Multicenter Evaluation of the Performance and Clinical Utility in Longitudinal Monitoring of the Bayer Immuno 1™ Complexed PSA Assay

Prostate-Specific Antigen as an Ultrasensitive Biomarker for Patients with Early Recurrent Prostate Cancer: How Low Shall We Go? A Systematic Review

Serum prostate-specific antigen (PSA) needs to be monitored with ultrasensitive PSA assays (uPSAs) for oncologists to be able to start salvage radiotherapy (SRT) while PSA is <0.5 µg/L for patients with prostate cancer (PCa) relapsing after a radical prostatectomy (RP). Our systematic review (SR) aimed to summarize uPSAs for patients with localized PCa. The SR was registered as InPLASY2023110084. We searched for studies on Google Scholar, PUBMED and reference lists of reviews and studies. We only included studies on uPSAs published in English and excluded studies of women, animals, sarcoidosis and reviews. Of the 115 included studies, 39 reported PSA assay methods and 76 reported clinical findings. Of 67,479 patients, 14,965 developed PSA recurrence (PSAR) and 2663 died. Extremely low PSA nadir and early developments of PSA separated PSAR-prone from non-PSAR-prone patients (cumulative p value 3.7 × 1012). RP patients with the lowest post-surgery PSA nadir and patients who had the lowest PSA at SRT had the fewest deaths. In conclusion, PSA for patients with localized PCa in the pre-PSAR phase of PCa is strongly associated with later PSAR and survival. A rising but still exceedingly low PSA at SRT predicts a good 5-year overall survival.

Effect of ejaculation on Serum Prostate-Specific Antigen concentration

Abstract

Purpose:To evaluate the effect of ejaculation on serum prostate-specific antigen (PSA) concentrations in patients with lower urinary tract symptom (LUTS).

Materials and Methods

Our study includes 98 men (62 study and 36 control). After three days of sexual abstinence, blood samples were drawn for the measurement of baseline PSA levels. Then the patients were told to ejaculate. One, 5, 24 and 72 hours after ejaculation, serum total (tPSA), free (fPSA) and complexed PSA (cPSA) levels were measured. Serum PSA sampling was performed at the same intervals in the control group without ejaculation.

Results

The mean age in study and control groups patients were 59.03±0.99 years, 61.14±1.30 years, respectively. In the study group, changes in tPSA and fPSA levels after ejaculation were found statistically significant while changes in cPSA levels and f/tPSA ratios were not significant (p=0.016, p=0.0003, p=0.176, and p=0.173, respectively). Baseline values showed significant differences with 1st and 5th hours. No significant changes in tPSA, fPSA, cPSA levels and f/tPSA values were found in control group (p=0.223, p=0.224, p=0.444, and p=0.718, respectively). The changes in the number of patients exceeding the cutoff values after ejaculation were not statistically significant for tPSA, cPSA, and f/tPSA ratio.

Conclusions

In this study, ejaculation increased tPSA and fPSA concentrations but it didn’t have a significant effect on serum cPSA levels and f/tPSA ratios. However, recent ejaculation may affect the biopsy indication at least near cut off PSA values. Further studies are needed to explain the mechanisms of alterations in the concentration of PSA.

A Review on the Clinical Utility of PSA in Cancer Prostate

Prostate cancer has come to share the oncological centrestage among male cancers. The availability of Serum Prostate Specific Antigen, PSA, as a marker has encouraged it's use to diagnose both cancer and cancer recurrence. Some clarity is required about its precise role in clinical practice. The available literature on Prostate Specific Antigen was reviewed; Articles were reviewed for content, applicability to the problem at hand, availability of data about sensitivity and specificity of values, refinements in measurements and finally for impact of screening programmes using these values on survival and quality of life. The data in the literature was critically re-evaluated and analysed to draw reasonable conclusions. Serum PSA measurements show variable reliability when it comes to diagnosis of Prostate cancer, given the dynamics of PSA physiology. Surrogate measures like PSA density, PSA velocity, free-to-complexed PSA ratio, percentage Pro-PSA, etc., have been used to improve the predictive utility of this assay for Prostate cancer. The ability of PSA to detect those cancers that will cost life, and thereby permit early curative treatment, is as yet unclear. It's most definitive role appears to be in diagnosing recurrences after adequate surgical treatment, and in evaluating response to treatment.

Complexed prostate-specific antigen for the diagnosis of biochemical recurrence after radical prostatectomy

OBJECTIVES

To determine the validity of using complexed prostate-specific antigen (cPSA) levels for diagnosing biochemical recurrence after radical prostatectomy (RP).

PATIENTS AND METHODS

With linear regression modelling, we determined threshold cPSA levels for biochemical recurrence in patients after RP for clinically localized prostate cancer. We calculated sensitivity, specificity, predictive values, and likelihood ratio tests of each threshold for diagnosing biochemical recurrence using total PSA (tPSA) as the reference standard.

RESULTS

In the regression models, tPSA and cPSA were highly correlated (r = 0.99). For the diagnosis of biochemical recurrence, tPSA thresholds of 0.20 and 0.40 ng/mL corresponded to cPSA thresholds of 0.12 ng/mL (95% confidence interval 0.08-0.17) and 0.29 (0.22-0.28) ng/mL, respectively. For the detection of biochemical recurrence, a cPSA threshold of 0.12 ng/mL had a sensitivity of 96%, specificity of 88%, positive predictive value of 89%, negative predictive value of 88%, positive likelihood ratio of 8, and negative likelihood ratio of 0.05; the respective values for a cPSA threshold of 0.29 ng/mL were 96%, 96%, 96%, 96%, 24 and 0.04.

CONCLUSIONS

cPSA has high validity for the diagnosis of biochemical recurrence after RP. Pending external validation, cPSA might be useful for biochemical surveillance after RP.

Les formes moléculaires du PSA

Molecular forms of serum PSA (prostate specific antigen) have been developped to improve total PSA sensitivity and specificity in prostate cancer diagnosis and staging. Total PSA is measured in bound (complexed PSA) and unbound (free PSA) molecular forms. Their levels in absolute values and in relation to total PSA (f/t PSA and c/t PSA) have been evaluated. The percentage of free PSA is more specific but less sensitive than tPSA and it is not recommended as a first line diagnostic test. It may be useful as a second-line test, prescribed by the urologist after a first series of negative biopsies. There is general agreement that at high sensitivity, cPSA provides higher specificity compared with tPSA in the gray zone (2-10 ng/ml). Nevertheless the widespread use of tPSA an the small benefit in terms of specificity explains why cPSA is not generally recommanded. Molecular derivates of free PSA have been identified: proPSA (precursor inactive form of PSA), intact PSA (an additionnal form of proPSA that is found intact and inactive), human Kallikrein 2 and BPSA (for benign PSA wich is associated to BPH) have been evaluated. Preliminary studies did not have demonstrate their ability to discriminate between cancer and BPH, and did not define cutoff values.

Effect of hemodialysis on serum complexed prostate-specific antigen levels

OBJECTIVE

The measurement of prostate-specific antigen (PSA) is a useful tool in the screening and follow-up of prostate cancer, but its diagnostic validity is uncertain in hemodialysis patients. The aim of this study was to evaluate the effects of hemodialysis on serum complexed PSA (cPSA) levels.

MATERIAL AND METHODS

A total of 36 men (mean age 62.54+/-8.20 years) with end-stage renal disease were enrolled in a prospective study. Serum total PSA (tPSA), free PSA (fPSA) and cPSA, and hematocrit levels were measured before and immediately after dialysis using low-flux membranes in the serum and in the dialysis ultrafiltrate.

RESULTS

After hemodialysis, cPSA, fPSA and the fPSA:tPSA ratio increased significantly (p<0.05). However, there was no significant increase in tPSA. fPSA, cPSA and tPSA were not detected in ultrafiltrate. Hematocrit levels increased significantly (p<0.0001) due to hemoconcentration. Of patients with initial serum tPSA and cPSA values and fPSA:tPSA ratios below the cut-off values, none had a post-hemodialysis value greater than the cut-off point. There were weak correlation between the difference in values after and before hemodialysis of hematocrit and cPSA (p=0.035), and between the percentage change in levels before and after hemodialysis of hematocrit and cPSA (p=0.041).

CONCLUSIONS

Hemodialysis induced elevations in all forms of PSA, but tPSA was the least affected form. cPSA did not show any diagnostic superiority over other forms of PSA. Thus, serum tPSA remains a reliable parameter for follow-up of prostate cancer in uremic patients receiving long-term dialysis. However, further research is needed to explain the pathophysiology of alterations in the concentrations of different forms of PSA.

Complexed PSA performance for prostate cancer detection in an African-American population

OBJECTIVES

Complexed prostate-specific antigen (cPSA) has been shown to improve the differentiation of benign and malignant disease compared with total PSA (tPSA) in studies evaluating predominantly white populations of men. We sought to evaluate the diagnostic performance of cPSA relative to tPSA in a population of African-American men.

METHODS

Consecutive African-American men scheduled for prostate biopsy were enrolled prospectively at the Louisiana State University Medical Center, New Orleans. Serum was collected before the biopsy procedure and tested with the Immuno 1 tPSA and cPSA methods. Receiver operating characteristic curve analysis was performed and the area under the curve was calculated for tPSA and cPSA.

RESULTS

A total of 156 patients were evaluated, 51 (32.7%) of whom were diagnosed with prostate cancer. The median PSA value for men with prostate cancer was 4.96 ng/mL and for those with benign disease was 3.93 ng/mL. The receiver operating characteristic analysis indicated that the area under the curve for cPSA (0.679) was statistically greater than that achieved for tPSA (0.642, P = 0.004). Using cutoff values for cPSA of 2.3 ng/mL and for tPSA of 2.85 ng/mL provided a specificity of 31.4% and 26.7%, respectively, at a sensitivity for prostate cancer detection of 95%. This was not statistically significant (P = 0.18).

CONCLUSIONS

cPSA offers modest improvement in prostate cancer detection compared with tPSA in African-American men, but not at the clinically relevant 95% sensitivity level. Additional work is needed to improve prostate cancer detection in this high-risk cohort of patients.

Evaluation of the clinical performance of equimolar- and skewed-response total prostate-specific antigen assays versus complexed and free PSA assays and their ratios in discriminating between benign prostatic hyperplasia and prostate cancer

BACKGROUND

Prostate-specific antigen (PSA) exists in human serum in two principal forms, free PSA (fPSA) and protein-complexed PSA, predominantly PSA-ACT (alpha(1)-antichymotrypsin). Equimolar response (EMR) total PSA (tPSA) immunoassays measure each of these forms equally while skewed-response (SKR) assays overestimate or underestimate the tPSA concentration. The advantages of EMR over SKR tPSA assays are controversial.

METHODS

We used five nonhuman serum-based samples each containing a different proportion of fSPA:PSA-ACT (0:100 to 100:0, %:%) and patients' serum samples from men with histologically confirmed benign prostatic hyperplasia (BPH) (n=94) or PCA (n=30) and a wide range of fPSA concentrations to investigate the molar response status of six tPSA assays. Receiver-operator characteristic (ROC) curve analysis was used to compare the discriminatory power of these assays in distinguishing men with BPH from those with PCA.

RESULTS

The Bayer Immuno-1 tPSA (BtPSA) assay demonstrated EMR characteristics and diagnostic accuracy similar to the Hybritech Tandem-E and Tandem-R tPSA assays. At 90% sensitivity, EMR tPSA assays had higher specificity than SKR tPSA assays.

CONCLUSIONS

The BtPSA assay is an EMR tPSA assay and EMR assays provide improved diagnostic specificity over SKR tPSA assays.

Complexed prostate-specific antigen as a staging tool: results based on a multicenter prospective evaluation of complexed prostate-specific antigen in cancer diagnosis

Within a 7-site prospective evaluation of the Bayer complexed prostate-specific antigen PSA (cPSA) assay, we analyzed the ability of cPSA to predict extracapsular extension (ECE) before radical prostatectomy. Included in this analysis were 152 men diagnosed with cancer, who subsequently underwent radical prostatectomy. Sera were tested with the Bayer total PSA (tPSA) and cPSA assays, and the Beckman free PSA (fPSA) and tPSA assays. Treating surgical pathology result as a binary variable (organ confined vs ECE), mean tPSA, cPSA, fPSA/tPSA (f/tPSA) ratios, tPSA density (tPSAD), and cPSA density (cPSAD) were compared by receiver operating characteristic (ROC) curves and univariate analysis. In all, 28 men (18.4%) had pathologically identified ECE. Between those with and without ECE, significant differences were observed for tPSA (P = 0.0127), cPSA (P = 0.0120), tPSAD (P = 0.0001), and cPSAD (P = 0.0002), but not f/tPSA (P = 0.3774) or c/tPSA (P = 0.2882). All tested parameters except f/tPSA (P = 0.376) and c/tPSA (P = 0.288) predicted ECE (P <0.05) by logistic regression. The ROC area under the curve (AUC) was identical for tPSA and cPSA (0.621) and for tPSAD (0.692) and cPSAD (0.691). Kendall-tau correlation coefficients also demonstrated the strongest correlation with ECE for cPSAD and tPSAD. Either alone or as a tPSAD calculation, cPSA carries equivalent staging ability to tPSA. The use of f/tPSA appears to be less effective in staging than either cPSA or tPSA, whereas the use of either cPSAD or tPSAD provides maximal staging accuracy. Therefore, cPSA could be applied as an accurate predictor of ECE independently or in a nomogram along with other predictive variables.

Short-term stability of the molecular forms of prostate-specific antigen and effect on percent complexed prostate-specific antigen and percent free prostate-specific antigen

Differences in stability of the free and complexed molecular forms of prostate-specific antigen (PSA) may influence the clinical utility of assays for these forms, as well as the calculated ratios to total PSA (tPSA), such as percent free PSA (fPSA) and percent complexed PSA (cPSA). The objective of this study was to directly compare the short-term stability of fPSA and cPSA under different storage conditions. Specimens (3 with prostate cancer, 3 biopsy-negative without cancer, 2 normal) from 8 men were analyzed at baseline within 2 hours of collection, and at 4 hours, 8 hours, 24 hours, 48 hours, and 1 week after storage at room temperature, 4 degrees C, or -20 degrees C. Serum specimens were analyzed in duplicate on the Bayer Immuno 1 analyzer (tPSA, cPSA) and on the Beckman Coulter Access analyzer (tPSA, fPSA Tandem assays). Baseline tPSA values ranged from 0.7 to 62.0 ng/mL, with a median of 7.9 ng/mL (Immuno 1). Overall, all forms of PSA were stable up to 24 hours at the 3 temperatures, with the exception of fPSA and percent fPSA, which decreased when stored at 4 degrees C. After 1 week, tPSA levels decreased when stored at room temperature and at 4 degrees C, as did cPSA stored at room temperature. Over the 7 days, percent cPSA was stable at room temperature, but increased at 4 degrees C. There were no significant changes in any PSA form or calculated ratio with storage at -20 degrees C for up to 1 week. In summary, in the short term (<1 week), fPSA is less stable with storage than tPSA or cPSA in a time- and temperature-dependent fashion. Thus, specimen handling should be considered when interpreting PSA results. It is recommended that specimens not analyzed the same day (within 8 hours of collection) be stored frozen at -20 degrees C.

Age-related reference ranges for complexed prostate-specific antigen and complexed/total prostate-specific antigen ratio: results from East Texas Medical Center Cancer Institute screening campaign

The East Texas Medical Center Cancer Institute conducted a regional prostate cancer screening campaign over a 3-year period from 1998 through 2000. Total prostate-specific antigen (tPSA), complexed PSA (cPSA), and cPSA/tPSA ratio (c/tPSA) values were determined. To better define prostate cancer in the population, we chose to determine age-based reference ranges for these PSA isoforms in apparently healthy men. Participants (N = 12,902) between the ages of 20 and 94 were screened and demographic information and serum tPSA and cPSA values were collected across 41 centers throughout East Texas. Men with an abnormal digital rectal examination, a follow-up biopsy indicating prostatic disease, or any clinical signs and symptoms of prostatic disease were excluded. Sera from 7541 evaluable men were tested with the Bayer Immuno 1 PSA and cPSA methods at East Texas Medical Center. The resulting PSA data were then stratified by decade of age to determine age-related reference ranges for each PSA species. The cPSA values increased across all age decades: 40 to 49 years, 1.45 ng/mL; 50 to 59, 1.92 ng/mL; 60 to 69, 2.49 ng/mL; and 70 to 79, 2.77 ng/mL (95th percentile). tPSA levels also increased with age: 1.81 ng/mL, 2.45 ng/mL, 3.17 ng/mL, and 3.57, respectively. Comparatively, the c/tPSA levels remained constant (0.87), regardless of age. The upper limits of tPSA and cPSA values reported here suggest that men should be screened using lower cutoff values than are currently in use. These limits may more accurately identify prostate cancer among otherwise healthy men.

Clinical usefulness of assays for complexed prostate-specific antigen

Tests for the tumor marker prostate-specific antigen (PSA) vary widely in specificity and sensitivity. Use of an assay that tests the complexed form of PSA (cPSA) results in improved specificity and sensitivity. By improving specificity, similar results are obtained by cPSA compared with use of the free-to-total PSA ratio but are measured by a single analyte instead of two. Assays for cPSA can serve as a substitute for total PSA in all current applications.