Screening for prostate cancer: early detection or overdetection?

Intracellular MicroRNA Imaging and Specific Discrimination of Prostate Cancer Circulating Tumor Cells Using Multifunctional Gold Nanoprobe-Based Thermophoretic Assay

Circulating tumor cells (CTCs) have emerged as powerful biomarkers for diagnosis of prostate cancer. However, the effective identification and concurrently accurate imaging of CTCs for early screening of prostate cancer have been rarely explored. Herein, we reported a multifunctional gold nanoprobe-based thermophoretic assay for simultaneous specific distinguishing of prostate cancer CTCs and sensitive imaging of intracellular microRNA (miR-21), achieving the rapid and precise detection of prostate cancer. The multifunctional gold nanoprobe (GNP-DNA/Ab) was modified by two types of prostate-specific antibodies, anti-PSMA and anti-EpCAM, which could effectively recognize the targeting CTCs, and meanwhile linked double-stranded DNA for further visually imaging intracellular miR-21. Upon the specific internalization of GNP-DNA/Ab by PC-3 cells, target aberrant miR-21 could displace the signal strand to recover the fluorescence signal for sensitive detection at the single-cell level, achieving single PC-3 cell imaging benefiting from the thermophoresis-mediated signal amplification procedure. Taking advantage of the sensitive miR-21 imaging performance, GNP-DNA/Ab could be employed to discriminate the PC-3 and Jurkat cells because of the different expression levels of miR-21. Notably, PC-3 cells were efficiently recognized from white blood cells, exhibiting promising potential for the early diagnosis of prostate cancer. Furthermore, GNP-DNA/Ab possessed good biocompatibility and stability. Therefore, this work provides a great tool for aberrant miRNA-related detection and specific discrimination of CTCs, achieving the early and accurate diagnosis of prostate cancer.

Finding the PSA-based screening stopping age using prostate cancer risk

BACKGROUND

Prostate Cancer screening was not rational for people who were suffered from other serious diseases and had a low quality of life. Biopsy and Prostate-Specific Antigen based screening also had imperfect information, pain, and costs. Finding the Prostate Cancer screening stopping age was important because after an age, Prostate-Specific Antigen test was not recommended and patients should not perform subsequent procedures. It could reduce the economic burden of Prostate Cancer. In this study, we modeled the effects of Prostate Cancer risk and comorbidities on the Prostate Cancer screening stopping age.

METHODS

first, using a Markov model for PC progression, we provided a model for optimal Prostate Cancer screening stopping age. Second, we explored the relationship between comorbidities effects, Prostate Cancer risk and the stopping age.

RESULTS

Our results suggest that the stopping age was an increasing function of PC risk and comorbidities effects. Screening should be stopped before 70 years. Finding showed that for men with diseases such as stroke or heart diseases, screening should not be performed at any age.

CONCLUSIONS

Personalizing PC screening through paying more attention to PC risk can improve efficiency of screening. The role of personal characteristics such as race, family history, and previous PSA in PC screening decision-making was highlighted by stratifying men in different PC risk groups to find their stopping age. Incorporating comorbidity effects shows that severity of comorbidity was a crucial factor in PC screening stopping age decision-making process.

Health-related quality of life among prostate cancer survivors with metastatic disease and non-metastatic disease and men without a cancer history in the USA

BACKGROUND

Few studies have comprehensively compared health-related quality of life (HRQoL) between metastatic prostate cancer survivors, survivors with non-metastatic disease, and men without a cancer history.

METHODS

We used the Surveillance, Epidemiology, and End Results-Medicare Health Outcomes Survey (SEER-MHOS) data linkage to identify men aged ≥ 65 years enrolled in Medicare Advantage (MA) plans. Prostate cancer survivors were diagnosed between 1988 and 2017 and completed MHOS surveys between 1998 and 2019. We analyzed data from 752 metastatic prostate cancer survivors (1040 survey records), 19,583 localized or regional prostate cancer survivors (non-metastatic; 30,121 survey records), and 784,305 men aged ≥ 65 years without a cancer history in the same SEER regions (1.15 million survey records). We used clustered linear regressions to compare HRQoL measures at the person-level using the Veterans RAND 12 Item Health Survey (VR-12) T-scores for general health and physical and mental component summaries.

RESULTS

Compared to men without a cancer history, prostate cancer survivors were older, more likely to be married, and had higher socioeconomic status. Compared to men without a cancer history, metastatic prostate cancer survivors reported lower general health (T-score differences [95% confidence interval]: - 6.26, [- 7.14, - 5.38], p < .001), physical health (- 4.33, [- 5.18, - 3.48], p < .001), and mental health (- 2.64, [- 3.40, - 1.88], p < .001) component summaries. Results were similar for other VR-12 T-scores. In contrast, non-metastatic prostate cancer survivors reported similar VR-12 T-scores as men without a cancer history. Further analyses comparing metastatic and non-metastatic prostate cancer survivors support these findings.

CONCLUSION

Interventions to improve health-related quality of life for men diagnosed with metastatic prostate cancer merit additional investigation.

IMPLICATIONS FOR CANCER SURVIVORS

Interventions to improve health-related quality of life for metastatic prostate cancer survivors merit additional investigation.

Cardiovascular mortality by cancer risk stratification in patients with localized prostate cancer: a SEER-based study

Purpose

The risk of cardiovascular disease (CVD) mortality in patients with localized prostate cancer (PCa) by risk stratification remains unclear. The aim of this study was to determine the risk of CVD death in patients with localized PCa by risk stratification.

Patients and methods

Population-based study of 340,806 cases in the Surveillance, Epidemiology, and End Results (SEER) database diagnosed with localized PCa between 2004 and 2016. The proportion of deaths identifies the primary cause of death, the competing risk model identifies the interaction between CVD and PCa, and the standardized mortality rate (SMR) quantifies the risk of CVD death in patients with PCa.

Results

CVD-related death was the leading cause of death in patients with localized PCa, and cumulative CVD-related death also surpassed PCa almost as soon as PCa was diagnosed in the low- and intermediate-risk groups. However, in the high-risk group, CVD surpassed PCa approximately 90 months later. Patients with localized PCa have a higher risk of CVD-related death compared to the general population and the risk increases steadily with survival (SMR = 4.8, 95% CI 4.6-5.1 to SMR = 13.6, 95% CI 12.8-14.5).

Conclusions

CVD-related death is a major competing risk in patients with localized PCa, and cumulative CVD mortality increases steadily with survival time and exceeds PCa in all three stratifications (low, intermediate, and high risk). Patients with localized PCa have a higher CVD-related death than the general population. Management of patients with localized PCa requires attention to both the primary cancer and CVD.

Radiomics vs radiologist in prostate cancer. Results from a systematic review

PURPOSE

Radiomics in uro-oncology is a rapidly evolving science proving to be a novel approach for optimizing the analysis of massive data from medical images to provide auxiliary guidance in clinical issues. This scoping review aimed to identify key aspects wherein radiomics can potentially improve the accuracy of diagnosis, staging, and extraprostatic extension in prostate cancer (PCa).

METHODS

The literature search was performed on June 2022 using PubMed, Embase, and Cochrane Central Controlled Register of Trials. Studies were included if radiomics were compared with radiological reports only.

RESULTS

Seventeen papers were included. The combination of PIRADS and radiomics score models improves the PIRADS score reporting of 2 and 3 lesions even in the peripheral zone. Multiparametric MRI-based radiomics models suggest that by simply omitting diffusion contrast enhancement imaging in radiomics models can simplify the process of analysis of clinically significant PCa by PIRADS. Radiomics features correlated with the Gleason grade with excellent discriminative ability. Radiomics has higher accuracy in predicting not only the presence but also the side of extraprostatic extension.

CONCLUSIONS

Radiomics research on PCa mainly uses MRI as an imaging modality and is focused on diagnosis and risk stratification and has the best future possibility of improving PIRADS reporting. Radiomics has established its superiority over radiologist-reported outcomes but the variability has to be taken into consideration before translating it to clinical practice.

Caveat Medicus: It's Time to Re-Think Stratification, You May Not Be Helping

Background

The focus of the present Letter is on the large and seemingly fertile body of work captured under the umbrella of 'patient stratification'.

Objectives

I identify and explain a fundamental methodological flaw underlying the manner in which the development of an increasingly large number of new stratification strategies is approached.

Design

I show an inherent conflict between the assumptions made, and the very purpose of stratification and its application in practice.

Methods

I analyse the methodological underpinnings of stratification as presently done and draw parallels with conceptually similarly flawed precedents which are now widely recognized.

Results

The highlighted flaw is shown to undermine the overarching ultimate goal of improved patient outcomes by undue fixation on an ill-founded proxy.

Conclusion

I issue a call for a re-think of the problem and the processes leading to the adoption of new stratification strategies in the clinic.

The accuracy of prostate cancer diagnosis in biopsy-naive patients using combined magnetic resonance imaging and transrectal ultrasound fusion-targeted prostate biopsy

Background

This study aimed to estimate whether multiparametric magnetic resonance imaging (mpMRI)-transrectal ultrasound (TRUS) fusion biopsy (FUS-TB) increases the detection rates of clinically significant prostate cancer (csPCa) compared with TRUS-guided systematic biopsy (TRUS-GB).

Methods

This retrospective study focused on patients who underwent mpMRI before prostate biopsy (PB) with Prostate Imaging Reporting and Data System version 2 (PI-RADS v2) scores ≥3 and prostate-specific antigen (PSA) level between 2.5 and 20 ng/mL. Before FUS-TB, the biopsy needle position was checked virtually using three-dimensional mapping. After confirming the position of the target within the prostate, biopsy needle was inserted and PB was performed. Suspicious lesions were generally targeted with 2 to 4 cores. Subsequently, 10–12 cores were biopsied for TRUS-GB. The primary endpoint was the PCa detection rate (PCDR) for patients with PCa who underwent combined FUS-TB and TRUS-GB.

Results

According to PI-RADS v2, 76.7% of the patients with PI-RADS v2 score ≥3 were diagnosed with PCa. The PCDRs in patients with PI-RADS v2 score of 4 or 5 were significantly higher than those in patients with PI-RADS v2 score of 3 (3 vs. 4, P<0.001; 3 vs. 5, P<0.001; 4 vs. 5, P=0.073). According to PCDR, the detection rates of PCa and csPCa in the FUS-TB were significantly higher than that in the TRUS-GB.

Conclusions

Following detection of suspicious tumor lesions on mpMRI, FUS-TB use detects a higher number of PCa cases compared with TRUS-GB.

Contrast-enhanced transrectal ultrasound can reduce collection of unnecessary biopsies when diagnosing prostate cancer and is predictive of biochemical recurrence following a radical prostatectomy in patients with localized prostate cancer

Background

To investigate the value of using contrast-enhanced transrectal ultrasound (CETRUS) to reduce unnecessary collection of biopsies during prostate cancer diagnosis and its utility in predicting biochemical recurrence in patients with localized prostate cancer.

Methods

This was a prospective study of suspected prostate cancer patients who were evaluated with CETRUS followed by a prostate biopsy. Prostate blood flow via CETRUS was graded using a 5-point scale. The relationship between CETRUS score and biopsy outcome was then analyzed for all patients; univariate and multi-variate analyses were used to determine the probable prognostic factors for biochemical recurrence in patients with localized prostate cancer that underwent a radical prostatectomy.

Results

A total of 347 patients were enrolled in the study. Prostate cancer was found in 164 patients. A significant positive correlation (r = 0.69, p < 0.001) was found between CETRUS scores and prostate cancer incidence. Using CETRUS scores ≥2 as the threshold for when to biopsy could have safely reduced the number of biopsies taken overall by 12.1% (42/347) and spared 23.0% (42/183) of patients from undergoing an unnecessary biopsy. 77 patients with localized prostate cancer underwent a radical prostatectomy. The median follow-up time was 30 months (range: 8–56 months) and 17 of these 77 patients exhibited biochemical recurrence during the follow-up period. 3-year biochemical recurrence-free survival rates were 86% for patients with low CETRUS scores (≤ 3) and 59% for patients with high scores (> 3; p = 0.015). Multivariate Cox regression analysis indicated that CETRUS score was an independent predictor of biochemical recurrence (HR: 7.02; 95% CI: 2.00–24.69; p = 0.002).

Conclusions

CETRUS scores may be a useful tool for reducing the collection unnecessary biopsy samples during prostate cancer diagnosis and are predictive of biochemical recurrence in patients with localized prostate cancer following a radical prostatectomy.

Ethnic variation in prostate cancer detection: a feasibility study for use of the Stockholm3 test in a multiethnic U.S. cohort

BACKGROUND

The Stockholm3 test improves Gleason Grade Group ≥2 (GG ≥ 2) prostate cancer (PC) detection, however it has not been evaluated in an American cohort where clinical practice patterns and ethnicity differ. We aimed to identify subgroups within a Stockholm population with PC risk profiles matching American ethnicity-specific subgroups and compare the detection of PC and describe Stockholm3 performance within these subgroups.

METHODS

All men age 49-70 years presenting for prostate biopsies were evaluated at UIC from 2016 to 2019, as well as men in Stockholm from 2012 to 2014 in the STHLM3 study. Propensity scores (PS) were estimated for each person using logistic regression for age, PSA, prostate volume, family history of PC, 5-alpha reductase inhibitor use, and prior biopsy. 3:1 PS matching was performed for Stockholm to Chicago ethnicity-specific cohorts and odds ratios (OR) were computed to compare detection of GG ≥ 2 PC between groups.

RESULTS

504 Chicago men and 6980 Stockholm men were included. In African American (AA) men, 51% had GG ≥ 2 PC detected, while in risk-matched Stockholm men, 34% had GG ≥ 2 PC detected (OR: 2.1, p < 0.001). There was no statistical difference in GG ≥ 2 PC detected when matching Stockholm men to non-Hispanic Caucasian men (31% vs. 24%, OR: 0.7, p = 0.30) or Hispanic Caucasian men (31% vs. 27%, OR: 1.2, p = 0.42). The AUC for the Stockholm3 test of the matched Stockholm cohorts for AA, non-Hispanic Caucasian, and Hispanic Caucasian men was 0.85, 0.89, and 0.90, respectively.

CONCLUSIONS

Using statistical techniques to simulate a multi-ethnic Chicago cohort within the STHLM3 population, we found an excess risk of GG ≥ 2 PC among AA men. Our hypothesis that the Stockholm3 may have good predictive value in a multiethnic cohort is strengthened, and that recalibration to at least AA men seems likely to be needed to obtain well-calibrated predictions.

Cost-Effectiveness Analysis of Prostate-Specific Antigen Screening Among Chinese Men

OBJECTIVES

To analyze the cost-effectiveness of prostate cancer screening among Chinese men.

METHODS

A cost-effectiveness analysis was performed from a societal perspective using a Markov model to compare 2 strategies: the population-based screening strategy and the current clinical diagnostic strategy. Relevant parameters were retrieved from published literature data and surveys, and univariate sensitivity analysis was used to assess the robustness of the model. We simulated the health outcomes for the next 25 years for 100 000 men and calculated the incremental cost-effectiveness ratio (ICER).

RESULTS

This study found that the population-based screening strategy, compared with the clinical diagnostic strategy, could save 756.61 quality-adjusted life-years (QALYs) for the hypothetical population. The ICER for the population-based screening strategy was ¥14 747.11/QALY, and this value was less than the willingness-to-pay threshold of ¥64 520. With life-year gains (LYGs) as the model output, the population-based screening strategy yielded an ICER of ¥16 470.45/LYG. The univariate sensitivity analyses showed that the ICER was sensitive to the prostate-specific antigen (PSA) test fee, the proportion diagnosed with low-grade prostate cancer (PC) in the population-based strategy, and the proportion diagnosed with intermediate-grade PC in the population-based strategy.

CONCLUSIONS

Prostate cancer screening based on PSA test results appears to be cost-effective for Chinese men who are in good health and have a life expectancy of more than 10 years. Nevertheless, this finding needs to be further studied with more treatment cost parameters (treatment costs related to impotence and urinary incontinence) and using local utility value information.

Elevated Tumor Lactate and Efflux in High-grade Prostate Cancer demonstrated by Hyperpolarized 13C Magnetic Resonance Spectroscopy of Prostate Tissue Slice Cultures

Non-invasive assessment of the biological aggressiveness of prostate cancer (PCa) is needed for men with localized disease. Hyperpolarized (HP) ¹³C magnetic resonance (MR) spectroscopy is a powerful approach to image metabolism, specifically the conversion of HP [1-¹³C]pyruvate to [1-¹³C]lactate, catalyzed by lactate dehydrogenase (LDH). Significant increase in tumor lactate was measured in high-grade PCa relative to benign and low-grade cancer, suggesting that HP ¹³C MR could distinguish low-risk (Gleason score ≤3 + 4) from high-risk (Gleason score ≥4 + 3) PCa. To test this and the ability of HP ¹³C MR to detect these metabolic changes, we cultured prostate tissues in an MR-compatible bioreactor under continuous perfusion. ³¹P spectra demonstrated good viability and dynamic HP ¹³C-pyruvate MR demonstrated that high-grade PCa had significantly increased lactate efflux compared to low-grade PCa and benign prostate tissue. These metabolic differences are attributed to significantly increased LDHA expression and LDH activity, as well as significantly increased monocarboxylate transporter 4 (MCT4) expression in high- versus low- grade PCa. Moreover, lactate efflux, LDH activity, and MCT4 expression were not different between low-grade PCa and benign prostate tissues, indicating that these metabolic alterations are specific for high-grade disease. These distinctive metabolic alterations can be used to differentiate high-grade PCa from low-grade PCa and benign prostate tissues using clinically translatable HP [1-¹³C]pyruvate MR.

Current Trends in Cancer Biomarker Discovery Using Urinary Metabolomics: Achievements and New Challenges

BACKGROUND

The development of effective screening methods for early cancer detection is one of the foremost challenges facing modern cancer research. Urinary metabolomics has recently emerged as a potentially transformative approach to cancer biomarker discovery owing to its noninvasive sampling characteristics and robust analytical feasibility.

OBJECTIVE

To provide an overview of new developments in urinary metabolomics, cover the most promising aspects of hyphenated techniques in untargeted and targeted metabolomics, and to discuss technical and clinical limitations in addition to the emerging challenges in the field of urinary metabolomics and its application to cancer biomarker discovery.

METHODS

A systematic review of research conducted in the past five years on the application of urinary metabolomics to cancer biomarker discovery was performed. Given the breadth of this topic, our review focused on the five most widely studied cancers employing urinary metabolomics approaches, including lung, breast, bladder, prostate, and ovarian cancers.

RESULTS

As an extension of conventional metabolomics, urinary metabolomics has benefitted from recent technological developments in nuclear magnetic resonance, mass spectrometry, gas and liquid chromatography, and capillary electrophoresis that have improved urine metabolome coverage and analytical reproducibility. Extensive metabolic profiling in urine has revealed a significant number of altered metabolic pathways and putative biomarkers, including pteridines, modified nucleosides, and acylcarnitines, that have been associated with cancer development and progression.

CONCLUSION

Urinary metabolomics presents a transformative new approach toward cancer biomarker discovery with high translational capacity to early cancer screening.

Exhaled-breath Testing for Prostate Cancer Based on Volatile Organic Compound Profiling Using an Electronic Nose Device (Aeonose™): A Preliminary Report

BACKGROUND

Prostate biopsy, an invasive examination, is the gold standard for diagnosing prostate cancer (PCa). There is a need for a novel noninvasive diagnostic tool that achieves a significantly high pretest probability for PCa, reducing unnecessary biopsy numbers. Recent studies have shown that volatile organic compounds (VOCs) in exhaled breath can be used to detect different types of cancers via training of an artificial neural network (ANN).

OBJECTIVE

To determine whether exhaled-breath analysis using a handheld electronic nose device can be used to discriminate between VOC patterns between PCa patients and healthy individuals.

DESIGN, SETTING, AND PARTICIPANTS

This prospective pilot study was conducted in the outpatient urology clinic of the Maastricht University Medical Center, the Netherlands. Patients with histologically proven PCa were already included before initial biopsy or during follow-up, with no prior treatment for their PCa. Urological patients with negative biopsies in the past year or patients with prostate enlargement (PE) with low or stable serum prostate-specific antigen were used as controls. Exhaled breath was probed from 85 patients: 32 with PCa and 53 controls (30 having negative biopsies and 23 PE).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Patient characteristics were statistically analyzed using independent sample t test and Pearson's chi-square test. Data analysis was performed by Aethena software after data compression using the TUCKER3 algorithm. ANN models were trained and evaluated using the leave-10%-out cross-validation method.

RESULTS AND LIMITATIONS

Our trained ANN showed an accuracy of 0.75, with an area under the curve of 0.79 with sensitivity and specificity of 0.84 (95% confidence interval [CI] 0.66-0.94) and 0.70 (95% CI 0.55-0.81) respectively, comparing PCa with control individuals. The negative predictive value was found to be 0.88. The main limitation is the relatively small sample size.

CONCLUSIONS

Our findings imply that the Aeonose allows us to discriminate between patients with untreated, histologically proven primary PCa and control patients based on exhaled-breath analysis.

PATIENT SUMMARY

We explored the possibility of exhaled-breath analysis using an electronic nose, to be used as a noninvasive tool in clinical practice, as a pretest for diagnosing prostate cancer. We found that the electronic nose was able to discriminate between prostate cancer patients and control individuals.

Diagnosis and treatment for clinically localized prostate cancer. Adherence to the European Association of Urology clinical guidelines in a nationwide population-based study - GESCAP group

OBJECTIVE

To assess the adherence to European Association of Urology (EAU) guidelines in the management of prostate cancer (PCa) in Spain.

PATIENTS AND METHODS

Epidemiological, population-based, study including a national representative sample of 3,918 incident patients with histopathological confirmation during 2010; 95% of the patient's sample was followed up for at least one year. Diagnosis along with treatment related variables (for localized PCa -low, intermediate, high and locally-advanced by D'Amico risk stratification) was recorded. Differences between groups were tested with Chi-squared and Kruskal-Wallis tests.

RESULTS

Mean (SD) age of PCa patients was 68.48 (8.18). Regarding diagnostic by biopsy procedures, 64.56% of all patients had 8-12 cores in first biopsy and 46.5% of the patients over 75 years, with PSA<10ng/mL were biopsied. Staging by Computer Tomography (CT) or Bone Scan (BS) was used for determining tumor extension in 60.09% of high-risk cases and was applied differentially depending on patients' age; 3,293 (84.05%) patients received a treatment for localized PCa. Radical prostatectomy was done in 1,277 patients and 206 out of these patients also had a lymphadenectomy, being 4.64% low-risk, 22.81% intermediate-risk and 36.00% high-risk patients; 86.08% of 1,082 patients who had radiotherapy were treated with 3D or IMRT and 35.77% received a dose ≥75Gy; 419 patients were treated with brachytherapy (BT): 54.81% were low-risk patients, 22.84% intermediate-risk and 12.98% high-risk. Hormonotherapy (HT, n=521) was applied as single therapy in 9.46% of low-risk and 17.92% of intermediate-risk patients. Additionally, HT was combined with RT in 14.34% of lower-risk patients and 58.26% of high-risk patients, and 67.19% low-intermediate risk with RT and/or BT received neoadjuvant/concomitant/adjuvant HT. Finally, 83.75% of high-risk patients undergoing RT and/or BT also received HT.

CONCLUSIONS

Although EAU guidelines for PCa management are easily available in Europe, the adherence to their recommendations is low, finding the highest discrepancies in the need for a prostate biopsy and the diagnostic methods. Improve information and educational programs could allow a higher adherence to the guidelines and reduce the variability in daily practice. (Controlled-trials.com: ISRCTN19893319).

Endosomal gene expression: a new indicator for prostate cancer patient prognosis?

Prostate cancer continues to be a major cause of morbidity and mortality in men, but a method for accurate prognosis in these patients is yet to be developed. The recent discovery of altered endosomal biogenesis in prostate cancer has identified a fundamental change in the cell biology of this cancer, which holds great promise for the identification of novel biomarkers that can predict disease outcomes. Here we have identified significantly altered expression of endosomal genes in prostate cancer compared to non-malignant tissue in mRNA microarrays and confirmed these findings by qRT-PCR on fresh-frozen tissue. Importantly, we identified endosomal gene expression patterns that were predictive of patient outcomes. Two endosomal tri-gene signatures were identified from a previously published microarray cohort and had a significant capacity to stratify patient outcomes. The expression of APPL1, RAB5A, EEA1, PDCD6IP, NOX4 and SORT1 were altered in malignant patient tissue, when compared to indolent and normal prostate tissue. These findings support the initiation of a case-control study using larger cohorts of prostate tissue, with documented patient outcomes, to determine if different combinations of these new biomarkers can accurately predict disease status and clinical progression in prostate cancer patients.

Inhibition of circulating dipeptidyl peptidase 4 activity in patients with metastatic prostate cancer

Cancer is responsible for many deaths and is a major source of healthcare expenditures. The identification of new, non-invasive biomarkers might allow improvement of the direct diagnostic or prognostic ability of already available tools. Here, we took the innovative approach of interrogating the activity of exopeptidases in the serum of cancer patients with the aim of establishing a distinction based on enzymatic function, instead of simple protein levels, as a means to biomarker discovery. We first analyzed two well-characterized mouse models of prostate cancer, each with a distinct genetic lesion, and established that broad exopeptidase and targeted aminopeptidase activity tests reveal proteolytic changes associated with tumor development. We also describe new peptide-based freeze-frame reagents uniquely suited to probe the altered balance of selected aminopeptidases, as opposed to the full array of exopeptidases, and/or their modulators in patient serum or plasma. One particular proteolytic activity was impaired in animals with aggressive disease relative to cancer-free littermates. We identified the protease in question as dipeptidyl peptidase 4 (DPP4) by analyzing selected knockout mice and evaluating the effect of specific inhibitors. DPP4 activity was also reduced in the sera of patients with metastatic prostate cancer relative to patients with localized disease or healthy controls. However, no significant differences in DPP4 serum levels were observed, which established the loss of activity as the result of impaired enzymatic function. Biochemical analysis indicated that reduced activity was the result not of post-translational modifications or allosteric changes, but instead of a low-molecular-weight inhibitor. After we adjusted for age and total prostate-specific antigen, reduced DPP4 activity remained a significant predictor of cancer status. The results of this proof-of-principle study suggest that DPP4 activity might be a potential blood-based indicator of the presence of metastatic cancer of prostatic origin, either by itself or, more likely, as a means to improve the sensitivity and specificity of existing markers.

The human volatilome: volatile organic compounds (VOCs) in exhaled breath, skin emanations, urine, feces and saliva

Breath analysis is a young field of research with its roots in antiquity. Antoine Lavoisier discovered carbon dioxide in exhaled breath during the period 1777-1783, Wilhelm (Vilém) Petters discovered acetone in breath in 1857 and Johannes Müller reported the first quantitative measurements of acetone in 1898. A recent review reported 1765 volatile compounds appearing in exhaled breath, skin emanations, urine, saliva, human breast milk, blood and feces. For a large number of compounds, real-time analysis of exhaled breath or skin emanations has been performed, e.g., during exertion of effort on a stationary bicycle or during sleep. Volatile compounds in exhaled breath, which record historical exposure, are called the 'exposome'. Changes in biogenic volatile organic compound concentrations can be used to mirror metabolic or (patho)physiological processes in the whole body or blood concentrations of drugs (e.g. propofol) in clinical settings-even during artificial ventilation or during surgery. Also compounds released by bacterial strains like Pseudomonas aeruginosa or Streptococcus pneumonia could be very interesting. Methyl methacrylate (CAS 80-62-6), for example, was observed in the headspace of Streptococcus pneumonia in concentrations up to 1420 ppb. Fecal volatiles have been implicated in differentiating certain infectious bowel diseases such as Clostridium difficile, Campylobacter, Salmonella and Cholera. They have also been used to differentiate other non-infectious conditions such as irritable bowel syndrome and inflammatory bowel disease. In addition, alterations in urine volatiles have been used to detect urinary tract infections, bladder, prostate and other cancers. Peroxidation of lipids and other biomolecules by reactive oxygen species produce volatile compounds like ethane and 1-pentane. Noninvasive detection and therapeutic monitoring of oxidative stress would be highly desirable in autoimmunological, neurological, inflammatory diseases and cancer, but also during surgery and in intensive care units. The investigation of cell cultures opens up new possibilities for elucidation of the biochemical background of volatile compounds. In future studies, combined investigations of a particular compound with regard to human matrices such as breath, urine, saliva and cell culture investigations will lead to novel scientific progress in the field.

Predictions for the future of kallikrein-related peptidases in molecular diagnostics

Kallikrein-related peptidases (KLKs) form a cancer-related ensemble of serine proteases. This multigene family hosts the most widely used cancer biomarker that is PSA-KLK3, with millions of tests performed annually worldwide. The present report provides an overview of the biomarker potential of the extended KLK family (KLK1-KLK15) in various disease settings and envisages approaches that could lead to additional KLK-driven applications in future molecular diagnostics. Particular focus is given on the inclusion of KLKs into multifaceted cancer biomarker panels that provide enhanced diagnostic, prognostic and/or predictive accuracy in several human malignancies. Such panels have been described so far for prostate, ovarian, lung and colorectal cancers. The role of KLKs as biomarkers in non-malignant disease settings, such as Alzheimer's disease and multiple sclerosis, is also commented upon. Predictions are given on the challenges and future directions regarding clinically oriented KLK research.

The role of gene regulatory networks in promoting cancer progression and metastasis

ABSTRACT: 

The majority of deaths owing to cancer are ultimately caused by metastatic disease. However, most research, to date, has focused on the molecular features of cancers at their primary sites rather than on understanding disseminated malignancy in its systemic form. The dynamic nature of metastatic malignancy and its behavior as a co-ordinated systemic disease require a cancer progression paradigm that is integrative and can incorporate both the proximate causes of cancer and the broader ultimate causes in an evolutionary and developmental context. The study of robust cellular attractor states that arise directly from the architectural patterns contained within gene regulatory networks is proposed as a conceptual framework through which many of the other disparate models of cancer metastasis can be more clearly viewed and, ultimately, unified, thus providing a new conceptual framework in which to understand cancer progression and metastasis.

Fine-mapping the HOXB region detects common variants tagging a rare coding allele: evidence for synthetic association in prostate cancer

The HOXB13 gene has been implicated in prostate cancer (PrCa) susceptibility. We performed a high resolution fine-mapping analysis to comprehensively evaluate the association between common genetic variation across the HOXB genetic locus at 17q21 and PrCa risk. This involved genotyping 700 SNPs using a custom Illumina iSelect array (iCOGS) followed by imputation of 3195 SNPs in 20,440 PrCa cases and 21,469 controls in The PRACTICAL consortium. We identified a cluster of highly correlated common variants situated within or closely upstream of HOXB13 that were significantly associated with PrCa risk, described by rs117576373 (OR 1.30, P = 2.62×10(-14)). Additional genotyping, conditional regression and haplotype analyses indicated that the newly identified common variants tag a rare, partially correlated coding variant in the HOXB13 gene (G84E, rs138213197), which has been identified recently as a moderate penetrance PrCa susceptibility allele. The potential for GWAS associations detected through common SNPs to be driven by rare causal variants with higher relative risks has long been proposed; however, to our knowledge this is the first experimental evidence for this phenomenon of synthetic association contributing to cancer susceptibility.

Pre-screening age African-American males: what do they know about prostate cancer screening, knowledge, and risk perceptions?

Prostate cancer is the most commonly diagnosed cancer among men and the second most common cause of cancer mortality among men in America. African-American men have a mortality rate from prostate cancer twice that of Caucasian men. Although prostate screening remains controversial, it provides an opportunity for the cancer to be detected early when treatment is most effective. Limited research has been conducted regarding prostate cancer awareness and knowledge among African-American men under 50. This article highlights a pilot study assessing the knowledge, attitudes, risk perceptions, and reasons for participating in prostate cancer screening among African-American males between the ages of 30-45. Study findings suggest these participants recognized an awareness of risk factors associated with the disease, yet underestimated their risk of developing the disease. Additionally they present uneven knowledge of the prostate and its function and possess positive perceptions of their general health beliefs and practices. Practice implications and directions for future research regarding prostate cancer among this population are highlighted.

Identification of a novel proteoform of prostate specific antigen (SNP-L132I) in clinical samples by multiple reaction monitoring

Prostate specific antigen (PSA) is a well-established tumor marker that is frequently employed as model biomarker in the development and evaluation of emerging quantitative proteomics techniques, partially as a result of wide access to commercialized immunoassays serving as "gold standards." We designed a multiple reaction monitoring (MRM) assay to detect PSA proteoforms in clinical samples (n = 72), utilizing the specificity and sensitivity of the method. We report, for the first time, a PSA proteoform coded by SNP-L132I (rs2003783) that was observed in nine samples in both heterozygous (n = 7) and homozygous (n = 2) expression profiles. Other isoforms of PSA, derived from protein databases, were not identified by four unique proteotypic tryptic peptides. We have also utilized our MRM assay for precise quantitative analysis of PSA concentrations in both seminal and blood plasma samples. The analytical performance was evaluated, and close agreement was noted between quantitations based on three selected peptides (LSEPAELTDAVK, IVGGWECEK, and SVILLGR) and a routinely used commercialized immunoassay. Additionally, we disclose that the peptide IVGGWECEK is shared with kallikrein-related peptidase 2 and therefore is not unique for PSA. Thus, we propose the use of another tryptic sequence (SVILLGR) for accurate MRM quantification of PSA in clinical samples.

Navigating veterans with an abnormal prostate cancer screening test: a quasi-experimental study

Background

Prostate cancer disproportionately affects low-income and minority men. This study evaluates the impact of a patient navigation intervention on timeliness of diagnostic resolution and treatment initiation among veterans with an abnormal prostate cancer screen.

Methods

Participants were enrolled between 2006 and 2010. The intervention involved a social worker and lay health worker navigation team that assisted patients in overcoming barriers to care. For navigated (n = 245) versus control (n = 245) participants, we evaluated rates of diagnostic resolution and treatment and adjusted for race, age, and Gleason score.

Results

Of 490 participants, 68% were African American, 47% were ≥ 65 years old, and 35% had cancer. Among those with an abnormal screen, navigation did not have a significant effect on time to diagnostic resolution compared to controls (median days of 97 versus 111; adj. HR 1.17, 95% CI, 0.96-1.43, p = 0.12). On analysis of the period beyond 80 days, navigated men reached resolution faster than controls (median of 151 days versus 190 days; adj. HR 1.41, 95% CI, 1.07-1.86, p = 0.01). Among those with cancer, navigation did not have a significant effect on time to treatment initiation compared to controls (median of 93 days versus 87 days; adj. HR 1.15, 95% CI, 0.82-1.62, p = 0.41).

Conclusion

Our navigation program did not significantly impact the overall time to resolution or treatment for men with prostate cancer compared to controls. The utility of navigation programs may extend beyond targeted navigation times, however, and future studies focusing on other outcomes measures are therefore needed.

Baseline prostate-specific antigen measurements and subsequent prostate cancer risk in the Danish Diet, Cancer and Health cohort

AIM

Although prostate-specific antigen (PSA) screening reduces mortality from prostate cancer, substantial over-diagnosis and subsequent overtreatment are concerns. Early screening of men for PSA may serve to stratify the male population by risk of future clinical prostate cancer.

METHODS AND MATERIAL

Case-control study nested within the Danish 'Diet, Cancer and Health' cohort of 27,179 men aged 50-64 at enrolment. PSA measured in serum collected at cohort entry in 1993-1997 was used to evaluate prostate cancer risk diagnosed up to 14 years after. We identified 911 prostate cancer cases in the Danish Cancer Registry through 31st December 2007 1:1 age-matched with cancer-free controls. Aggressive cancer was defined as ≥ T3 or Gleason score ≥ 7 or N1 or M1. Statistical analyses were based on conditional logistic regression with age as underlying time axis.

RESULTS

Total PSA and free-to-total PSA ratio at baseline were strongly associated with prostate cancer risk up to 14 years later. PSA was grouped in quintiles and free-to-total PSA ratio divided in three risk groups. The incidence rate ratio for prostate cancer was 150 (95% confidence interval, 72-310) among men with a total PSA in the highest quintile (> 5.1 ng/ml) compared to the lowest (< 0.80 ng/ml). The risk of aggressive cancer was highly elevated in men with a PSA level in the highest quintile. The results indicate that one-time measurement of PSA could be used in an individualised screening strategy, sparing a large proportion of men from further PSA-based screening.

Bridging the gap between biologic, individual, and macroenvironmental factors in cancer: a multilevel approach

To address the complex nature of cancer occurrence and outcomes, approaches have been developed to simultaneously assess the role of two or more etiologic agents within hierarchical levels including the: (i) macroenvironment level (e.g., health care policy, neighborhood, or family structure); (ii) individual level (e.g., behaviors, carcinogenic exposures, socioeconomic factors, and psychologic responses); and (iii) biologic level (e.g., cellular biomarkers and inherited susceptibility variants). Prior multilevel approaches tend to focus on social and environmental hypotheses, and are thus limited in their ability to integrate biologic factors into a multilevel framework. This limited integration may be related to the limited translation of research findings into the clinic. We propose a "Multi-level Biologic and Social Integrative Construct" (MBASIC) to integrate macroenvironment and individual factors with biology. The goal of this framework is to help researchers identify relationships among factors that may be involved in the multifactorial, complex nature of cancer etiology, to aid in appropriate study design, to guide the development of statistical or mechanistic models to study these relationships, and to position the results of these studies for improved intervention, translation, and implementation. MBASIC allows researchers from diverse fields to develop hypotheses of interest under a common conceptual framework, to guide transdisciplinary collaborations, and to optimize the value of multilevel studies for clinical and public health activities.

Methylation of the RARB gene increases prostate cancer risk in black Americans

PURPOSE

Gene promoter hypermethylation may be useful as a biomarker for cancer risk in histopathologically benign prostate specimens.

MATERIALS AND METHODS

We performed a nested case-control study of gene promoter methylation status for 5 genes (APC, RARB, CCND2, RASSF1 and MGMT) measured in benign biopsy specimens from 511 prostate cancer case-control pairs. We estimated the overall and race stratified risk of subsequent prostate cancer associated with methylation status.

RESULTS

On race stratified analysis RARB methylation was associated with a higher cancer risk in black American men (OR 2.18, 95% CI 1.39-3.44). APC methylation was associated with an increased risk of high grade tumors (OR 2.43, 95% CI 1.20-4.90), which was higher in black than in white men (OR 3.21 vs 2.04). In cases RARB and APC gene methylation in benign prostate samples persisted in matched malignant specimens. In black cases the combined risk associated with RARB and APC methylation (OR 3.04, 95% CI 1.44-6.42) was greater than the individual risk of each gene and significantly different from that in white cases (OR 1.14, 95% CI 0.56-2.30).

CONCLUSIONS

RARB gene methylation in histopathologically benign prostate samples was associated with a statistically significant increased risk of subsequent prostate cancer in black men. Methylation data on additional genes may improve risk stratification and clinical decision making algorithms for cancer screening and diagnosis.

Predictors of health-related quality of life and adjustment to prostate cancer during active surveillance

BACKGROUND

Active surveillance (AS) is emerging as an alternative approach to limit the risk of overtreatment and impairment of quality of life (QoL) in patients with low-risk localised prostate cancer. Although most patients report high levels of QoL, some men may be distressed by the idea of living with untreated cancer.

OBJECTIVE

To identify factors associated with poor QoL during AS.

DESIGN, SETTING, AND PARTICIPANTS

Between September 2007 and March 2012, 103 patients participated in the Prostate Cancer Research International Active Surveillance (PRIAS) QoL study. Mental health (Symptom Checklist-90), demographic, clinical, and decisional data were assessed at entrance in AS. Health-related QoL (HRQoL) Functional Assessment of Cancer Therapy-Prostate version and Mini-Mental Adjustment to Cancer outcomes were assessed after 10 mo of AS.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Multivariate logistic regression models were used to identify predictors of low (<25th percentile) HRQoL, adjustment to cancer, and a global QoL index at 10 mo after enrollment.

RESULTS AND LIMITATIONS

The mean age of the study patients was 67 yr (standard deviation: ±7 yr). Lack of partner (odds ratio [OR]: 0.08; p=0.009) and impaired mental health (OR: 1.2, p=0.1) were associated with low HRQoL (p=0.006; area under the curve [AUC]: 0.72). The maladaptive adjustment to cancer (p=0.047; AUC: 0.60) could be predicted by recent diagnosis (OR: 3.3; p=0.072). Poor global QoL (overall p=0.02; AUC: 0.85) was predicted by impaired mental health (OR: 1.16; p=0.070) and time from diagnosis to enrollment in AS <5 mo (OR: 5.52; p=0.009). Influence of different physicians on the choice of AS (OR: 0.17; p=0.044), presence of a partner (OR: 0.22; p=0.065), and diagnostic biopsy with >18 core specimens (OR: 0.89; p=0.029) were predictors of better QoL. Limitations of this study were the small sample size and the lack of a control group.

CONCLUSIONS

Factors predicting poor QoL were lack of a partner, impaired mental health, recent diagnosis, influence of clinicians and lower number of core samples taken at diagnostic biopsy. Educational support from physicians and emotional/social support should be promoted in some cases to prevent poor QoL.

Aberrant PSA glycosylation--a sweet predictor of prostate cancer

Prostate cancer--the most commonly diagnosed cancer in men worldwide--can have a substantial effect on quality of life, regardless of the route the cancer takes. The serum PSA assay is the current gold standard option for diagnosing prostate cancer. However, a growing body of evidence suggests that PSA screening for prostate cancer results in extensive overdiagnosis and overtreatment. It is increasingly evident that the potential harm from overdiagnosis (in terms of unnecessary biopsies) must be weighed against the benefit derived from the early detection and treatment of potentially fatal prostate cancers. Rapid screening methods have been used to analyse glycosylation patterns on glycoproteins in large cohorts of patients, enabling the identification of a new generation of disease biomarkers. Changes to the expression status of certain glycan structures are now widely thought to be common features of tumour progression. In light of this development, much research has focused on the potential role of altered PSA glycosylation patterns in discriminating between significant and insignificant prostate cancers, with the aim of developing a more reliable diagnostic tool than the current serum PSA test.

Risk stratification in prostate cancer screening

Screening for prostate cancer is a controversial topic within the field of urology. The US Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial did not demonstrate any difference in prostate-cancer-related mortality rates between men screened annually rather than on an 'opportunistic' basis. However, in the world's largest trial to date--the European Randomised Study of Screening for Prostate Cancer--screening every 2-4 years was associated with a 21% reduction in prostate-cancer-related mortality rate after 11 years. Citing the uncertain ratio between potential harm and potential benefit, the US Preventive Services Task Force recently recommended against serum PSA screening. Although this ratio has yet to be elucidated, PSA testing--and early tumour detection--is undoubtedly beneficial for some individuals. Instead of adopting a 'one size fits all' approach, physicians are likely to perform personalized risk assessment to minimize the risk of negative consequences, such as anxiety, unnecessary testing and biopsies, overdiagnosis, and overtreatment. The PSA test needs to be combined with other predictive factors or be used in a more thoughtful way to identify men at risk of symptomatic or life-threatening cancer, without overdiagnosing indolent disease. A risk-adapted approach is needed, whereby PSA testing is tailored to individual risk.