also seen in subanalysis of patients with PSA 2-9.99 ng/ml and normal findings on DRE (0.652 vs. 0.715, p = 0.039). In this setting, hK2 did not add diagnostic information. Measurements of individual forms of suPAR and PSA isoforms contributed significantly to discrimination of men with PCa from those with no evidence of malignancy. (c) 2007 Wiley-Liss, Inc.
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| 10. |
- Steuber, T, et al.
(author)
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Risk assessment for biochemical recurrence prior to radical prostatectomy: significant enhancement contributed by human glandular kallikrein 2 (hk2) and free prostate specific antigen (PSA) in men with moderate PSA-elevation in serum
- 2006
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In: International Journal of Cancer. - : Wiley. - 0020-7136. ; 118:5, s. 1234-1240
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Journal article (peer-reviewed)abstract
- Most models to predict biochemical recurrence (BCR) of prostate cancer use pretreatment serum prostate-specific antigen (PSA), clinical stage and prostate biopsy Gleason grade. We investigated whether human glandular kallikrein 2 (hK2) and free prostate-specific antigen (fPSA) measured in pretreatment serum enhance prediction. We retrospectively measured total PSA (tPSA), fPSA and hK2 in preoperative serum samples from 461 men with localized prostate cancer treated with radical prostatectomy between 1999 and 2001. We developed a regression model to predict BCR using preoperative tPSA, clinical stage and biopsy Gleason grade. We then compared the predictive accuracy of this "base" model with a model with fPSA and hK2 as additional predictors. BCR was observed in 90 patients (20%), including 48 patients with a pretreatment tPSA <= 14 ng/ml (13%), and 28 patients (10%) With a pretreatment tPSA <= 10 ng/ml. Overall, the predictive accuracy of the base model (bootstrap-corrected concordance index of 0.813) was not improved after the addition of fPSA or hK2 (0.818). However, for men with moderate tPSA-elevation (tPSA <= 10 ng/ml), addition of fPSA and hK2 data increased predictive accuracy (from a base model concordance index of 0.756-0.815, p = 0.005). The improvement in accuracy was not sensitive to the threshold for "moderately elevated" PSA. For patients with a moderate tPSA-elevation (tPSA <= 10 ng/ml), which closely corresponds to concurrent disease demographics, BCR-prediction was enhanced when fPSA and hK2 were added to the conventional model. Measurements of fPSA and hK2 improve on our ability to counsel patients prior to treatment as to their risk of BCR. (c) 2005 Wiley-Liss, Inc.
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