History of the discovery and clinical translation of prostate-specific antigen

Digital Rectal Exam in Prostate Cancer Screening and Elevated PSA Work-up-Is there a role anymore?

PURPOSE OF REVIEW

Prostate cancer (PCa) screening tools, particularly digital rectal examination (DRE), are under scrutiny. This review assesses the utility of DRE in PCa screening.

RECENT FINDINGS

Recent studies reaffirm the DRE's sensitivity and specificity, a higher PCa detection rate with PSA in conjunction with DRE, and a slightly elevated risk of clinically significant PCa (CSPC) in those with elevated PSA and suspicious DRE. Studies confirm high accuracy of MRI in identifying CSPC, with ongoing research exploring its screening potential. DRE alone lacks accuracy for PCa screening, often resulting in missed diagnoses and unnecessary biopsies. Its supplementary use with PSA marginally increases detection rates of identifying a small percentage of CSPC, but the benefit remains questionable. Emerging evidence suggests MRI has the potential as a superior screening tool compared to DRE, although direct comparative studies are lacking. Overall, the DRE has a limited role in current PCa screening.

Interassay Variability and Clinical Implications of Five Different Prostate-specific Antigen Assays

Background and objective

Prostate-specific antigen (PSA) remains a critical marker for prostate cancer (PCa) detection and monitoring. Recognising historical variability in PSA assays and the evolution of assay technology and calibration, this study aims to reassess interassay variability using the latest generation of five assays in a contemporary cohort of men undergoing prostate biopsy.

Methods

Five different commercially available PSA assays were tested in a blood sample of 76 men before undergoing a prostate biopsy. Total PSA (tPSA) and free-to-total PSA ratio (%fPSA) were compared across assays, using Roche (Basel, Switzerland) as the benchmark, and correlated with biopsy outcome to analyse the impact on PCa diagnosis. The statistical analysis included Passing-Bablok regression and Bland-Altman plots, with a p value threshold of <0.05 for significance.

Key findings and limitations

Among the 76 men, 28 (36.8%) were diagnosed with significant PCa (defined as International Society of Urological Pathology grade ≥2). A high correlation was observed between tPSA and %fPSA values among the different PSA assays tested (r2 ≥ 0.9). The Passing-Bablok analysis showed that tPSA results varied substantially among the assays, with slopes ranging between 0.78 and 1.04. Compared with the tPSA of Roche, tPSA values were on average 20.7% lower by Beckman (Oststeinbeck, Germany), 15.2% lower by Abbott (Chicago, IL, USA), 6.1% lower by Diasorin (Saluggia, Italy), and 9.6% higher by Brahms (Hennigsdorf, Germany; p < 0.001 for all). The %fPSA values by Abbott and Brahms were higher at 15.7% and 10.6%, respectively (p < 0.001), while the Beckman and Diasorin values had minimal differences of -0.3% and 2.3%, respectively (p > 0.05). The variability across assays would have resulted in discrepancies in both the sensitivity and the specificity for tPSA and %fPSA by at least 14%, depending on the cut-offs applied.

Conclusions and clinical implications

Despite the use of the latest PSA assays, relevant variability of tPSA and %fPSA results can be observed among different assays. There is an urgent need for standardised calibration methods and greater awareness among practitioners concerning interassay variability. Clinicians should acknowledge that clinically relevant thresholds may depend on the specific PSA assay and that ideally the same assay is applied over time for better clinical decision-making.

Patient summary

Prostate-specific antigen (PSA) is a critical marker for prostate cancer (PCa) detection and monitoring. However, significant variations were observed in the results of the latest PSA assays. Thus, standardised calibration methods and greater awareness among practitioners concerning interassay variability are needed.

Health Policy for Prostate Cancer Early Detection in the European Union and the Impact of Opportunistic Screening: PRAISE-U Consortium

With the new policy recommendation in 2022 to explore the possibilities of screening for prostate cancer by the European Commission, the landscape for prostate cancer early detection is evolving. In line with this recommendation, the PRAISE-U project aims to evaluate the early detection and diagnosis of prostate cancer through customised and risk-based screening programmes, with the goal to align protocols across European Union member states. This systematic review is part of the PRAISE-U project, with the goal to review the policy, medical guideline recommendations, and the current level of opportunistic screening presented in the scientific literature on prostate cancer early detection from 2016 to 2023 in European Union member states. An extensive literature search was performed on 1 June 2023 in a large number of databases, including Embase.com, Medline (Ovid), Web of Science Core Collection, Google Scholar, and Policy Commons. We identified 318 articles (qualitative, quantitative, and reviews), of which 41 were included in the full-text screening. Seventeen articles were ultimately identified as eligible for inclusion. The included articles revealed significant variations towards PSA-based early detection policies for prostate cancer in nine European countries. Despite official recommendations, opportunistic screening was prevalent across all nine countries regardless of recommendations for or against PSA-based early detection. This systematic review suggests that the current early detection policies are not fit for purpose. High levels of opportunistic screening and overdiagnosis persist, prompting policy recommendations for standardised guidelines, informed decision making, and increased awareness to improve efficiency and effectiveness in early detection.

Portable and Rapid Dual-Biomarker Detection Using Solution-Gated Graphene Field Transistors in the Accurate Diagnosis of Prostate Cancer

Prostate-specific antigen (PSA) is the common serum-relevant biomarker for early prostate cancer (PCa) detection in clinical diagnosis. However, it is difficult to accurately diagnose PCa in the early stage due to the low specificity of PSA. Herein, a new solution-gated graphene field transistor (SGGT) biosensor with dual-gate for dual-biomarker detection is designed. The sensing mechanism is that the designed aptamers immobilized on the surface of the gate electrodes can capture PSA and sarcosine (SAR) biomolecules and induce the capacitance changes of the electric double layers of SGGT. The limit of detections of PSA and SAR biomarkers can reach 0.01 fg mL-1 , which is three-to-four orders of magnitude lower than previously reported assays. The detection time of PSA and SAR is ≈4.5 and ≈13 min, which is significantly faster than the detection time (1-2 h) of conventional methods. The clinical serum samples testing demonstrates that the biosensor can distinguish the PCa patients from the control group and the diagnosis accuracy can reach 100%. The SGGT biosensor can be integrated into the portable platform and the diagnostic results can directly display on the smartphone/Pad. Therefore, the integrated portable platform of the biosensor can distinguish cancer types through the dual-biomarker detection.

Serum prostate specific antigen is a good indicator of prostatic volume in men with benign prostatic hyperplasia

BACKGROUND

Benign prostatic hyperplasia (BPH) is the most common cause of bladder outlet obstruction in men over the age of 50 years. An association between the prostate specific antigen (PSA), International Prostate Symptoms Score (IPSS) and prostate volume (PV) may be instrumental in determining patients who may benefit from treatment. Targeted therapy will reduce the cost of care because it is unwise to treat all men with prostate enlargement to prevent complications when the risk of occurrence is negligible.

AIM

To determine the correlation between the PSA, IPSS and PV in men of African descent.

SETTING

This was a cross sectional analysis involving 92 patients diagnosed as having symptomatic BPH at the Ho Teaching Hospital.

METHODS

The data were collected using standardised questionnaires. The IPSS determined urinary symptom severity. The PV was determined using a transabdominal ultrasound machine. Serum PSA was retrieved from the electronic medical records.

RESULTS

The mean PV was 61.04 cm3 ± 21.95 cm3, the mean PSA was 4.21 ng/mL ± 3.85 ng/mL, and mean IPSS of 21.59 ± 3.78. The Pearson's correlation between PV and PSA was 0.283 (p = 0.01), between PV and IPSS was 0.108 (p = 0.30), and finally, between Serum PSA and IPSS Score was -0.086 (p = 0.42).

CONCLUSION

This study showed that serum PSA has a positive correlation with PV. However, IPSS had no significant association with PSA or PV in patients with BPH.Contribution: This study provides insights into the implications of clinical parameters on the management of prostate enlargement.

Multicancer Early Detection Technologies: A Review Informed by Past Cancer Screening Studies

More than 75% of cancer-related deaths occur from cancers for which we do not screen. New screening liquid biopsies may help fill these clinical gaps, although evidence of benefit still needs to be assessed. Which lessons can we learn from previous efforts to guide those of the future? Screening trials for ovarian, prostate, pancreatic, and esophageal cancers are revisited to assess the evidence, which has been limited by small effect sizes, short duration of early-stage disease relative to screening frequency, study design, and confounding factors. Randomized controlled trials (RCT) to show mortality reduction have required millions of screening-years, two-decade durations, and been susceptible to external confounding. Future RCTs with late-stage incidence as a surrogate endpoint could substantially reduce these challenges, and clinical studies demonstrating safety and effectiveness of screening in high-risk populations may enable extrapolation to broader average-risk populations. Multicancer early detection tests provide an opportunity to advance these practical study designs. Conditional approvals based on RCTs with surrogate endpoints, contingent upon real world evidence generation and continuation of trials to definitive endpoints, may lower practical barriers to innovation in cancer screening and enable greater progress.

The Relationship Between PSA and Total Testosterone Levels in Men With Prostate Cancer

BACKGROUND

Prostate-specific antigen (PSA) secretion is a testosterone (T) dependent process. Published data suggest that a low T level is an independent predictor of higher-grade prostate cancer (PC).

AIM

To evaluate the relationship between T and PSA in patients with PC.

METHODS

All men diagnosed with PC with a recorded pre-treatment total T level measurement were included in this analysis. We analyzed demographic, clinical, and pathological data. Patients were stratified according to pretreatment PSA levels: <2 ng/mL, 2-4 ng/mL, >4 ng/mL. Low T was defined as total T < 10.4 nmol/L (300 ng/dL), very low T < 6.9 nmol/L (200 ng/dL).

OUTCOMES

T levels by PSA groups according to the PC pathology.

RESULTS

In this retrospective study, mean patient age was 61 years among 646 men. The distribution by PSA group was: 8% (<2), 17% (2-4), and 76% (>4). The mean T level across the entire cohort was 13 nmol/L (374 ng/dL). Overall, 30% had a T level < 10.4 nmol/L (300 ng/dL). The mean total T level by PSA group was: <2 ng/mL, 7 nmol/L (206 ng/dL); 2-4 ng/mL, 13 nmol/L (362 ng/dL); >4 ng/mL, 14 nmol/L (393 ng/dL), P < .001. PSA <4 ng/mL was a significant predictor of low T in men with PC GS ≥8. PSA <2 ng/mL was a significant predictor of very low T independent of the PC pathology.

CLINICAL IMPLICATIONS

These findings suggest that clinicians should consider measuring T levels when a patient diagnosed with PC GS ≥8 and PSA level <4 ng/mL, and for each patient with PSA level <2 ng/mL independent of the PC pathology.

STRENGTHS & LIMITATIONS

Our study has several strengths including (i) inclusion of a large population of men, (ii) use of a database which is audited and reviewed for accuracy annually, and (iii) use of an accurate T assay (LCMS). Nonetheless, there are limitations: (i) the subjects of the study are from a single institution, and (ii) we did not measure free T levels.

CONCLUSION

In men with PC with GS ≥8, PSA level <4 ng/mL predicts low T. PSA <2 ng/mL predicts very low T independent of the PC pathology. Flores JM, Bernie HL, Miranda E, et al. The Relationship Between PSA and Total Testosterone Levels in Men With Prostate Cancer. J Sex Med 2022;19:471-478.

SERPIN A5 may have a potential as a biomarker in reflecting the improvement of semen quality in infertile men who underwent varicocele repair

We aimed to identify proteins that were differentially regulated in spermatozoal samples collected from fertile healthy men (FHM) and infertile patients with varicocele (IFPV) before and after varicocelectomy. Seminal samples were collected from 20 IFPV before and after varicocelectomy and from 14 FHM as controls. Samples underwent seminal examination and proteomic analysis. Extracted spermatozoal proteins were analysed using two-dimensional gel electrophoresis, and differentially regulated spermatozoal proteins (DRSPs) were identified. In particular, attention was placed on those DRSPs in which the concentration changed after varicocelectomy and corrected to approximate levels observed in FHM. Varicocelectomy significantly improved the sperm count and concentration in IFPV (p < 0.05). Proteomic analysis showed that 11 DRSPs were identified when comparisons were made among the three groups. Among these 11 proteins, change in the SERPIN A5 concentrations was notable because it was 100-fold downregulated in pre-operative IFPV samples and nearly resembled to control concentrations following varicocelectomy. Western blot analysis using an anti-SERPIN antibody validated the changes observed in SERPIN A5 levels before and after varicocelectomy operation. Increase in SERPIN A5 after varicocelectomy may be due to improvement in semen quality, suggesting that SERPIN A5 is a potential seminal biomarker for assessment of semen quality in varicocele-related infertility.

Metastatic Spread in Prostate Cancer Patients Influencing Radiotherapy Response

Radiotherapy and surgery are curative treatment options for localized prostate cancer (PCa) with a 5-year survival rate of nearly 100%. Once PCa cells spread into distant organs, such as bone, the overall survival rate of patients drops dramatically. The metastatic cascade and organotropism of PCa cells are regulated by different cellular subtypes, organ microenvironment, and their interactions. This cross-talk leads to pre-metastatic niche formation that releases chemo-attractive factors enforcing the formation of distant metastasis. Biological characteristics of PCa metastasis impacting on metastatic sites, burden, and latency is of clinical relevance. Therefore, the implementation of modern hybrid imaging technologies into clinical routine increased the sensitivity to detect metastases at earlier stages. This enlarged the number of PCa patients diagnosed with a limited number of metastases, summarized as oligometastatic disease. These patients can be treated with androgen deprivation in combination with local-ablative radiotherapy or radiopharmaceuticals directed to metastatic sites. Unfortunately, the number of patients with disease recurrence is high due to the enormous heterogeneity within the oligometastatic patient population and the lack of available biomarkers with predictive potential for metastasis-directed radiotherapy. Another, so far unmet clinical need is the diagnosis of minimal residual disease before onset of clinical manifestation and/or early relapse after initial therapy. Here, monitoring of circulating and disseminating tumor cells in PCa patients during the course of radiotherapy may give us novel insight into how metastatic spread is influenced by radiotherapy and vice versa. In summary, this review critically compares current clinical concepts for metastatic PCa patients and discuss the implementation of recent preclinical findings improving our understanding of metastatic dissemination and radiotherapy resistance into standard of care.

Hematologic parameters are not predictors of upgrading or treatment in a racially diverse prospective study of men with prostate cancer on active surveillance

INTRODUCTION

Neutrophil-to-lymphocyte (NLR) and platelet-to-lymphocyte ratios (PLR) are useful clinical biomarkers for prognosis in several malignancies. Their predictive value has been less clearly demonstrated with prostate cancer (PCa), particularly, their utility within active surveillance (AS) protocols. We aim to evaluate NLR and PLR in AS patients.

METHODS

We identified 98 patients who met inclusion criteria in our cohort of 274 men diagnosed with PCa on AS. Patients were then categorized into high and low NLR and PLR groups.

RESULTS

The 2.5 and 5-year Gleason upgrading free probability for our high NLR cohort was 73.9%(CI 56.3% to 97.0%) and 46.2%(CI 22.4% to 95.1%) compared to 76.3%(CI 65.7% to 88.7%) and 61.7%(CI 47.7% to 80.0%) in the low NLR cohort(p = .73). The 2.5 and 5-year Gleason upgrading free probability for our High PLR cohort was 73.5%(CI 57.3% to 94.2%) and 60.1(CI 41.4% to 87.4%) compared to 76.8%(CI 65.8% to 89.65) and 58.1%(CI 42.2% to 80.1%) in our low PLR group(p = .41). A multivariant analysis demonstrated these groups were not significant predictors of upgrading or treatment.

CONCLUSION

Despite their usefulness in many types of malignancy, NLR and PLR were not predictors of upgrading or treatment in men on AS for localized PCa in our cohort.

Rate of diagnostic errors and serious misdiagnosis-related harms for major vascular events, infections, and cancers: toward a national incidence estimate using the “Big Three”

Background

Missed vascular events, infections, and cancers account for ~75% of serious harms from diagnostic errors. Just 15 diseases from these “Big Three” categories account for nearly half of all serious misdiagnosis-related harms in malpractice claims. As part of a larger project estimating total US burden of serious misdiagnosis-related harms, we performed a focused literature review to measure diagnostic error and harm rates for these 15 conditions.

Methods

We searched PubMed, Google, and cited references. For errors, we selected high-quality, modern, US-based studies, if available, and best available evidence otherwise. For harms, we used literature-based estimates of the generic (disease-agnostic) rate of serious harms (morbidity/mortality) per diagnostic error and applied claims-based severity weights to construct disease-specific rates. Results were validated via expert review and comparison to prior literature that used different methods. We used Monte Carlo analysis to construct probabilistic plausible ranges (PPRs) around estimates.

Results

Rates for the 15 diseases were drawn from 28 published studies representing 91,755 patients. Diagnostic error (false negative) rates ranged from 2.2% (myocardial infarction) to 62.1% (spinal abscess), with a median of 13.6% [interquartile range (IQR) 9.2–24.7] and an aggregate mean of 9.7% (PPR 8.2–12.3). Serious misdiagnosis-related harm rates per incident disease case ranged from 1.2% (myocardial infarction) to 35.6% (spinal abscess), with a median of 5.5% (IQR 4.6–13.6) and an aggregate mean of 5.2% (PPR 4.5–6.7). Rates were considered face valid by domain experts and consistent with prior literature reports.

Conclusions

Diagnostic improvement initiatives should focus on dangerous conditions with higher diagnostic error and misdiagnosis-related harm rates.

A novel bioassay for the monitoring of carcinoembryonic antigen in human biofluid using polymeric interface and immunosensing method

Carcinoembryonic antigen (CEA) is a member of a family of cell surface glycoproteins. Recognition of CEA is needed to monitor the physiological status of the patient for treatment and also it is important to assess the severity of the disease. In this work, we reported a novel sandwich-type electrochemical immunosensor based on gold nanoparticles functionalized cysteamine-glutaraldehyde (AuNPs-CysA-GA) and it successfully designed to detection of the CEA biomarker in a human plasma sample. The AuNPs-CysA-GA provides a large surface area for the effective immobilization of CEA antibody, as well as it ascertains the bioactivity and stability of immobilized CEA antigens. Biotinylated-anti-CEA antibody (Ab1) was immobilized on the surface of glassy carbon electrode (GCE) modified AuNPs-CysA-GA. Also, secondary antibody (HRP-Ab2) was costed immobilized to complete the sandwich part of immunosensor. Field emission scanning electron microscope (FE-SEM and EDS), was employed to monitor the sensor fabrication procedure. The immunosensor was used for the detection of CEA using differential pulse voltammetry (DPVs) technique. The proposed interface led to enhancement of accessible surface area for immobilizing high amount of anti-CEA antibody, increasing electrical conductivity, boosting stability, and biocompatibility. Finally, the low limit of quantitation (LLOQ) of the proposed immunosensor was obtained as 7 ng/mL with the linear range of 0.001-5 μg/L. The proposed immunoassay was successfully applied for the monitoring of the CEA in unprocessed human plasma samples. Obtained results paved that the proposed bioassay can be used as a novel bioassay for the clinical diagnosis of cancer based on CEA monitoring.

Combined analysis and validation for DNA methylation and gene expression profiles associated with prostate cancer

BACKGROUND

Prostate cancer (PCa) is a malignancy cause of cancer deaths and frequently diagnosed in male. This study aimed to identify tumor suppressor genes, hub genes and their pathways by combined bioinformatics analysis.

METHODS

A combined analysis method was used for two types of microarray datasets (DNA methylation and gene expression profiles) from the Gene Expression Omnibus (GEO). Differentially methylated genes (DMGs) were identified by the R package minfi and differentially expressed genes (DEGs) were screened out via the R package limma. A total of 4451 DMGs and 1509 DEGs, identified with nine overlaps between DMGs, DEGs and tumor suppressor genes, were screened for candidate tumor suppressor genes. All these nine candidate tumor suppressor genes were validated by TCGA (The Cancer Genome Atlas) database and Oncomine database. And then, the gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) enrichment analyses were performed by DAVID (Database for Annotation, Visualization and Integrated Discovery) database. Protein-protein interaction (PPI) network was constructed by STRING and visualized in Cytoscape. At last, Kaplan-Meier analysis was performed to validate these genes.

RESULTS

The candidate tumor suppressor genes were IKZF1, PPM1A, FBP1, SMCHD1, ALPL, CASP5, PYHIN1, DAPK1 and CASP8. By validation in TCGA database, PPM1A, DAPK1, FBP1, PYHIN1, ALPL and SMCHD1 were significant. The hub genes were FGFR1, FGF13 and CCND1. These hub genes were identified from the PPI network, and sub-networks revealed by these genes were involved in significant pathways.

CONCLUSION

In summary, the study indicated that the combined analysis for identifying target genes with PCa by bioinformatics tools promote our understanding of the molecular mechanisms and underlying the development of PCa. And the hub genes might serve as molecular targets and diagnostic biomarkers for precise diagnosis and treatment of PCa.

A novel classification of prostate specific antigen (PSA) biosensors based on transducing elements

During the last few decades, there has been a tremendous rise in the number of research studies dedicated towards the development of diagnostic tools based on bio-sensing technology for the early detection of various diseases like cardiovascular diseases (CVD), many types of cancer, diabetes mellitus (DM) and many infectious diseases. Many breakthroughs have been developed in the areas of improving specificity, selectivity and repeatability of the biosensor devices. Innovations in the interdisciplinary areas like biotechnology, genetics, organic electronics and nanotechnology also had a great positive impact on the growth of bio-sensing technology. As a product of these improvements, fast and consistent sensing policies have been productively created for precise and ultrasensitive biomarker-based disease diagnostics. Prostate-specific antigen (PSA) is widely considered as an important biomarker used for diagnosing prostate cancer. There have been many publications based on various biosensors used for PSA detection, but a limited review was available for the classification of these biosensors used for the detection of PSA. This review highlights the various biosensors used for PSA detection and proposes a novel classification for PSA biosensors based on the transducer type used. We also highlight the advantages, disadvantages and limitations of each technique used for PSA biosensing which will make this article a complete reference tool for the future researches in PSA biosensing.

Age-Specific Cutoff Value for the Application of Percent Free Prostate-Specific Antigen (PSA) in Chinese Men with Serum PSA Levels of 4.0-10.0 ng/ml

OBJECTIVE

The influence of age on the performance of percent free prostate-specific antigen (%fPSA) in diagnosing prostate cancer (PCa) in East Asians is controversial. We tested the diagnostic performance of %fPSA in a multi-center biopsy cohort in China and identified the proper age-specific cutoff values to avoid unnecessary biopsies.

METHODS

Consecutive patients with a prostate-specific antigen (PSA) level of 4.0-10.0 ng/ml or 10.1-20.0 ng/ml who underwent transrectal ultrasound-guided or transperineal prostate biopsy were enrolled from 22 Chinese medical centers from Jan 1, 2010 to Dec 31, 2013. The diagnostic accuracy of PSA and %fPSA was determined using the area under the receiver operating characteristic (ROC) curve (AUC). Age-specific cutoff values were calculated using ROC curve analysis.

RESULTS

The median %fPSA was much lower in younger patients compared with older patients with a PSA level of 4.0-10.0 ng/ml or 10.1-20.0 ng/ml. The AUC of %fPSA was higher than PSA only in older patients. In patients aged 50 to 59 years, %fPSA failed to improve the diagnosis compared with PSA in these two PSA ranges. Age-specific cutoff values were 24%, 27% and 32% for patients aged 60-69, 70-79 and ≥80 years, respectively, to reduce unnecessary biopsies in men with PSA levels of 4.0-10.0 ng/ml to detect 90% of all PCa.

CONCLUSIONS

The effectiveness of %fPSA is correlated with age in the Chinese population. Age-specific cutoff values would help avoid unnecessary biopsies in the Chinese population.