Specificity of serum prostate-specific antigen determination in the Finnish prostate cancer screening trial

Bioinformatics Prediction and Analysis of MicroRNAs and Their Targets as Biomarkers for Prostate Cancer: A Preliminary Study

Prostate cancer (PCa) is the second most common form of cancer in men around the world. Due to its heterogeneity, presentations range from aggressive lethal disease to indolent disease. There is a need to identify core biomarkers that are important for early detection and progression, allowing a more precise method for the treatment and management of Pca. We obtained metastatic prostate cancer associated microRNA array profiles from the GSE28029 dataset in the GEO database. MicroRNA target prediction was done using the databases, TargetScanHuman, miRDB and DIANA microT, six target genes (FOXC1, CDKN1A, BIRC2, CTNND1, ELK1 and LRP8) were found to be common among the three different databases. Differential expression of the target genes was performed via the GENT2 database in the GPL96 platform (HG-U133A). Results indicated all genes were downregulated. Gene Ontology (GO) was used to perform enrichment analysis. The GO enrichment analysis indicated that the downregulated genes were enriched in cellular response to gamma radiation, regulation of transcription and response to drugs as well as protein binding and receptor signaling protein activity. The study suggested that CDKN1A, FOXC1 and BIRC2 might be core genes for prostate cancer that play an important role in its diagnosis, development and progression.

Discovery of novel candidate urinary protein biomarkers for prostate cancer in a multiethnic cohort of South African patients via label-free mass spectrometry

PURPOSE

Improvement in diagnostic accuracy of prostate cancer (PCa) progression using MS-based methods to analyze biomarkers in our African, Caucasian, and Mixed Ancestry patients can advance early detection and treatment monitoring.

EXPERIMENTAL DESIGN

MS-based proteomic analysis of pooled (N = 36) and individual samples (N = 45) of PCa, benign prostatic hyperplasia, normal healthy controls, and patients with other uropathies was used to identify differences in proteomics profile. Samples were analyzed for potential biomarkers and proteome coverage in African, Caucasian, and Mixed Ancestry PCa patients.

RESULTS

A total of 1102 and 5595 protein groups and nonredundant peptides, respectively, were identified in the pooling experiments (FDR = 0.01). Twenty potential biomarkers in PCa were identified and fold differences ± 2SD were observed in 17 proteins using intensity-based absolute quantification. Analysis of 45 individual samples yielded 1545 and 9991 protein groups and nonredundant peptides, respectively. Seventy-three (73) proteins groups, including existing putative PCa biomarkers, were found to be potential biomarkers of PCa by label-free quantification and demonstrated ethnic trends within our PCa cohort.

CONCLUSION AND CLINICAL RELEVANCE

Urinary proteomics is a promising route to PCa biomarker discovery and may serve as source of ethnic-related biomarkers of PCa.

Prostate-specific antigen testing: men's responses to 2012 recommendation against screening

BACKGROUND

The U.S. Preventive Services Task Force (USPSTF) released a draft recommendation advising against prostate-specific antigen (PSA) testing in October 2011, a major shift from previous years of recommending neither for or against PSA testing due to insufficient evidence.

PURPOSE

The purpose of this study was to assess men's awareness of the new recommendation, and their responses to it.

METHODS

This study comprised a web survey of men aged 40-74 years that was conducted through GfK Custom Research, LLC's Knowledge Panel® from November 22 to December 2, 2011. Chi-square tests and logistic regression analyses were conducted to identify factors associated with disagreement with and intention to follow the recommendation. Data were analyzed in March 2012.

RESULTS

The survey sample included 1089 men without a history of prostate cancer. After reviewing the recommendation, 62% agreed with the recommendation. Age and worry about getting prostate cancer were significantly related to disagreement with the recommendation. Only 13% of respondents were intenders (they planned to follow the U.S. Preventive Services Task Force recommendation and not get a prostate-specific antigen test in the future); 54% were non-intenders (they planned to not follow the U.S. Preventive Services Task Force recommendation and get a prostate-specific antigen test in the future; and 33% were undecided. Black race, higher income, having a PSA test in the past 2 years, and being somewhat/very worried about getting prostate cancer were all positively associated with being a non-intender.

CONCLUSIONS

Study findings suggest that consumers are favorably disposed to PSA testing, despite new evidence suggesting that the harms outweigh the benefits. The new USPSTF recommendation against PSA testing in all men may be met with resistance.

Screening for prostate cancer

BACKGROUND

Any form of screening aims to reduce disease-specific and overall mortality, and to improve a person's future quality of life. Screening for prostate cancer has generated considerable debate within the medical and broader community, as demonstrated by the varying recommendations made by medical organizations and governed by national policies. To better inform individual patient decision-making and health policy decisions, we need to consider the entire body of data from randomised controlled trials (RCTs) on prostate cancer screening summarised in a systematic review. In 2006, our Cochrane review identified insufficient evidence to either support or refute the use of routine mass, selective, or opportunistic screening for prostate cancer. An update of the review in 2010 included three additional trials. Meta-analysis of the five studies included in the 2010 review concluded that screening did not significantly reduce prostate cancer-specific mortality. In the past two years, several updates to studies included in the 2010 review have been published thereby providing the rationale for this update of the 2010 systematic review.

OBJECTIVES

To determine whether screening for prostate cancer reduces prostate cancer-specific mortality or all-cause mortality and to assess its impact on quality of life and adverse events.

SEARCH METHODS

An updated search of electronic databases (PROSTATE register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, CANCERLIT, and the NHS EED) was performed, in addition to handsearching of specific journals and bibliographies, in an effort to identify both published and unpublished trials.

SELECTION CRITERIA

All RCTs of screening versus no screening for prostate cancer were eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

The original search (2006) identified 99 potentially relevant articles that were selected for full-text review. From these citations, two RCTs were identified as meeting the inclusion criteria. The search for the 2010 version of the review identified a further 106 potentially relevant articles, from which three new RCTs were included in the review. A total of 31 articles were retrieved for full-text examination based on the updated search in 2012. Updated data on three studies were included in this review. Data from the trials were independently extracted by two authors.

MAIN RESULTS

Five RCTs with a total of 341,342 participants were included in this review. All involved prostate-specific antigen (PSA) testing, with or without digital rectal examination (DRE), though the interval and threshold for further evaluation varied across trials. The age of participants ranged from 45 to 80 years and duration of follow-up from 7 to 20 years. Our meta-analysis of the five included studies indicated no statistically significant difference in prostate cancer-specific mortality between men randomised to the screening and control groups (risk ratio (RR) 1.00, 95% confidence interval (CI) 0.86 to 1.17). The methodological quality of three of the studies was assessed as posing a high risk of bias. The European Randomized Study of Screening for Prostate Cancer (ERSPC) and the US Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial were assessed as posing a low risk of bias, but provided contradicting results. The ERSPC study reported a significant reduction in prostate cancer-specific mortality (RR 0.84, 95% CI 0.73 to 0.95), whilst the PLCO study concluded no significant benefit (RR 1.15, 95% CI 0.86 to 1.54). The ERSPC was the only study of the five included in this review that reported a significant reduction in prostate cancer-specific mortality, in a pre-specified subgroup of men aged 55 to 69 years of age. Sensitivity analysis for overall risk of bias indicated no significant difference in prostate cancer-specific mortality when referring to the meta analysis of only the ERSPC and PLCO trial data (RR 0.96, 95% CI 0.70 to 1.30). Subgroup analyses indicated that prostate cancer-specific mortality was not affected by the age at which participants were screened. Meta-analysis of four studies investigating all-cause mortality did not determine any significant differences between men randomised to screening or control (RR 1.00, 95% CI 0.96 to 1.03). A diagnosis of prostate cancer was significantly greater in men randomised to screening compared to those randomised to control (RR 1.30, 95% CI 1.02 to 1.65). Localised prostate cancer was more commonly diagnosed in men randomised to screening (RR 1.79, 95% CI 1.19 to 2.70), whilst the proportion of men diagnosed with advanced prostate cancer was significantly lower in the screening group compared to the men serving as controls (RR 0.80, 95% CI 0.73 to 0.87). Screening resulted in a range of harms that can be considered minor to major in severity and duration. Common minor harms from screening include bleeding, bruising and short-term anxiety. Common major harms include overdiagnosis and overtreatment, including infection, blood loss requiring transfusion, pneumonia, erectile dysfunction, and incontinence. Harms of screening included false-positive results for the PSA test and overdiagnosis (up to 50% in the ERSPC study). Adverse events associated with transrectal ultrasound (TRUS)-guided biopsies included infection, bleeding and pain. No deaths were attributed to any biopsy procedure. None of the studies provided detailed assessment of the effect of screening on quality of life or provided a comprehensive assessment of resource utilization associated with screening (although preliminary analyses were reported).

AUTHORS' CONCLUSIONS

Prostate cancer screening did not significantly decrease prostate cancer-specific mortality in a combined meta-analysis of five RCTs. Only one study (ERSPC) reported a 21% significant reduction of prostate cancer-specific mortality in a pre-specified subgroup of men aged 55 to 69 years. Pooled data currently demonstrates no significant reduction in prostate cancer-specific and overall mortality. Harms associated with PSA-based screening and subsequent diagnostic evaluations are frequent, and moderate in severity. Overdiagnosis and overtreatment are common and are associated with treatment-related harms. Men should be informed of this and the demonstrated adverse effects when they are deciding whether or not to undertake screening for prostate cancer. Any reduction in prostate cancer-specific mortality may take up to 10 years to accrue; therefore, men who have a life expectancy less than 10 to 15 years should be informed that screening for prostate cancer is unlikely to be beneficial. No studies examined the independent role of screening by DRE.

Clinical and pathological characteristics of screen-detected versus clinically diagnosed prostate cancer in Nanjing, China

Previous studies have suggested that implementation of PSA screening in China is of crucial importance. This study compared clinical and pathological characteristics of screen-detected and clinically diagnosed prostate cancers and evaluated the effectiveness of PSA screening for early detection of prostate cancer in Nanjing. Between July 2004 and December 2005, 8,562 men aged ≥ 50 years were included for PSA screening. Participants with serum PSA ≥ 4.0 ng/ml were recommended for transrectal ultrasonography (TRUS)-guided prostate needle biopsy (TRNB). During the same period, 82 consecutive clinically diagnosed prostate cancers were included as controls. The clinical and pathological features of the screened versus clinically diagnosed cancers were evaluated. A total of 719 (8.4%) of screened men had PSA levels ≥ 4.0 ng/ml. Biopsy was performed in 295 men, and 58 prostate cancers were detected. The biopsy rate, positive predictive value (PPV), and detection rate were 41.0, 19.7, and 0.68%, respectively. More screened patients were found with PSA levels <20 ng/ml (55.2 vs. 22.4%, P < 0.001), Gleason scores <7 (60.3 vs. 34.1%, P = 0.002), organ-confined tumors (87.9 vs. 26.8%, P < 0.001), and opportunities for radical prostatectomy (50.0 vs. 18.3%, P < 0.001) than that in clinically diagnosed patients. PSA screening is effective for early detection of prostate cancer in Chinese elderly men. Favorable PSA levels, Gleason scores, clinical stages, and chances for radical prostatectomy are associated with PSA screening. Further studies are needed to evaluate the effect of screening on treatment outcomes and mortality of prostate cancer in Chinese.

False-positive screening results in the Finnish prostate cancer screening trial

BACKGROUND

There is evidence that prostate cancer (PC) screening with prostate-specific antigen (PSA) serum test decreases PC mortality, but screening has adverse effects, such as a high false-positive (FP) rate. We investigated the proportion of FPs in a population-based randomised screening trial in Finland.

METHODS

Finland is the largest centre in the European Randomized Study of Screening for Prostate Cancer. We have completed three screening rounds with a 4-year screening interval (mean follow-up time 9.2 years) using a PSA cutoff level of 4.0 ng ml(-1); in addition, men with PSA 3.0-3.9 and a positive auxiliary test were referred. An FP result was defined as a positive screening result without cancer in biopsy within 1 year from the screening test.

RESULTS

The proportion of FP screening results varied from 3.3 to 12.1% per round. Of the screened men, 12.5% had at least one FP during three rounds. The risk of next-round PC following an FP result was 12.3-19.7 vs 1.4-3.7% following a screen-negative result (depending on the screening round), risk ratio 3.6-9.9. More than half of the men with one FP result had another one at a subsequent screen. Men with an FP result were 1.5 to 2.0 times more likely to not participate in subsequent rounds compared with men with a normal screening result (21.6-29.6 vs 14.0-16.7%).

CONCLUSION

An FP result is a common adverse effect of PC screening and affects at least every eighth man screened repeatedly, even when using a relatively high cutoff level. False-positive men constitute a special group that receives unnecessary interventions but may harbour missed cancers. New strategies are needed for risk stratification in PC screening to minimise the proportion of FP men.

Prostate specific antigen for early detection of prostate cancer: longitudinal study

OBJECTIVE

To evaluate if prostate specific antigen test attains validity standards required for screening in view of recent prostate cancer screening trial results.

DESIGN

Case-control study nested in longitudinal cohort.

SETTING

Västerbotten Intervention Project cohort, Umeå, Sweden.

PARTICIPANTS

540 cases and 1034 controls matched for age and date of blood draw.

MAIN OUTCOME MEASURE

Validity of prostate specific antigen for prediction of subsequent prostate cancer diagnosis by record linkage to cancer registry.

RESULTS

Blood samples were drawn on average 7.1 (SD 3.7) years before diagnosis. The area under the curve for prostate specific antigen was 0.84 (95% confidence interval 0.82 to 0.86). At prostate specific antigen cut-off values of 3, 4, and 5 ng/ml, sensitivity estimates were 59%, 44%, and 33%, and specificity estimates were 87%, 92%, and 95%. The positive likelihood ratio commonly considered to "rule in disease" is 10; in this study the positive likelihood ratios were 4.5, 5.5, and 6.4 for prostate specific antigen cut-off values of 3, 4, and 5 ng/ml. The negative likelihood ratio commonly considered to "rule out disease" is 0.1; in this study the negative likelihood ratios were 0.47, 0.61, and 0.70 for prostate specific antigen cut-off values of 3, 4, and 5 ng/ml. For a cut-off of 1.0 ng/ml, the negative likelihood ratio was 0.08.

CONCLUSIONS

No single cut-off value for prostate specific antigen concentration attained likelihood ratios formally required for a screening test. Prostate specific antigen concentrations below 1.0 ng/ml virtually ruled out a prostate cancer diagnosis during the follow-up. Additional biomarkers for early detection of prostate cancer are needed before population based screening for prostate cancer should be introduced.

Small integrin-binding proteins as serum markers for prostate cancer detection

PURPOSE

The small integrin-binding ligand N-linked glycoprotein (SIBLING) gene family includes bone sialoprotein (BSP), dentin matrix protein 1 (DMP1), dentin sialophosphoprotein (DSPP), matrix extracellular phosphoglycoprotein (MEPE), and osteopontin (OPN). Previous studies have separately reported elevated expression of BSP, OPN, or DSPP in prostate tumor paraffin sections. We hypothesized that SIBLINGs may be informative serum markers for subjects with prostate cancer.

METHODS

Expression levels of SIBLINGs in biopsies of normal tissue and tumors from prostate were determined by cDNA array and by immunohistochemical staining with monoclonal antibodies. Competitive ELISAs for measuring total BSP, DSPP, MEPE, and OPN were applied to a test group of 102 subjects with prostate cancer and 110 normal subjects and a validation group of 90 subjects.

RESULTS

BSP, DMP1, DSPP, and OPN exhibited elevated mRNA expression and protein levels in biopsies. BSP, DSPP, and OPN were elevated in serum from prostate cancer subjects, with serum DSPP exhibiting the greatest difference, yielding an area under the receiver operator characteristic curve value of 0.98. Serum BSP and OPN levels were significantly elevated only in late stages, whereas DSPP was significantly elevated at all stages. Optimal serum value cutoff points derived for BSP, OPN, and DSPP were applied as a validation test to a new group of 90 subjects and DSPP yielded a sensitivity of 90% and a specificity of 100%.

CONCLUSION

Of the SIBLING gene family members, DSPP appears to be a strong candidate for use in serum assays for prostate cancer detection.

Early prostate-specific antigen changes and the diagnosis and prognosis of prostate cancer

PURPOSE OF REVIEW

To delineate how recent findings on prostate-specific antigen (PSA) can improve prediction of risk, detection, and prediction of clinical endpoints of prostate cancer (PCa).

RECENT FINDINGS

The widely used PSA cut-point of 4.0 ng/ml increasingly appears arbitrary, but no cut-point achieves both high sensitivity and high specificity. The accuracy of detecting PCa can be increased by additional predictive factors and a combinations of markers. Evidence implies that a panel of kallikrein markers improves the specificity and reduces costs by eliminating unnecessary biopsies. Large, population-based studies have provided evidence that PSA can be used to predict PCa risk many years in advance, improve treatment selection and patient care, and predict the risk of complications and disease recurrence. However, definitive evidence is currently lacking as to whether PSA screening lowers PCa -specific mortality.

SUMMARY

PSA is still the main tool for early detection, risk stratification, and monitoring of PCa. However, PSA values are affected by many technical and biological factors. Instead of using a fixed PSA cut-point, using statistical prediction models and considering the integration additional markers may be able to improve and individualize PCa diagnostics. A single PSA measurement at early middle age can predict risk of advanced PCa decades in advance and stratify patients for intensity of subsequent screening.

Test sensitivity in the European prostate cancer screening trial: results from Finland, Sweden, and the Netherlands

Test sensitivity pertains to the ability of a test to identify subjects with the target disorder. In cancer screening, test sensitivity can be estimated using interval cancer incidence as an indicator of false-negative result. A randomized trial provides the optimal approach for estimating test sensitivity, as the control arm provides the expected rates. We estimated the sensitivity of the prostate-specific antigen test using incidence method, i.e., based on incidence of interval cancer among subjects with negative screening results, compared with that in the control arm. Data from three centers in the European randomized screening trial were used to estimate interval cancer incidence (I(I)) among 39,389 men with negative screening tests. This was compared with incidence among the 79,525 men in the control arm of the trial (I(c)) to estimate test sensitivity (S = 1 - I(I) / I(C)). Confidence intervals were calculated using simulations, assuming that the number of cases follows a Poisson distribution. The estimated test sensitivity following the first screen was 0.87 (0.83-0.92) in Finland, 0.87 (0.62-1.00) in Sweden, and 0.93 (95% confidence interval, 0.90-0.96) in the Netherlands. There was some indication of a higher test sensitivity for aggressive cancers (0.85-0.98 for non-organ-confined cases or Gleason 8-10) and for the second screening round (approximately 0.85-0.95). Test sensitivity varied to some extent between the three centers in the European trial, probably reflecting variation in screening protocols, but was acceptable in the first screening round, and may be better for aggressive cancers and in the second screening round.

Screening for prostate cancer

BACKGROUND

Any form of screening aims to reduce mortality and increase a person's quality of life. Screening for prostate cancer has generated considerable debate within the medical community, as demonstrated by the varying recommendations made by medical organizations and governed by national policies. Much of this debate is due to the limited availability of high quality research and the influence of false-positive or false-negative results generated by use of the diagnostic techniques such as the digital rectal examination (DRE) and prostate specific antigen (PSA) blood test.

OBJECTIVES

To determine whether screening for prostate cancer reduces prostate cancer mortality and has an impact on quality of life.

SEARCH STRATEGY

Electronic databases (PROSTATE register, CENTRAL the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, CANCERLIT and the NHS EED) were searched electronically in addition to hand searching of specific journals and bibliographies in an effort to identify both published and unpublished trials.

SELECTION CRITERIA

All randomised controlled trials of screening versus no screening or routine care for prostate cancer were eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

The search identified 99 potentially relevant articles that were selected for full text review. From these 99 citations, two randomised controlled trials were identified as meeting the review's inclusion criteria. Data from the trials were independently extracted by two authors.

MAIN RESULTS

Two randomised controlled trials with a total of 55,512 participants were included; however, both trials had methodological weaknesses. Re-analysis using intention-to-screen and meta-analysis of results from the two randomised controlled trials indicated no statistically significant difference in prostate cancer mortality between men randomised for prostate cancer screening and controls (RR 1.01, 95% CI: 0.80-1.29). Neither study assessed the effect of prostate cancer screening on quality of life, all-cause mortality or cost effectiveness.

AUTHORS' CONCLUSIONS

Given that only two randomised controlled trials were included, and the high risk of bias of both trials, there is insufficient evidence to either support or refute the routine use of mass, selective or opportunistic screening compared to no screening for reducing prostate cancer mortality. Currently, no robust evidence from randomised controlled trials is available regarding the impact of screening on quality of life, harms of screening, or its economic value. Results from two ongoing large scale multicentre randomised controlled trials that will be available in the next several years are required to make evidence-based decisions regarding prostate cancer screening.