Complexed prostate specific antigen (PSA) reduces unnecessary prostate biopsies in the 2.6-4.0 ng/mL range of total PSA

Neutrophil gelatinase-associated lipocalin as a screening test in prostate cancer

OBJECTIVE

Prostate specific antigen (PSA) with digital rectal examination is used for diagnosis of prostate cancer (PCa), where definite diagnosis can only be made by prostate biopsy. Recently neutrophil gelatinase-associated lipocalin (NGAL), a lipocalin family member glycoprotein, come into prominence as a cancer biomarker. This study is aimed to test serum NGAL as a diagnostic biomarker for PCa and discriminate PCa from benign prostatic hyperplasia (BPH).

MATERIAL AND METHODS

In this prospective study, 90 patients who underwent transrectal ultrasound-guided 12-core prostate biopsy between May 2015 and September 2015, were evaluated. Histopathologically diagnosed 45 PCa and 45 BPH patients were enrolled in this study. Serum NGAL and PSA levels of all participants were measured, then these data were evaluated by statistical programs.

RESULTS

When sensitivity fixed to 80% specificity of NGAL was better than PSA (49%, 31% respectively). Receiver operating characteristic (ROC) curve analysis showed that NGAL alone or its combined use with PSA have better area under curve (AUC) results than PSA alone (0.662, 0.693, and 0.623 respectively).

CONCLUSION

In conclusion NGAL gave promising results such as increased sensitivity and a better AUC values in order to distinguish PCa from BPH. NGAL showed a potential to be a non-invasive biomarker which may decrease the number of unnecessary biopsies.

Total, free, and complexed prostate-specific antigen levels among US men, 2007-2010

BACKGROUND

Screening for prostate cancer using prostate-specific antigen (PSA) is common. Prostate cancer has been associated with higher total PSA (tPSA), lower free PSA (fPSA), lower percent free PSA (%fPSA), and higher complexed PSA (cPSA).

METHODS

Total, free and complexed PSAs were performed on 3251 men ≥40years in the 2007-2010 National Health and Nutrition Examination Survey. Distributions of the PSA tests were examined by age, race and ethnicity, and body mass index (BMI) groups. Percentages of men at PSA thresholds were examined.

RESULTS

Total PSA geometric mean was 0.96μg/l among men aged ≥40years and increased from 0.74μg/l for men 40-49years, to 1.82μg/l for men 80years and older. Non-Hispanic Whites had lower age-adjusted mean tPSA (1.03μg/l) and cPSA (0.56μg/l) than non-Hispanic Blacks (tPSA 1.25μg/l and cPSA 0.72μg/l). Obese men had lower age-adjusted mean total, free and complexed PSAs (0.94, 0.27, and 0.51μg/l, respectively) than men with normal BMI (tPSA 1.21, fPSA 0.32, and cPSA 0.68μg/l, respectively).

CONCLUSION

Total, free and complexed PSAs increased with age; tPSA and cPSAs were highest in non-Hispanic Blacks; and total, free, and complexed PSAs were lowest in obese men.

Correlation between the complex PSA/total PSA ratio and the free PSA/total PSA ratio, sensitivity and specificity of both markers for the diagnosis of prostate cancer

OBJECTIVE

To compare the behaviour of the PSAcomplex/PSAtotal percentage (PSAc%) against the PSA free/PSA total (PSAl%) and analyse both markers for their usefulness in diagnosing prostate cancer.

MATERIAL AND METHODS

We measured total PSA (PSAt), free PSA (PSAl), complex PSA (PSAc), PSAl% and PSAc% levels in 158 patients. Of these, 98 (62%) were biopsied for presenting PSAt≥3 ng/dl and PSAl%<20, PSAt>10, suspicious rectal examination or suspicious ultrasound node. We performed linear regression and Passing-Bablok regression analyses. The ROC curves were calculated to study the sensitivity and specificity of PSAl% and PSAc% and were compared to each other. The prostate cancer diagnoses were analysed by PSAl% and PSAc% by applying the χ(2) test.

RESULTS

The correlation coefficient (r) was good (0.7447, P<.0001), and the index of determination (r(2)) was 0,5. The result of the Passing-Bablok analysis was a slope of 1.658 (1.452 to 1.897) and an intersection of 2.044 (-0,936 to 5.393). The optimal cutoff for PSAl% (≤14.7854) showed a sensitivity of 89.29% [95% CI, 0,642-0,823] and a specificity of 54.29% (95% CI, 0,642-0,823). The optimal cutoff for PSAc% (>89.7796) had a sensitivity of 71.43% (95% CI, 0,616-0,802) and a specificity of 71.43% (95% CI, 0,616-0,802). There were no significant differences when comparing the areas under the curve of both markers (P=.59). The PPV of PSAl% was less than that of PSAc% (45.7% vs. 71%).

CONCLUSION

There was a good correlation between PSAl% and PSAc%. PSAc% has demonstrated greater specificity and efficacy than PSAl% in the diagnosis of prostate cancer.

Free prostate-specific antigen provides more precise data on benign prostate volume than total prostate-specific antigen in korean population

Purpose

To investigate the efficacy of total prostate-specific antigen (tPSA) and free prostate-specific antigen (fPSA) for the estimation of prostate volume (PV) in pathologically-proven benign prostatic hyperplasia (BPH) patients.

Methods

From January 2010 to March 2013, 165 Korean men with a PSA less than 10 ng/mL who were diagnosed without prostate cancer by prostate biopsy were enrolled. Patients were classified into three age groups: ≤60, 61-70, and >70 years old. The results were organized to estimate and compare the ability of serum tPSA and fPSA to assess the PV.

Results

Enrolled patients had a median age of 63.5 years (44 to 80), a median tPSA of 5.72 ng/mL, a median fPSA of 0.98 ng/mL and a median PV of 53.68 mL, respectively. Among the associations between tPSA, fPSA, age, and PV, the highest correlation was verified between fPSA and PV (r=0.377, P<0.0001); the correlation coefficient between tPSA and PV was much lower (r=0.262, P<0.001). All stratified age cohorts showed the same findings. The ROC curves (for PV greater than 30, 40, and 50 mL) showed that fPSA (area under the curve [AUC]=0.781, 0.718, and 0.700) outperformed tPSA (AUC=0.657, 0.583, and 0.67) in its ability to predict clinically significant PV enlargement.

Conclusion

Both tPSA and fPSA significantly correlated with PV in Korean men, while the correlation efficiency between fPSA and PV was more powerful. fPSA may be a useful tool in making therapeutic decisions and follow-up management in BPH patients.

Detection of prostate cancer with complexed PSA and complexed/total PSA ratio - is there any advantage?

OBJECTIVE

To evaluate the performance of total PSA (tPSA), the free/total PSA ratio (f/tPSA), complexed PSA (cPSA) and the complexed/total PSA ratio (c/tPSA) in prostate cancer detection.

METHODS

Frozen sera of 442 patients have been analysed for tPSA, free PSA (fPSA) and cPSA. 131 patients had prostate cancer and 311 patients benign prostatic hyperplasia.

RESULTS

Differences in the distribution of the biomarkers were seen as follows: tPSA, cPSA and c/tPSA were significantly higher in the PC group, and f/tPSA was significantly higher in the BPH group. In the tPSA-range of 0-4 ng/ml none of the biomarkers showed a significant difference in the distribution between both groups. In the tPSA-ranges of 0-10 ng/ml, 2-10 ng/ml, 4-10 ng/ml and <10 ng/ml, f/tPSA showed the highest specificity at high sensitivtities, followed by c/tPSA, cPSA, and tPSA, respectively. In tPSA-ranges greater than 10 ng/ml, cPSA offered the best discriminatory ability. CPSA compared to tPSA offered better specificity at high sensitivities in all tPSA-ranges.

CONCLUSION

F/tPSA offers the best ability to distinguish between both groups in lower tPSA-ranges, followed by c/tPSA. CPSA compared to tPSA offers a better ability to discriminate between both groups in all PSA-ranges and could be used as an initial test for PC.

Development of simultaneous detection of total prostate-specific antigen (tPSA) and free PSA with rapid bead-based immunoassay

OBJECTIVE

Prostate-specific antigen (PSA) is the most important biochemical tumor marker for the early detection of prostate cancer; however, its diagnostic specificity is low. Therefore, free PSA (fPSA) test is recommended as an adjunct to increase the specificity. However, all the current technology only allows detecting one biomarker at one time. In this study, we reported a flexible bead-based immunoassay to measure total PSA (tPSA) and fPSA simultaneously.

MATERIALS AND METHODS

We used the Luminex xMAP bead array technology to measure tPSA and fPSA at one time, employing two mouse monoclonal anti-PSA antibodies (5G6 and 8A6) for coating and another mouse monoclonal anti-PSA antibody (5A6) for detection. Then we compared the data of Luminex assay with that of the conventional enzyme-linked immunosorbent assay (ELISA).

RESULTS

The assay was fast with a wide dynamic range. The lower detection limit for tPSA and fPSA were 2.3 and 1.3  pg/ml. The inter-assay coefficients for tPSA and fPSA were between 5.64 and 7.65%, and the intra-assay coefficients for tPSA and fPSA were between 4.15 and 5.89%. A close correlation between the new assay and the conventional ELISA was observed.

CONCLUSIONS

The bead-based platform is rapid, sensitive, and less expensive, which allows both single sample and high-throughput measurement of tPSA and fPSA over a wide range of concentrations.

[PSA and hK2 in the diagnosis of prostate cancer]

Serum markers for prostate carcinoma are widely applied for the purpose of early detection of cancer and the differentiation between benign and malignant disease, for the pre-treatment staging of detected prostatic cancers, and for the monitoring of prostate cancer after curative or palliative therapies. Since its discovery in 1979, serum PSA has been the most powerful marker of prostate cancer, but, when used alone, PSA is not sufficiently sensitive or specific to consider it an ideal tool for the early detection or staging of prostate cancer. To optimize the use of PSA, the concepts of PSA velocity, PSA density, and age-related PSA values were developed. Moreover, the molecular forms of PSA, especially the percentage of free PSA, seem to be useful tools for the detection of prostate cancer in men with slightly elevated total PSA. Human kallikrein 2 (hK2), a serine protease closely related to PSA that also is expressed predominantly in the prostate, is a new complementary marker to PSA for early detection of prostate cancer. In this review, we examine PSA testing and its effectiveness in the diagnosis of prostate cancer. Further, we also evaluate recent literature regarding the use of hk2.

Comparison of the clinical value of complexed PSA and total PSA in the discrimination between benign prostatic hyperplasia and prostate cancer

BACKGROUND

To compare the clinical value of the measurement of complex and total PSA in the discrimination between benign prostatic hyperplasia (BPH) and prostate cancer.

METHODS

In serum samples collected from 166 men with histopathologically proven clinically localized prostate cancer and of 97 men with BPH, total prostate-specific antigen (PSA), complexed PSA and the free to total PSA ratio were determined. The statistical analysis was done by the comparison of the receiver operator characteristic (ROC) curves.

RESULTS

The areas under the ROC curves were 0.776 for total PSA, 0.799 for complexed PSA (total PSA vs. cPSA: p < 0.0001) and 0.812 for the free to total PSA ratio. With a cut-off of 3.0 ng/ml for complexed PSA, the sensitivity was 90%, the specificity 58%, the positive and the negative predictive values 79 and 78%, respectively. With a cut-off of 4.0 ng/ml for total PSA, the sensitivity was 87%, the specificity 59%, the positive and the negative predictive values were 78 and 72%, respectively.

CONCLUSIONS

There was a statistically significant advantage for complexed PSA compared to total PSA in the discrimination between BPH and prostate cancer. The difference was, however, small and its clinical relevance is questionable.

Interchangeability of measurements of total and free prostate-specific antigen in serum with 5 frequently used assay combinations: an update

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.

METHODS

Sera from 314 patients with prostate cancer (PCa) and 282 men with no evidence of prostate cancer (NPCa) were measured with tPSA and fPSA assays from Abbott (AxSYM), Beckman Coulter (Access), Diagnostic Products Corporation (Immulite 2000), and Roche (Elecsys 2010) and with tPSA and complexed PSA (cPSA) assays from Bayer (ADVIA Centaur).

RESULTS

Method comparisons (Passing and Bablok regressions; Bland-Altman plots) showed assay-dependent results for tPSA, fPSA, and %fPSA. With the Access tPSA values taken as 100%, tPSA concentrations varied from 87% (AxSYM and ADVIA Centaur) to 115% (Immulite), leading to different numbers of patients classified according to the commonly recommended tPSA cutoffs for performing a biopsy. Different %fPSA values also led to assay-dependent ROC analysis results, a finding that shows the importance for the diagnostic accuracy.

CONCLUSION

Interchangeability of tPSA, fPSA, and %fPSA values obtained by commercial PSA assays remains inadequate, but attention to this issue may minimize the misinterpretation of PSA results obtained by different assays.

The Detection and Potential Economic Value of Complexed Prostate Specific Antigen as a First Line Test

PURPOSE

Prostate cancer detection is subject to a number of variables that can lead to unnecessary biopsies and associated costs. Measuring cPSA has been proposed as an alternative to tPSA for the early detection of prostate cancer.

MATERIALS AND METHODS

Between November 1998 and April 2000, 1,362 men underwent transrectal ultrasound guided biopsies at 7 institutions. Of 1,243 evaluable men 467 with tPSA between 2.5 and 6.0 ng/ml, and normal digital rectal examination were analyzed. Statistical analysis used to compare cancer detection rates between PSA assays was performed using the Mann-Whitney U test. A separate group of 2,807 men who participated in a free cancer detection program was used to determine the current tPSA distribution and assess the economic impact of cPSA.

RESULTS

Cancer was detected in 31.5% of the men (147 of 467) with tPSA between 2.5 and 6.0 ng/ml. Using a 2.2 ng/ml cPSA cutoff point detected 93.9% of cancers and would have avoided 20.3% of unnecessary biopsies in men with tPSA between 2.5 and 4.0 ng/ml. A 2.2 ng/ml cPSA cutoff point achieved an 11.9% overall decrease in the number of unnecessary biopsies in the tPSA range of 2.5 to 6.0 ng/ml with accompanying 98% sensitivity. The decrease in unnecessary biopsies is potentially associated with substantial health care cost savings.

CONCLUSIONS

In the clinically relevant sensitivity ranges a 2.2 ng/ml cPSA cutoff point decreases the number of unnecessary biopsies and maintains higher specificity than a tPSA threshold of 2.5 ng/ml, illustrating the potential value of cPSA as a first line diagnostic test.

Complexed PSA improves prostate cancer detection: Results from a multicenter Japanese clinical trial

OBJECTIVES

To compare the distribution of total and complexed prostate-specific antigen (cPSA) in men with and without prostate cancer with another studied population and to ascertain whether cPSA could enhance the detection of prostate cancer in Japanese men.

METHODS

A total of 760 men whose serum total PSA (tPSA) values ranged from 1.0 to 100 ng/mL were enrolled. Serum samples for tPSA and cPSA (ADVIA Centaur) were obtained in all cases. The area under the curve was calculated for comparison of the tPSA and cPSA values. We calculated the number of cancers missed and false-positive results at various cutoff values of cPSA compared with the conventional tPSA threshold of 4.0 ng/mL.

RESULTS

Prostate cancer was detected in 268 (35.3%) of 760 patients. cPSA was greater than 8.3 ng/mL (equivalent to 10.0 ng/mL tPSA) in 46.6% of the men with cancer. The area under the curve for cPSA (0.741) was significantly better than that for tPSA (0.721, P <0.001). At a sensitivity of 85% to 95%, significant differences were found in the corresponding specificity between tPSA and cPSA. cPSA at a 3.0-ng/mL threshold detected an identical number of cancers as a tPSA cutoff of 4.0 ng/mL; however, it decreased the false-positive results by 28 cases.

CONCLUSIONS

To our knowledge, this is the first report of the distribution of cPSA in Japanese men using a urologic referral population. cPSA can be an alternative to tPSA as the first screening test. A substantial number of men in Japan with prostate cancer are currently diagnosed with a tPSA value greater than 10.0 ng/mL.

Use of prostate-specific antigen (PSA) isoforms for the detection of prostate cancer in men with a PSA level of 2-10 ng/ml: systematic review and meta-analysis

OBJECTIVE

Measurement of serum prostate-specific antigen (PSA) for the detection of prostate cancer has poor specificity in men with PSA levels between 2 and 10 ng/ml. It has been suggested that measurement of the ratio of free to total PSA (f/tPSA) or complexed PSA (cPSA) might offer an improvement. We performed a systematic review and meta-analysis to evaluate the diagnostic performance of these tests among men with PSA levels between 2 and 10 ng/ml.

METHODS

Data on sensitivity and specificity were extracted from 66 eligible studies. Likelihood ratios and summary receiver operating characteristic curves were estimated and possible sources of heterogeneity between studies examined.

RESULTS

Use of the f/tPSA or the cPSA test improved diagnostic performance among men with a total PSA (tPSA) of 2-4 or 4-10 ng/ml compared to tPSA alone. The diagnostic performance of the f/tPSA test was significantly higher in the tPSA range of 4-10 ng/ml compared to a tPSA range of 2-4 ng/ml (p < 0.01); at a sensitivity of 95%, the specificity was 18% in the 4-10 ng/ml tPSA range and 6% in the 2-4 ng/ml tPSA range. Among studies that measured both isoforms, the diagnostic performance of the f/tPSA test and the cPSA was equivalent in both PSA ranges.

CONCLUSIONS

The use of the f/tPSA or cPSA test among men with PSA levels between 2 and 10 ng/ml can reduce the number of unnecessary biopsies whilst maintaining a high cancer detection rate.

Prostatitis and serum prostate-specific antigen

Prostatitis is an inflammatory condition of the prostate and has been divided into four categories according to the National Institutes of Health classification. This article reviews the various types of prostatitis and their effect on serum prostate-specific antigen levels. Various proposed mechanisms of this elevation include leakage of prostate-specific antigen (PSA) into the blood stream, hypervascularity, and altered vascular permeability secondary to inflammation. Acute prostatitis can lead to an increase in PSA, which usually returns to normal levels with appropriate antibiotics within 1 to 3 months. Patients with chronic prostatitis have a less well-defined decrease in PSA after an antibiotic course. Whether a course of antibiotics prior to biopsy increases the yield has not been well established. Asymptomatic inflammation of the prostate has been recognized to be an important confounding factor in patients with an elevated PSA. Inflammation has been proposed to be a precursor of prostate adenocarcinoma.

Survival of patients with prostate cancer and normal PSA levels treated by radical prostatectomy

INTRODUCTION

The unpredictability of prostate cancer has become a daily challenge for the urologist, with different strategies being required to manage these cases. In this study, we report on the perspectives for curing prostate cancer in males undergoing radical prostatectomy with Gleason score of 2-6 on prostate biopsy in relation to pre-operative PSA levels.

MATERIALS AND METHODS

From 1991-- 2000, we selected 440 individuals whose pathological diagnosis revealed a Gleason score of 2-6 upon prostate biopsy and who subsequently underwent retro-pubic radical prostatectomy due to localized prostate cancer. The clinical stage identified in the group under study was T1c: 206 (46.8%); T2a: 122 (27.7%); T2b: 93 (21.1%); T2c: 17 (3.9%); T3a: 2 (0.5%). Following surgery, we constructed a biochemical recurrence-free survival curve according to pre-operative PSA levels between 0-4; 4.1-10; 10.1-20 and > 20 ng/mL, with a median follow-up of 5 years.

RESULTS

Following radical prostatectomy, the pathological stage was confirmed as pT2a: 137 (31.1%); T2b: 118 (26.8%); T2c: 85 (19.3%); T3a: 67 (15.2%); T3b: 6 (1.4%); T3c: 22 (5%). The biochemical recurrence-free survival, according to PSA values between 0-4; 4.1-10; 10.1-20 and > 20 ng/mL, was 86.6%, 62.7%, 39.8% and 24.8% respectively.

CONCLUSION

Better chances for curing low-grade prostate cancer occur in individuals with normal PSA for whom a biopsy is not usually recommended.

Innovations in serum and urine markers in prostate cancer current European research in the P-Mark project

An overview is given of serum and urine prostate cancer markers that are currently under investigation and subsequently the P-Mark project is introduced. There are many markers showing promise to overcome the limitations of prostate specific antigen (PSA). Eventually, these markers should be able to increase the specificity in diagnosis, differentiate between harmless and aggressive disease and identify progression towards androgen independence at an early stage. In the P-Mark project, several recently developed, promising markers will be evaluated using clinically well-defined biorepositories. Following successful evaluation, these markers will be validated on a sample set derived from two large, European, prostate cancer studies and used for the identification of special risk groups in the general population. In addition, novel markers will be identified in the same biorepositories by different mass spectrometry techniques.

Complexed prostate specific antigen density is better than the other PSA derivatives for detection of prostate cancer in men with total PSA between 2.5 and 20 ng/ml: results of a prospective multicenter study

PURPOSE

This prospective, multicenter study was initiated to evaluate the diagnostic performance of PSA, free/total PSA (f/tPSA) and complexed PSA (cPSA) with volume-based parameters for early detection of prostate cancer in patients with PSA between 2.5 and 20 ng/ml.

MATERIALS AND METHODS

408 subjects with serum PSA values between 2.5 and 20 ng/ml regardless of digital rectal examination (DRE) were included in to the study. The diagnostic validity, sensitivity, specificity and cut-off values were evaluated by Receiver Operating Characteristic (ROC) curve analysis.

RESULTS

Of 408 patients 77 (18.9%) were positive for prostate cancer. Digital rectal examination was non-suspicious in 86% (351/408) of the patients. Area under curve (AUC) values for cPSA were better than PSA and f/tPSA in patients with PSA values of 2.5-10 ng/ml and 4-10 ng/ml, as well as the whole group. Furthermore, on ROC curve analysis cPSAD was the best predictor of prostate cancer for all PSA ranges regardless of the DRE findings except PSA values between 2.5 and 4 ng/ml. The cut-off value of cPSAD at 90% sensitivity was 0.06 ng/ml/cm(3) with a 35.3% specificity saving 126 unnecessary biopsies in the whole group.

CONCLUSION

cPSA might be a better initial test than PSA for prostate cancer detection and measurement of cPSA alone and its derivatives obviate the need for additional fPSA testing.