Latest results from the UK trials evaluating prostate cancer screening and treatment: the CAP and ProtecT studies

The European Randomised Study of Screening for Prostate Cancer (ERSPC) demonstrated a significant reduction in prostate cancer-specific mortality. The ongoing Comparison Arm for ProtecT (CAP) cluster randomised controlled trial (RCT) evaluates prostate cancer screening effectiveness by comparing primary care centres allocated to a round of prostate specific antigen (PSA) testing (intervention) or standard clinical care. Over 550 centres (around 450,000 men) were randomised in eight United Kingdom areas (2002-2008). Intervention group participants were also eligible for the ProtecT (Prostate testing for cancer and Treatment) RCT evaluating active monitoring, radiotherapy and radical prostatectomy treatments for localised prostate cancer. In ProtecT, over 1500 of around 3000 men with prostate cancer were randomised from over 10,000 with an elevated PSA in around 111,000 attendees at clinics. Investigation of the psychological impact of screening in a sub-sample showed that 10% of men still experienced high distress up to 3 months following prostate biopsies (22/227), although most were relatively unaffected. The risk of prostate cancer with a raised PSA was lower if urinary symptoms were present (frequent nocturia odds ratio (OR) 0.44, 95% confidence interval (CI) 0.22-0.83) or if a repeat PSA decreased by > or = 20% prior to biopsy (OR 0.43, 95% CI 0.35-0.52). Men aged 45-49 years attended PSA clinics less frequently (442/1299, 34%) in a nested cohort with a cancer detection rate of 2.3% (10/442). The CAP and ProtecT trials (ISRCTN92187251 and ISRCTN20141217) will help resolve the prostate cancer screening debate, define the optimum treatment for localised disease and generate evidence to improve men's health.

Transurethral resection biopsy as part of a saturation biopsy protocol: a cohort study and review of the literature

OBJECTIVE

To evaluate the prostate cancer (CaP) detection rate and morbidity of performing a transurethral resection biopsy of the prostate (TURBP) at the same time as a saturation biopsy (SBx).

PATIENTS

A total of 102 men with previous negative transrectal ultrasound (TRUS) biopsies underwent a SBx under formal anaesthesia. Fifty-four [54 (52.9%)] had a combined SBx and TURBP (Group 1) and 48 (47.1%) had a SBx only (Group 2).

RESULTS

The CaP detection rate in Group 1 was 38.9% (21/54), which was significantly higher than the detection rate of 27.1% (13/48) in Group 2 (P = 0.005). CaP was detected via TURBP in 12 patients (22.2%) from Group 1, including 8 (14.8%) patients who had CaP solely in their TURBP chips. According to the D'Amico classification, 66.6% (14/21) of the cancers in Group 1 were intermediate (n = 4) or high risk (n = 10). Of the 8 'TURBP only' cancers, 75% (6/8) were intermediate (n = 2) or high risk (n = 4). Seven of these eight patients went on to have a radical prostatectomy (RP) but only 2 (28.6%) were found to have a pure anterior/transition zone (TZ) tumor. The postoperative urinary retention and emergency admission rates for Groups 1 and 2 were 29.6% (16/54) vs. 16.6% (8/48) (P = 0.095) and 11.1% (6/54) vs. 5.5% (2/48) (n = 0.17). There was no difference in terms of hematuria (P = 0.54), urinary tract infection (UTI) (P = 0.22), or sepsis (P = 0.21), and patients in Group 1 spent an average of 0.5 days longer in hospital (1.9 vs. 1.4; P = 0.008).

CONCLUSIONS

TURBP in association with SBx increases the detection of clinically important CaP. However, this does have to be balanced against the small increased incidence of urinary retention, emergency re-admission, and longer hospital stay.

Prostate-specific antigen testing rates remain low in UK general practice: a cross-sectional study in six English cities

OBJECTIVE • To estimate rates of prostate-specific antigen (PSA) testing in UK general practices by age, deprivation index and geographical location. SUBJECTS AND METHODS • Practice-based, retrospective data on PSA testing patterns in 2007 were collected from a random sample of 87 general practices using EMIS LV computer systems within the passively observed non-intervention arm of a cluster-randomized controlled trial. • Information for a total of 126 716 men aged 45-89 years with no recorded diagnosis of prostate cancer prior to 1 January 2007 was collected. RESULTS • In all, 7902 (6.2%) of 126 716 men aged 45-89 without a prior diagnosis of prostate cancer underwent at least one PSA test from their general practitioner during 2007 [95% confidence interval (CI) 5.6-7.0%; practice-based inter-quartile range 3.6-8.4%]. • PSA testing rates were 1.4% (95% CI 1.1-1.6%) in men aged 45-49, rising to 11.3% (95% CI 10.0-12.9%) at age 75-79 years (P for trend <0.001). • Testing rates were lowest in the three northern centres (3.5-5.7%) vs the three more southern centres (7.1-8.9%; P < 0.001). • For every 20 points increase in the index of multiple deprivation score, the proportion of men tested fell by 1.7% (95% CI -2.5 to -0.8%; P < 0.001). • Lower proportions of men were subsequently diagnosed with prostate cancer in practices testing more men (odds ratio for a one unit increase in the natural log of testing 0.76; 95% CI 0.60-0.97; P= 0.025). CONCLUSION • Overall levels of PSA testing in UK general practice remain low, but for those tested there are important variations by age, deprivation and geographical location that do not appear to reflect clinical need or the intention of current policy. • PSA testing in general practice is currently skewed towards older men, and current policy enabling all men to make an informed choice about PSA testing is not being effectively implemented as uptake clearly varies by socioeconomic status. • This reinforces the need for robust evidence regarding the costs and benefits of using the PSA test for the detection of localized prostate cancer in the UK, a full assessment of the health economic implications and a revision of the current policy.

Label-free quantitative proteomics reveals differentially regulated proteins influencing urolithiasis

Urinary proteins have been implicated as inhibitors of kidney stone formation (urolithiasis). As a proximal fluid, prefiltered by the kidneys, urine is an attractive biofluid for proteomic analysis in urologic conditions. However, it is necessary to correct for variations in urinary concentration. In our study, individual urine samples were normalized for this variation by using a total protein to creatinine ratio. Pooled urine samples were compared in two independent experiments. Differences between the urinary proteome of stone formers and nonstone-forming controls were characterized and quantified using label-free nano-ultraperformance liquid chromatography high/low collision energy switching analysis. There were 1063 proteins identified, of which 367 were unique to the stone former groups, 408 proteins were unique to the control pools, and 288 proteins were identified for comparative quantification. Proteins found to be unique in stone-formers were involved in carbohydrate metabolism pathways and associated with disease states. Thirty-four proteins demonstrated a consistent >twofold change between stone formers and controls. For ceruloplasmin, one of the proteins was shown to be more than twofold up-regulated in the stone-former pools, this observation was validated in individuals by enzyme-linked immunosorbent assay. Moreover, in vitro crystallization assays demonstrated ceruloplasmin had a dose-dependent increase on calcium oxalate crystal formation. Taken together, these results may suggest a functional role for ceruloplasmin in urolithiasis.

Seasonal variation in prostate-specific antigen levels: a large cross-sectional study of men in the UK

OBJECTIVE

• To assess whether a seasonal change in prostate specific antigen (PSA) levels can be detected in men recruited to a large clinical trial.

PATIENTS AND METHODS

• A total of 66 969 men aged 50-69 years were drawn from a large study conducted at general practices across the UK between 2002 and 2007. • Trigonometric algorithms and regression methods were used to assess the relationship between the time of year and serum PSA and blood pressure measurements. • We obtained local daily mean temperatures and hours of sunlight per day to assess whether these factors were potential mechanisms for seasonal variation in PSA levels or blood pressure. • The proportion of participants who would be considered clinically at risk according to their PSA or blood pressure measurement, by month, was also assessed. • The strength of associations between time of year and blood pressure were used to reinforce conclusions from the PSA models.

RESULTS

• There was no relationship between time of year and PSA levels (P= 0.11) or between climate and PSA levels (P= 0.42). • No difference was found in the prevalence of clinically raised PSA content by month (P= 0.50). • This lack of an association with PSA content was despite our data being sufficient to provide clear evidence of an association between blood pressure and time of year (systolic P < 0.001; diastolic P < 0.001), and to show that this association was largely explained by climatic factors (temperature and sunlight).

CONCLUSION

• There was no pattern in PSA levels by time of year, air temperature or levels of sunlight in this cohort, so there is no need to take these factors into account when reviewing PSA results.

Genetic correction of PSA values using sequence variants associated with PSA levels

Measuring serum levels of the prostate-specific antigen (PSA) is the most common screening method for prostate cancer. However, PSA levels are affected by a number of factors apart from neoplasia. Notably, around 40% of the variability of PSA levels in the general population is accounted for by inherited factors, suggesting that it may be possible to improve both sensitivity and specificity by adjusting test results for genetic effects. To search for sequence variants that associate with PSA levels, we performed a genome-wide association study and follow-up analysis using PSA information from 15,757 Icelandic and 454 British men not diagnosed with prostate cancer. Overall, we detected a genome-wide significant association between PSA levels and single-nucleotide polymorphisms (SNPs) at six loci: 5p15.33 (rs2736098), 10q11 (rs10993994), 10q26 (rs10788160), 12q24 (rs11067228), 17q12 (rs4430796), and 19q13.33 [rs17632542 (KLK3: I179T)], each with P(combined) <3 × 10(-10). Among 3834 men who underwent a biopsy of the prostate, the 10q26, 12q24, and 19q13.33 alleles that associate with high PSA levels are associated with higher probability of a negative biopsy (odds ratio between 1.15 and 1.27). Assessment of association between the six loci and prostate cancer risk in 5325 cases and 41,417 controls from Iceland, the Netherlands, Spain, Romania, and the United States showed that the SNPs at 10q26 and 12q24 were exclusively associated with PSA levels, whereas the other four loci also were associated with prostate cancer risk. We propose that a personalized PSA cutoff value, based on genotype, should be used when deciding to perform a prostate biopsy.

Associations of aspirin, nonsteroidal anti-inflammatory drug and paracetamol use with PSA-detected prostate cancer: findings from a large, population-based, case-control study (the ProtecT study)

Evidence from laboratory studies suggests that chronic inflammation plays an important role in prostate cancer aetiology. This has resulted in speculation that nonsteroidal anti-inflammatory drugs may protect against prostate cancer development. We analysed data from a cross-sectional case-control study (n(cases) = 1,016; n(controls) = 5,043), nested within a UK-wide population-based study that used prostate specific antigen (PSA) testing for identification of asymptomatic prostate cancers, to investigate the relationship of aspirin, nonsteroidal anti-inflammatory drug (NSAID) and paracetamol use with prostate cancer. In conditional logistic regression models accounting for stratum matching on age (5-year age bands) and recruitment centre, use of non-aspirin NSAIDs [odds ratio (OR) = 1.32; 95% confidence interval (CI): 1.04-1.67] or all NSAIDs (OR = 1.25; 95% CI = 1.07-1.47) were positively associated with prostate cancer. There were weaker, not conventionally statistically significant, positive associations of aspirin (OR = 1.13; 95% CI = 0.94-1.36) and paracetamol (OR = 1.20; 95% CI = 0.90-1.60) with prostate cancer. Mutual adjustment for aspirin, non-aspirin NSAIDs or paracetamol made little difference to these results. There was no evidence of confounding by age, family history of prostate cancer, body mass index or self-reported diabetes. Aspirin, NSAID and paracetamol use were associated with reduced serum PSA concentrations amongst controls. Our findings do not support the hypothesis that NSAIDs reduce the risk of PSA-detected prostate cancer. Our conclusions are unlikely to be influenced by PSA detection bias because the inverse associations of aspirin, NSAID and paracetamol use with serum PSA would have attenuated (not generated) the observed positive associations.

MicroRNA in prostate, bladder, and kidney cancer: a systematic review

CONTEXT

MicroRNAs (miRNA) are noncoding RNAs that post-transcriptionally regulate gene expression. Their altered expression and function have been observed in most urologic cancers. MiRNAs represent potential disease biomarkers and novel therapeutic targets.

OBJECTIVE

To review and evaluate the evidence implicating miRNAs in the pathogenesis of prostate cancer (PCa), bladder cancer (BCa), and renal cancer.

EVIDENCE ACQUISITION

A systematic review was performed using PubMed and Embase to search for reports using strings for microRNA, non-coding RNA, cancer, prostate, bladder, and renal cancer. Identified manuscripts were retrieved and references searched. Selected studies were required to concentrate on the role of miRNA in these urologic cancers.

EVIDENCE SYNTHESIS

We reviewed articles that focus on this topic. More than 40 miRNAs have been implicated in urologic cancer and many target common carcinogenic pathways. In particular, apoptosis avoidance, cell proliferation, epithelial-to-mesenchymal transition, angiogenic signalling, and the generation of androgen independence are targeted or facilitated by more than one miRNA. Little work has been done to evaluate the translational applications for this knowledge to date. Novel therapeutic strategies have been developed and are under investigation to selectively modulate miRNAs; such work would potentially enable personalised tumour therapy.

CONCLUSIONS

MiRNAs appear to be important modulators of urologic cancer. Their expression is frequently altered in these tumours, and many are functionally implicated in their pathogenesis. They require evaluation to determine the translational role and therapeutic potential for this knowledge.

Association of obesity with prostate cancer: a case-control study within the population-based PSA testing phase of the ProtecT study

Background:

Obesity has been inconsistently linked to prostate cancer, mainly with mortality rather than incidence. Few large-scale studies exist assessing obesity in relation to prostate-specific antigen (PSA)-detected prostate cancer.

Methods:

We used cases and stratum-matched controls from the population-based PSA-testing phase of the Prostate testing for cancer and Treatment study to examine the hypothesis that obesity as measured by body mass index (BMI), waist circumference and waist-to-hip ratio (WHR) is associated with increased prostate cancer risk, and with higher tumour stage and grade. In all, 2167 eligible cases and 11 638 randomly selected eligible controls with PSA values were recruited between 2001 and 2008. A maximum of 960 cases and 4156 controls had measurement data, and also complete data on age and family history, and were included in the final analysis. BMI was categorised as <25.0, 25.0–29.9, ⩾30.0 in kg m⁻².

Results:

Following adjustment for age and family history of prostate cancer, we found little evidence that BMI was associated with total prostate cancer (odds ratio (OR): 0.83, 95% confidence interval (CI): 0.67, 1.03; highest vs lowest tertile; P-trend 0.1). A weak inverse association was evident for low-grade (OR: 0.76, 95% CI: 0.59, 0.97; highest vs lowest tertile; P-trend 0.045) prostate cancer. We found no association of either waist circumference (OR: 0.94, 95% CI: 0.80, 1.12; highest vs lowest tertile) or waist-to-hip ratio (WHR; OR: 0.93, 95% CI: 0.77, 1.11; highest vs lowest tertile) with total prostate cancer, and in analyses stratified by disease stage (all P-trend>0.35) or grade (all P-trend>0.16).

Conclusion:

General adiposity, as measured by BMI, was associated with a decreased risk of low-grade PSA-detected prostate cancer. However, effects were small and the confidence intervals had limits very close to one. Abdominal obesity (as measured by WHR/waist circumference) was not associated with PSA-detected prostate cancer.

A Peer Review Intervention for Monitoring and Evaluating sites (PRIME) that improved randomized controlled trial conduct and performance

OBJECTIVE

Good clinical practice (GCP) guidelines emphasize trial site monitoring, although the implementation is unspecified and evidence for benefit is sparse. We aimed to develop a site monitoring process using peer reviewers to improve staff training, site performance, data collection, and GCP compliance.

STUDY DESIGN AND SETTING

The Peer Review Intervention for Monitoring and Evaluating sites (PRIME) team observed and gave feedback on trial recruitment and follow-up appointments, held staff meetings, and examined documentation during annual 2-day site visits. The intervention was evaluated in the ProtecT trial, a UK randomized controlled trial of localized prostate cancer treatments (ISRCTN20141297). The ProtecT coordinator and senior nurses conducted three monitoring rounds at eight sites (2004-2007). The process evaluation used PRIME report findings, trial databases, resource use, and a site nurse survey.

RESULTS

Adverse findings decreased across all sites from 44 in round 1 to 19 in round 3. Most findings related to protocol adherence or site organizational issues, including improvements in eligibility criteria application and data collection. Staff found site monitoring acceptable and made changes after reviews.

CONCLUSION

The PRIME process used observation by peer reviewers to improve protocol adherence and train site staff, which increased trial performance and consistency.

Hypermethylation of CpG islands and shores around specific microRNAs and mirtrons is associated with the phenotype and presence of bladder cancer

PURPOSE

To analyze the role and translational potential for hypermethylation of CpG islands and shores in the regulation of small RNAs within urothelial cell carcinoma (UCC). To examine microRNAs (miR) and mirtrons, a new class of RNA located within gene introns and processed in a Drosha-independent manner.

EXPERIMENTAL DESIGN

The methylation status of 865 small RNAs was evaluated in normal and malignant cell lines by using 5-azacytidine and microarrays. Bisulfite sequencing was used for CpG regions around selected RNAs. Prognostic and diagnostic associations for epigenetically regulated RNAs were examined by using material from 359 patients, including 216 tumors and 121 urinary samples (68 cases and 53 controls). Functional analyses examined the effect of silencing susceptible RNAs in normal urothelial cells.

RESULTS

Exonic/UTR-located miRs and mirtons are most susceptible to epigenetic regulation. We identified 4 mirtrons and 16 miRs with CpG hypermethylation across 35 regions in normal and malignant urothelium. For several miRs, hypermethylation was more frequent and dense in CpG shores than islands (e.g., miRs-9/149/210/212/328/503/1224/1227/1229), and was associated with tumor grade, stage, and prognosis (e.g., miR-1224 multivariate analysis OR = 2.5; 95% CI, 1.3-5.0; P = 0.006). The urinary expression of epigenetically silenced RNAs (miRs-152/328/1224) was associated with the presence of UCC (concordance index, 0.86; 95% CI, 0.80-0.93; ANOVA P < 0.016).

CONCLUSIONS

Hypermethylation of mirtrons and miRs is common in UCC. Mirtrons appear particularly susceptible to epigenetic regulation. Aberrant hypermethylation of small RNAs is associated with the presence and behavior of UCC, suggesting potential roles as diagnostic and prognostic biomarkers.

Eight-plex iTRAQ analysis of variant metastatic human prostate cancer cells identifies candidate biomarkers of progression: An exploratory study

BACKGROUND

Due to the heterogeneity in the biological behavior of prostate cancer, biomarkers that can reliably distinguish indolent from aggressive disease are urgently needed to inform treatment choices.

METHODS

We employed 8-plex isobaric Tags for Relative and Absolute Quantitation (iTRAQ), to profile the proteomes of two distinct panels of isogenic prostate cancer cells with varying growth and metastatic potentials, in order to identify novel biomarkers associated with progression. The LNCaP, LNCaP-Pro5, and LNCaP-LN3 panel of cells represent a model of androgen-responsive prostate cancer, while the PC-3, PC-3M, and PC-3M-LN4 panel represent a model of androgen-insensitive disease.

RESULTS

Of the 245 unique proteins identified and quantified (>or=95% confidence; >or=2 peptides/protein), 17 showed significant differential expression (>or=+/-1.5), in at least one of the variant LNCaP cells relative to parental cells. Similarly, comparisons within the PC-3 panel identified 45 proteins to show significant differential expression in at least one of the variant PC-3 cells compared with parental cells. Differential expression of selected candidates was verified by Western blotting or immunocytochemistry, and corresponding mRNA expression was determined by quantitative real-time PCR (qRT-PCR). Immunostaining of prostate tissue microarrays for ERp5, one of the candidates identified, showed a significant higher immunoexpression in pre-malignant lesions compared with non-malignant epithelium (P < 0.0001, Mann-Whitney U-test), and in high Gleason grade (4-5) versus low grade (2-3) cancers (P < 0.05).

CONCLUSIONS

Our study provides proof of principle for the application of an 8-plex iTRAQ approach to uncover clinically relevant candidate biomarkers for prostate cancer progression.

Androgen regulates ADAMTS15 gene expression in prostate cancer cells

Prostate cancer is a major cause of mortality, largely as a consequence of metastases and transformation to androgen-independent growth. Metalloproteinases are implicated in cancer progression. A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) are expressed in prostate cancer cells, with ADAMTS-1 and ADAMTS-15 being the most abundant. ADAMTS-15 but not ADAMTS-1 expression was downregulated by androgen in LNCaP prostate cancer cells, possibly through androgen response elements associated with the gene. ADAMTS-15 expression is predictive for survival in breast cancer, and the situation may be similar in prostate cancer, as androgen independence is usually due to aberrant signaling through its receptor.

Metabolic imbalance and prostate cancer progression

There is substantial evidence implicating environmental factors in the progression of prostate cancer. The metabolic consequences of a western lifestyle, such as obesity, insulin resistance and abnormal hormone production have been linked to prostate carcinogenesis through multiple overlapping pathways. Insulin resistance results in raised levels of the mitogens insulin and insulin-like growth factor-1, both of which may affect prostate cancer directly, or through their effect on other metabolic regulators. Obesity is associated with abnormal levels of adipocyte-derived peptides (adipokines), sex hormones and inflammatory cytokines. Adipokines have been shown to influence prostate cancer in both cell culture studies and observational, population level studies. Testosterone appears to have a complex relationship with prostate carcinogenesis, and it has been suggested that the lower levels associated with obesity may select for more aggressive androgen independent prostate cancer cells. Prostatic inflammation, caused by infection, urinary reflux or dietary toxins, frequently occurs prior to cancer development and may influence progression to advanced disease. High levels of ω-6 fatty acids in the diet may lead to the production of further inflammatory molecules that may influence prostate cancer. Increased fatty acid metabolism occurs within tumour cells, providing a potential target for prostate cancer therapies. Aberrations in amino acid metabolism have also been identified in prostate cancer tissue, particularly in metastatic cancer. This evidence indicates lifestyle interventions may be effective in reducing the incidence of clinical disease. However, much more research is needed before recommendations are made.

High aldehyde dehydrogenase activity identifies tumor-initiating and metastasis-initiating cells in human prostate cancer

Metastatic progression of advanced prostate cancer is a major clinical problem. Identifying the cell(s) of origin in prostate cancer and its distant metastases may permit the development of more effective treatment and preventive therapies. In this study, aldehyde dehydrogenase (ALDH) activity was used as a basis to isolate and compare subpopulations of primary human prostate cancer cells and cell lines. ALDH-high prostate cancer cells displayed strongly elevated clonogenicity and migratory behavior in vitro. More strikingly, ALDH-high cells readily formed distant metastases with strongly enhanced tumor progression at both orthotopic and metastatic sites in preclinical models. Several ALDH isoforms were expressed in human prostate cancer cells and clinical specimens of primary prostate tumors with matched bone metastases. Our findings suggest that ALDH-based viable cell sorting can be used to identify and characterize tumor-initiating and, more importantly perhaps, metastasis-initiating cells in human prostate cancer.

Evaluation of association of HNF1B variants with diverse cancers: collaborative analysis of data from 19 genome-wide association studies

BACKGROUND

Genome-wide association studies have found type 2 diabetes-associated variants in the HNF1B gene to exhibit reciprocal associations with prostate cancer risk. We aimed to identify whether these variants may have an effect on cancer risk in general versus a specific effect on prostate cancer only.

METHODOLOGY/PRINCIPAL FINDINGS

In a collaborative analysis, we collected data from GWAS of cancer phenotypes for the frequently reported variants of HNF1B, rs4430796 and rs7501939, which are in linkage disequilibrium (r(2) = 0.76, HapMap CEU). Overall, the analysis included 16 datasets on rs4430796 with 19,640 cancer cases and 21,929 controls; and 21 datasets on rs7501939 with 26,923 cases and 49,085 controls. Malignancies other than prostate cancer included colorectal, breast, lung and pancreatic cancers, and melanoma. Meta-analysis showed large between-dataset heterogeneity that was driven by different effects in prostate cancer and other cancers. The per-T2D-risk-allele odds ratios (95% confidence intervals) for rs4430796 were 0.79 (0.76, 0.83)] per G allele for prostate cancer (p<10(-15) for both); and 1.03 (0.99, 1.07) for all other cancers. Similarly for rs7501939 the per-T2D-risk-allele odds ratios (95% confidence intervals) were 0.80 (0.77, 0.83) per T allele for prostate cancer (p<10(-15) for both); and 1.00 (0.97, 1.04) for all other cancers. No malignancy other than prostate cancer had a nominally statistically significant association.

CONCLUSIONS/SIGNIFICANCE

The examined HNF1B variants have a highly specific effect on prostate cancer risk with no apparent association with any of the other studied cancer types.

Circulating folate, vitamin B12, homocysteine, vitamin B12 transport proteins, and risk of prostate cancer: a case-control study, systematic review, and meta-analysis

BACKGROUND

Disturbed folate metabolism is associated with an increased risk of some cancers. Our objective was to determine whether blood levels of folate, vitamin B(12), and related metabolites were associated with prostate cancer risk.

METHODS

Matched case-control study nested within the U.K. population-based Prostate testing for cancer and Treatment (ProtecT) study of prostate-specific antigen-detected prostate cancer in men ages 50 to 69 years. Plasma concentrations of folate, B(12) (cobalamin), holo-haptocorrin, holo-transcobalamin total transcobalamin, and total homocysteine (tHcy) were measured in 1,461 cases and 1,507 controls. ProtecT study estimates for associations of folate, B(12), and tHcy with prostate cancer risk were included in a meta-analysis, based on a systematic review.

RESULTS

In the ProtecT study, increased B(12) and holo-haptocorrin concentrations showed positive associations with prostate cancer risk [highest versus lowest quartile of B(12) odds ratio (OR) = 1.17 (95% confidence interval, 0.95-1.43); P(trend) = 0.06; highest versus lowest quartile of holo-haptocorrin OR = 1.27 (1.04-1.56); P(trend) = 0.01]; folate, holo-transcobalamin, and tHcy were not associated with prostate cancer risk. In the meta-analysis, circulating B(12) levels were associated with an increased prostate cancer risk [pooled OR = 1.10 (1.01-1.19) per 100 pmol/L increase in B(12); P = 0.002]; the pooled OR for the association of folate with prostate cancer was positive [OR = 1.11 (0.96-1.28) per 10 nmol/L; P = 0.2) and conventionally statistically significant if ProtecT (the only case-control study) was excluded [OR = 1.18 (1.00-1.40) per 10 nmol/L; P = 0.02].

CONCLUSION

Vitamin B(12) and (in cohort studies) folate were associated with increased prostate cancer risk.

IMPACT

Given current controversies over mandatory fortification, further research is needed to determine whether these are causal associations.

Targeting chemotherapy to advanced bladder cancer patients most likely to benefit

Evaluation of: Vickers AJ, Cronin AM, Kattan MW et al.; The International Bladder Cancer Nomogram Consortium: Clinical benefits of a multivariate prediction model for bladder cancer: a decision analytic approach. Cancer 115(23), 5460-5469 (2009). The prognosis from muscle-invasive bladder cancer is poor. Improvements in survival can be made with the use of chemotherapy. The best results are obtained using multiagent regimens, which increase cure rates by approximately 5%. Thus, few patients benefit when compared with treatment morbidity. This low complete response rate makes powering of clinical trials difficult and may prevent them determining which patients benefit most from chemotherapy. Here, we discuss work by Vickers et al. reporting a decision-based analysis using a nomogram to determine the benefit for individual patients from chemotherapy. This decision aid can reduce the number of patients treated by 0.006, without compromising recurrence. The authors conclude that a nomogram-derived 25% risk threshold produced better targeting of chemotherapy than the current standard criteria (mostly using pathological stage).

Impact of prostate cancer testing: an evaluation of the emotional consequences of a negative biopsy result

BACKGROUND

When testing for prostate cancer, as many as 75% of men with a raised prostate-specific antigen (PSA) have a benign biopsy result. Little is known about the psychological effect of this result for these men.

METHODS

In all, 330 men participating in the prostate testing for cancer and treatment (ProtecT) study were studied; aged 50-69 years with a PSA level of > or = 3 ng ml(-1) and a negative biopsy result. Distress and negative mood were measured at four time-points: two during diagnostic testing and two after a negative biopsy result.

RESULTS

The majority of men were not greatly affected by testing or a negative biopsy result. The impact on psychological health was highest at the time of the biopsy, with around 20% reporting high distress (33 out of 171) and tense/anxious moods (35 out of 180). Longitudinal analysis on 195 men showed a significant increase in distress at the time of the biopsy compared with levels at the PSA test (difference in Impact of Events Scale (IES) score: 9.47; 95% confidence interval (CI) (6.97, 12.12); P<0.001). These levels remained elevated immediately after the negative biopsy result (difference in score: 7.32; 95% CI (5.51, 9.52); P<0.001) and 12 weeks later (difference in score: 2.42; 95% CI (0.50, 1.15); P=0.009). Psychological mood at the time of PSA testing predicted high levels of distress and anxiety at subsequent time-points.

CONCLUSIONS

Most men coped well with the testing process, although a minority experienced elevated distress at the time of biopsy and after a negative result. Men should be informed of the risk of distress relating to diagnostic uncertainty before they consent to PSA testing.

Abstract 1839: Alcohol intake and PSA levels in a European sample of middle-aged men invited for a PSA test

Prostate-specific antigen (PSA) is the most used biomarker for prostate cancer detection. As well as non-specific, PSA may be non-sensitive - diabetes, obesity, and other components of the metabolic syndrome like hypercholesterolemia generally lower its levels, whereas hypertension increases them. Alcohol use is associated with these factors. Any lowering effect of alcohol on PSA, mediated through its effect on the above factors or otherwise, is thus of great public health importance, as it could delay prostate cancer diagnosis in a significant number of men. Alcohol may also cause prostate cancer, but in the era of PSA testing this could be masked by detection bias, failing to identify cases among heavier drinkers.

The aim of this study is to investigate the relationship between alcohol intake and PSA levels in a sample of 10,000 white British men aged 50-70 years, without symptomatic prostate cancer.

Data on PSA levels, alcohol intake and prevalent components of the metabolic syndrome were available from a random sample of 10,000 men, 1,800 of whom had been genotyped for a functional variant in the alcohol dehydrogenase gene ADH1B. We used linear regression to compare geometric means of PSA among groups with differing alcohol intake in the year before PSA testing, with and without adjustment for BMI and a history of diabetes, hypertension and hypercholesterolemia. We also compared PSA levels of carriers of the ADH1B*A allele, who have been shown to drink less, with those of non-carriers, to remove potential confounding often present in alcohol associations.

After adjustment for age, BMI, centre, date of recruitment, and history of diabetes, hypertension and hypercholesterolemia, we found that PSA decreased with alcohol intake. Compared to men in the bottom third of the alcohol consumption distribution, those in the middle and top third had lower PSA (ratio of geometric means (RGM) and 95% confidence interval (CI): 0.96; 0.92-1.01 and 0.90; 0.85-0.94, respectively).

ADH1B*A carriers had on average lower PSA levels than non-carriers (RGM 0.82, 95% CI 0.66-1.01). This genotypic effect seemed more marked for those consuming &gt;= 10 units of alcohol a week, with geometric mean PSA among carriers 33% lower than among non-carriers (95% CI 5%-53%), whereas no effect was detected for light drinkers consuming &lt;10 units/week (RGM 0.98, 95% CI 0.66-1.47) (p for interaction=0.07).

Our analyses suggest the existence of a negative dose-response association of weekly alcohol consumption with PSA levels, independent of known determinants of PSA. Evidence of association with the ADH1B variant corroborates this finding and suggests a causal effect.

This is the first large population-based study to show evidence that alcohol lowers PSA levels. While independent replication of the findings is warranted, sensitivity analyses are already in progress to investigate the effect of recent changes in alcohol behavior (“sick quitter” effect).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1839.

Abstract 2843: Caspase-8 gene SNPs in prostate cancer susceptibility: a replication study

Introduction

A single nucleotide polymorphism (SNP) in the caspase-8 gene, (CASP8 D302H), has been reported to be involved in susceptibility to breast and pancreatic cancer, melanoma and glioma, but not colorectal or ovarian cancer. We previously have used a tagging-SNP approach to test the hypothesis that this SNP, or other variants in CASP8, were associated with prostate cancer, in 1009 cases, 987 men with normal serum prostate specific antigen (PSA) levels and 961 men with low serum PSA (&lt;0.5ng/ml). These subjects were drawn from those participating in the UK ProtecT (Prostate Testing for Cancer and Treatment) trial. Of the 15 tagging SNPs in caspase-8 that were genotyped, 7 showed some evidence of association with prostate cancer (P&lt;0.05). The aim of the present study was to attempt to replicate these results in an independent set of case and control subjects.

Methods

A further independent sample of men from the ProtecT trial formed the replication cohort for this study. Blood DNA samples were available for 1262 men with prostate cancer, 1258 men with normal serum PSA, and 609 men with low serum PSA. SNP genotyping was carried out by 5-prime nuclease PCR (TaqmanTM, Applied Biosystems). The association with prostate cancer was tested using logistic regression, controlling for sample set.

Results

Two SNPs with duplicate concordance rates of less than 98% were not included in the analysis. Genotype call rates for the remaining 5 SNPs were all greater than 95%, and genotype frequencies in control subjects were consistent with those expected under Hardy-Weinberg equilibrium. None of the 5 SNPs yielded significant evidence of association in the replication cohort, although some odds ratios were consistent between the two data sets. We combined the data from the test and replication cohorts to evaluate the overall evidence for association. The rare alleles of rs3769826 and rs6723097 conferred a reduced risk of prostate cancer with per-allele odds ratios (95% confidence interval) [OR(95%CI)] of 0.90 (0.82-0.98) and 0.88 (0.80-0.96), and P=0.013 and P=0.004 respectively. In addition, the deletion allele of the promoter indel rs3834129 conferred an increased risk of prostate cancer, with OR (95%CI) of 1.15 (1.05-1.27), P=0.003. While these results await further replication, it is interesting to note that the rare alleles of rs3769826 and rs6723097 are carried on European haplotypes that are associated with increased risk of breast cancer, suggesting the possibility of a different mode of action of caspase-8 in the two tumour types.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2843.

Abstract 470: The homing of prostate cancer to bone in vivo is modulated by Zoledronic acid

Cancer metastasis to the skeleton is a major problem with prostate cancer and requires the development of specialised approaches to treatment. Zoledronic acid, a bone resorptive agent, is currently the only bisphosphonate with proven benefit in prostate cancer. However, there is minimal research investigating whether Zoledronic acid modulates the early mechanisms involved in metastasis. The aim of this study is to determine whether different treatment regimes using Zoledronic acid modulate the early events in tumour/bone interactions.

Metatarsals from newborn mice (1-3 day old) are engrafted into a Dorsal Skinfold Chamber (DSC) implanted on a SCID mouse (5-6 weeks old). Prostate (PC3-GFP) cancer cells (1 × 105) are then injected via the heart (i.c) to simulate micrometastatic spread (n=20/group). Animals are treated with either i) weekly s.c injection of Zoledronic acid (25µg/kg/inection=100μg/kg in total) or saline or ii) single s.c injection of Zoledronic acid (100μg/kg) or saline for the 4 week study duration. The groups are further subdivided, so half of the animals receive treatment either before or after injection of tumour cells. Recordings of the chamber tissue and metatarsal are made at 48hr intervals for the duration of the experiment for the presence of PC3-GFP cells within the metatarsal. At the end of the study, tissue is harvested and processed for microCT, multi-photon analysis and histology.TreatmentNumber of PC3-GFP cells homing to metatarsalDay 3Day 9Day 15 Weekly treatment before PC3-GFP cells1.1 ± 0.1*1.3 ± 0.2*2.1 ± 0.3*Weekly treatment after PC3-GFP cells3.2 ± 0.5*3.4 ± 0.8*4.4 ± 0.7*Single treatment before PC3-GFP cells1.7 ± 0.3*8.9 ± 0.9*13.6 ± 0.8Control3.2 ± 0.714.7 ± 1.015.9 ± 1.4

Table 1. Number of PC3-GFP cells present in metatarsal after i.c. injection (*p&lt;0.05 compared to control).

Treatment with Zoledronic acid reduces tumour cell homing to bone. Weekly treatment of Zoledronic acid prior to prostate cancer cell administration reduces homing to bone to a greater extent than the other treatment regimes test.

Funded by Sixth European Framework Programme (PROMET).

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 470.

A polymorphism in the glucokinase gene that raises plasma fasting glucose, rs1799884, is associated with diabetes mellitus and prostate cancer: findings from a population-based, case-control study (the ProtecT study)

Epidemiological studies have identified a positive association between prostate cancer and recent onset type 2 diabetes mellitus but an increasingly inverse association with greater duration of type 2 diabetes. The mecha- nisms underlying these paradoxical associations are not clear. A single nucleotide polymorphism in the glucokinase gene, rs1799884, is associated with higher circulating plasma fasting glucose and with an increased risk of type 2 diabetes. We report a case-control study nested within the population-based Prostate testing for cancer and Treatment (ProtecT) study ISRCTN20141297. Men aged 50-69 years based around 9 UK cities were invited for a prostate specific antigen (PSA) test between June 2002 and November 2006. 1,551 cases and 2,993 controls were geno-typed. We observed suggestive evidence for a positive association between the AA variant rs1799884 and PSA-detected prostate cancer (OR(AA V GG)= 1.40, 95% CI= 0.95 to 2.07). There was little evidence that this effect was greater for more advanced stage/ grade cancers (OR(AA V GG)= 1.78, 95% CI= 0.99 to 3.21) versus less advanced cancers (OR(AA V GG)= 1.23, 95% CI= 0.77 to 1.94) (p for interaction = 0.33). The rs1799884 genotype was not associated with PSA concentration, suggesting that any effect on prostate cancer risk is not attributable to PSA detection bias. Our results provide suggestive evidence for a link between a genotype associated with type 2 diabetes mellitus and PSA-detected prostate cancer. We hypothesize that hyperglycaemia may be important in mediating this relationship.

Distinct microRNA alterations characterize high- and low-grade bladder cancer

Urothelial carcinoma of the bladder (UCC) is a common disease that arises by at least two different molecular pathways. The biology of UCC is incompletely understood, making the management of this disease difficult. Recent evidence implicates a regulatory role for microRNA in cancer. We hypothesized that altered microRNA expression contributes to UCC carcinogenesis. To test this hypothesis, we examined the expression of 322 microRNAs and their processing machinery in 78 normal and malignant urothelial samples using real-time rtPCR. Genes targeted by differentially expressed microRNA were investigated using real-time quantification and microRNA knockdown. We also examined the role of aberrant DNA hypermethylation in microRNA downregulation. We found that altered microRNA expression is common in UCC and occurs early in tumorogenesis. In normal urothelium from patients with UCC, 11% of microRNAs had altered expression when compared with disease-free controls. This was associated with upregulation of Dicer, Drosha, and Exportin 5. In UCC, microRNA alterations occur in a tumor phenotype-specific manner and can predict disease progression. High-grade UCC were characterized by microRNA upregulation, including microRNA-21 that suppresses p53 function. In low-grade UCC, there was downregulation of many microRNA molecules. In particular, loss of microRNAs-99a/100 leads to upregulation of FGFR3 before its mutation. Promoter hypermethylation is partly responsible for microRNA downregulation. In conclusion, distinct microRNA alterations characterize UCC and target genes in a pathway-specific manner. These data reveal new insights into the disease biology and have implications regarding tumor diagnosis, prognosis and therapy.

Association of folate-pathway gene polymorphisms with the risk of prostate cancer: a population-based nested case-control study, systematic review, and meta-analysis

Folate-pathway gene polymorphisms have been implicated in several cancers and investigated inconclusively in relation to prostate cancer. We conducted a systematic review, which identified nine case-control studies (eight included, one excluded). We also included data from four genome-wide association studies and from a case-control study nested within the UK population-based Prostate Testing for Cancer and Treatment study. We investigated by meta-analysis the effects of eight polymorphisms: MTHFR C677T (rs1801133; 12 studies; 10,745 cases; 40,158 controls), MTHFR A1298C (rs1801131; 5 studies; 3,176 cases; 4,829 controls), MTR A2756G (rs1805087; 8 studies; 7,810 cases; 37,543 controls), MTRR A66G (rs1801394; 4 studies; 3,032 cases; 4,515 controls), MTHFD1 G1958A (rs2236225; 6 studies; 7,493 cases; 36,941 controls), SLC19A1/RFC1 G80A (rs1051266; 4 studies; 6,222 cases; 35,821 controls), SHMT1 C1420T (rs1979277; 2 studies; 2,689 cases; 4,110 controls), and FOLH1 T1561C (rs202676; 5 studies; 6,314 cases; 35,190 controls). The majority (10 of 13) of eligible studies had 100% Caucasian subjects; only one study had <90% Caucasian subjects. We found weak evidence of dominant effects of two alleles: MTR 2756A>G [random effects pooled odds ratio, 1.06 (1.00-1.12); P = 0.06 (P = 0.59 for heterogeneity across studies)] and SHMT1 1420C>T [random effects pooled odds ratio, 1.11 (1.00-1.22); P = 0.05 (P = 0.38 for heterogeneity across studies)]. We found no effect of MTHFR 677C>T or any of the other alleles in dominant, recessive or additive models, or in comparing a/a versus A/A homozygous. Neither did we find any difference in effects on advanced or localized cancers. Our meta-analysis suggests that known common folate-pathway single nucleotide polymorphisms do not have significant effects on susceptibility to prostate cancer.

Associations of sexual dysfunction symptoms with PSA-detected localised and advanced prostate cancer: a case-control study nested within the UK population-based ProtecT (Prostate testing for cancer and Treatment) study

BACKGROUND

Sexual dysfunction might be symptomatic of cancer spreading beyond the prostate by local invasion, a mechanism of tumour progression associated with prognosis. Conversely, among men with raised prostate-specific antigen (PSA) levels, a negative association might be expected if sexual dysfunction was symptomatic of benign, rather than malignant, prostatic disease.

PATIENTS AND METHODS

Cases and controls were selected from among men recruited to the UK population-based ProtecT (Prostate testing for cancer and Treatment) study. Men aged 50-69 years were invited for PSA testing and those with a PSA level > or = 3.0 ng/ml were invited for biopsy. We investigated whether symptoms of sexual dysfunction, determined by self-completed questionnaire prior to biopsy, were associated with prostate cancer.

RESULTS

Of the 8924 men who had a PSA level> or = 3.0 ng/ml (11% of the men who had a PSA test), 6585 underwent biopsy of whom 2813 and 421, respectively, were subsequently diagnosed with localised and advanced prostate cancer and 3351 had a negative biopsy result. No individual symptom of sexual dysfunction was associated with risk of prostate cancer. The symptom score was associated with advanced (odds ratio (OR) per one unit increase in score=1.06; 1.00-1.12; P=0.07) but not with localised (OR=1.00; 0.97-1.02; P=0.9) prostate cancer (P=0.05 for heterogeneity).

CONCLUSIONS

Our study provides weak evidence that sexual dysfunction may be associated with PSA-detected advanced, but not localised, prostate cancer among men with raised PSA levels.

Population-based prostate-specific antigen testing in the UK leads to a stage migration of prostate cancer

OBJECTIVE

To determine, within the UK, the stage and grade of prostate cancers that would be found through population-based prostate specific antigen (PSA) testing and biopsy.

SUBJECTS AND METHODS

In the 'Prostate Testing for Cancer and Treatment' trial (ProtecT), men aged 50-69 years were recruited from nine cities in the UK and from randomly selected practices of general practitioners. Those with a PSA level of >3 ng/mL were offered a prostate biopsy. Age, PSA, stage and grade at diagnosis of ProtecT participants with cancer were compared with contemporaneous incident cases aged 50-69 years (age-restricted Cancer Registry cases) registered with the Eastern Cancer Registration and Information Centre (ECRIC).

RESULTS

Within ProtecT, 94,427 men agreed to be tested (50% of men contacted), 8807 ( approximately 9%) had a raised PSA level and 2022 (23%) had prostate cancer; 229 ( approximately 12%) had locally advanced (T3 or T4) or metastatic cancers, the rest having clinically localized (T1c or T2) disease. Within ECRIC, 12,661 cancers were recorded over the same period; 3714 were men aged 50-69 years at diagnosis. Men in ProtecT had a lower age distribution and PSA level, and the cancers were of lower stage and grade (P < 0.001 for all comparisons). If population-based PSA testing were introduced in the UK, approximately 2660 men per 100,000 aged 50-69 years would be found to have prostate cancer, compared to current rates of approximately 130 per 100,000. If half of men accepted PSA testing, approximately 160,000 cancers would be found, compared to 30,000 diagnosed each year at present.

CONCLUSIONS

Population-based PSA testing resulted in a significant downward stage and grade migration, and most such cancers were of low stage and grade, which could lead to risks of over-treatment for some men.

PTGS2-899G>C and prostate cancer risk: a population-based nested case-control study (ProtecT) and a systematic review with meta-analysis

Prostaglandin endoperoxidase synthase 2 is a key regulator of inflammation and may play a role in prostate carcinogenesis. The polymorphism, -899G>C (rs20417), alters a transcription factor-binding site and is associated with a reduced risk of colorectal adenoma. We tested the hypothesis that rs20417 may influence prostate cancer risk, using a large case-control study (n(cases)=1608, n(controls)=3058). We found no evidence that rs20417 alters prostate cancer risk (odds ratio (OR(CC & GC v GG)=1.05, 95% confidence interval (CI)=0.91-1.20). A meta-analysis of three studies also found little evidence that rs20417 alters risk (pooled OR(CC & GC v GG)=1.04, 95% CI=0.93-1.17), making it unlikely that rs20417 contributes in any major way to prostate cancer aetiology.

It's not just what you say, it's also how you say it: opening the 'black box' of informed consent appointments in randomised controlled trials

Randomised controlled trials (RCTs) represent the gold standard methodology for determining effectiveness of healthcare interventions. Poor recruitment to RCTs can threaten external validity and waste resources. An inherent tension exists between safeguarding informed decision-making by participants and maximising numbers enrolled. This study investigated what occurs during informed consent appointments in an ongoing multi-centre RCT in the UK. Objectives were to investigate: 1] how study staff presented study information to participants; 2] what evidence emerged as to how well-informed participants were when proceeding to randomisation or treatment selection; and 3] what aspects of the communication process may facilitate improvements in providing evidence of informed consent. Qualitative analysis of a purposive sample of 23 recruitment appointments from three study centres and involving several recruitment staff applied techniques of thematic, content and conversation analysis (CA). Thematic analysis and CA revealed variation in appointment content and structure. Appointments were mostly recruiter-led or participant-led, and this structure was associated with what evidence emerged as to how participants understood information provided and whether they were in equipoise. Participant-led appointments provided this evidence more consistently. Detailed CA identified communication techniques which, when employed by recruiters, provided evidence as to how participants understood the choices before them. Strategic use of open questions, pauses and ceding the floor in the interaction facilitated detailed and systematic exploration of each participant's concerns and position regarding equipoise. We conclude that the current focus on content to be provided to achieve informed consent should be broadened to encompass consideration of how information is best conveyed to potential participants. A model of tailored information provision using the communication techniques identified and centred on eliciting and addressing participants' concerns is proposed. Use of these techniques is necessary to make potential participants' understanding of key issues and their position regarding equipoise explicit in order to facilitate truly informed consent.

Development of a new method for monitoring prostate-specific antigen changes in men with localised prostate cancer: a comparison of observational cohorts

BACKGROUND

Prostate-specific antigen (PSA) measurements are increasingly used to monitor men with localised prostate cancer (PCa), but there is little consensus about the method to use.

OBJECTIVE

To apply age-specific predictions of PSA level (developed in men without cancer) to one cohort of men with clinically identified PCa and one cohort of men with PSA-detected PCa. We hypothesise that among men with clinically identified cancer, the annual increase in PSA level would be steeper than in men with PSA-detected cancer.

DESIGN, SETTING, AND PARTICIPANTS

The Scandinavian Prostate Cancer Group 4 (SPCG-4) cohort consisted of 321 men assigned to the watchful waiting arm of the SPCG-4 trial. The UK cohort consisted of 320 men with PSA-detected PCa in the Prostate testing for cancer and Treatment (ProtecT) study who opted for monitoring. Multilevel models describing changes in PSA level were fitted to the two cohorts, and average PSA level at age 50, change in PSA level with age, and predicted PSA values were derived.

MEASUREMENTS

PSA level.

RESULTS AND LIMITATIONS

In the SPCG-4 cohort, mean PSA at age 50 was similar to the cancer-free cohort but with a steeper yearly increase in PSA level (16.4% vs 4.0%). In the UK cohort, mean PSA level was higher than that in the cancer-free cohort (due to a PSA biopsy threshold of 3.0 ng/ml) but with a similar yearly increase in PSA level (4.1%). Predictions were less accurate for the SPCG-4 cohort (median difference between observed and predicted PSA level: -2.0 ng/ml; interquartile range [IQR]: -7.6-0.7 ng/ml) than for the UK cohort (median difference between observed and predicted PSA level: -0.8 ng/ml; IQR: -2.1-0.1 ng/ml).

CONCLUSIONS

In PSA-detected men, yearly change in PSA was similar to that in cancer-free men, whereas in men with symptomatic PCa, the yearly change in PSA level was considerably higher. Our method needs further evaluation but has promise for refining active monitoring protocols.

Identification of new genetic risk factors for prostate cancer

There is evidence that a substantial part of genetic predisposition to prostate cancer (PCa) may be due to lower penetrance genes which are found by genome-wide association studies. We have recently conducted such a study and seven new regions of the genome linked to PCa risk have been identified. Three of these loci contain candidate susceptibility genes: MSMB, LMTK2 and KLK2/3. The MSMB and KLK2/3 genes may be useful for PCa screening, and the LMTK2 gene might provide a potential therapeutic target. Together with results from other groups, there are now 23 germline genetic variants which have been reported. These results have the potential to be developed into a genetic test. However, we consider that marketing of tests to the public is premature, as PCa risk can not be evaluated fully at this stage and the appropriate screening protocols need to be developed. Follow-up validation studies, as well as studies to explore the psychological implications of genetic profile testing, will be vital prior to roll out into healthcare.

Imaging the effects of castration on bone turnover and hormone-independent prostate cancer colonization of bone

INTRODUCTION

Tumor populations may selectively colonize bone that is being actively remodeled. In prostate cancer patients, androgen deprivation directly inhibits tumor growth initially, whilst induced bone loss may facilitate tumor colonization of bone by androgen-insensitive cells. We have tested this hypothesis using a xenograft model of early growth of prostate cancer in bone.

METHODS

PC3 cells transfected with Green fluorescent protein (GFP) were injected into castrated and non-castrated athymic mice via intrabial and intracardiac routes. In vivo tumor growth was monitored daily and animals sacrificed 6-9 days following initial GFP-based detection of tumors. Tumor bearing and contra-lateral non-tumor bearing tibias were analyzed extensively by micro-CT and histology/immunohistochemistry for the presence of tumor cells and the effects of tumor and/or castration on bone cells and bone structure evaluated.

RESULTS

GFP-positive tumors in bone were visible from 12 days post-injection following intratibial injection, allowing tumors <1 mm diameter to be monitored in live animals. Castration did not affect tumor frequency, tumor volume, or time to initial appearance of tumors injected via intratibial or intracardiac routes. Castration decreased trabecular bone volume in all mice. Significant tumor-induced suppression of numbers of osteoblasts, coupled with increased numbers of activated osteoclasts, was evident in both intact animals and castrated animals.

CONCLUSIONS

In vivo GFP imaging allows the detection of early tumor growth at intra-osseous sites. Castration induces bone loss, but PC3-GFP cells are also capable of inducing bone remodeling in intact animals at early time points, independently of pre-existing castration-induced alterations to bone.

Factors distinguishing general practitioners who more readily participated in a large randomized trial were identified

OBJECTIVE

To investigate factors associated with the successful recruitment of general practices to a randomized controlled trial.

STUDY DESIGN AND SETTING

Analysis of accrual of primary care centers to a randomized controlled trial in the UK.

RESULTS

Those practices promptly agreeing to take part had better target achievement and a higher proportion of white British residents locally. Participating practices had a mean Quality and Outcomes Framework attainment of 92% of the points available, whereas nonparticipating practices achieved 88% (P=0.009). Participating practices were located in areas with a higher proportion of white British residents (mean 89%), in comparison to nonparticipating practices (mean 84%, P=0.004). Reasons given by practices to explain nonparticipation were primarily related to internal factors, with 38% of practices approached saying that they could not participate for such reasons.

CONCLUSION

There are some small differences between participating practices and nonparticipants in achievement of government targets and in the local ethnic mix. The primary reason given by practices for nonparticipation was workload or time pressures, with over a third of practices reporting being prevented by issues relating to practice organization. It may be that practices with workload or organizational difficulties require additional support to participate in research.

Multiple loci with different cancer specificities within the 8q24 gene desert

Recent studies based on genome-wide association, linkage, and admixture scan analysis have reported associations of various genetic variants in 8q24 with susceptibility to breast, prostate, and colorectal cancer. This locus lies within a 1.18-Mb region that contains no known genes but is bounded at its centromeric end by FAM84B and at its telomeric end by c-MYC, two candidate cancer susceptibility genes. To investigate the associations of specific loci within 8q24 with specific cancers, we genotyped the nine previously reported cancer-associated single-nucleotide polymorphisms across the region in four case-control sets of prostate (1854 case subjects and 1894 control subjects), breast (2270 case subjects and 2280 control subjects), colorectal (2299 case subjects and 2284 control subjects), and ovarian (1975 case subjects and 3411 control subjects) cancer. Five different haplotype blocks within this gene desert were specifically associated with risks of different cancers. One block was solely associated with risk of breast cancer, three others were associated solely with the risk of prostate cancer, and a fifth was associated with the risk of prostate, colorectal, and ovarian cancer, but not breast cancer. We conclude that there are at least five separate functional variants in this region.

FGFR3 mutations indicate better survival in invasive upper urinary tract and bladder tumours

BACKGROUND

Promoter hypermethylation and microsatellite instability are frequent in tumours of the upper urinary tract (UTT) and infrequent in bladder tumours. FGFR3 mutations are common findings in bladder tumours and are associated with a good prognosis.

OBJECTIVE

To investigate the occurrence of FGFR3 mutations in UTT and determine the prognostic effect of these genetic changes.

DESIGN, SETTING, AND PARTICIPANTS

Tissue from the initial tumour was obtained from 280 patients (117 bladder tumours and 163 UTT). Patients were selected from pathologic archives to represent the disease spectrum of UCC throughout the urinary tract. Following UCC excision, patients underwent surveillance for a median of 56 mo (range 1-216 mo) or until death.

MEASUREMENTS

FGFR3 mutation analysis was successfully performed on 252 of the 280 primary tumours using the SNaPshot method. Two-tailed statistical analyses were done using the chi(2), Fisher exact tests, and log rank tests. Cox proportional hazard ratios were estimated to obtain risks of recurrence, progression, and death, and to find independent prognostic factors in a multivariate model.

RESULTS AND LIMITATIONS

FGFR3 mutations occurred with the same frequency in bladder and upper tract tumours. Mutations were associated with low-stage tumours and a milder disease course in bladder, ureter, and renal pelvis tumours. Strikingly, our data suggest that these mutations indicate a better survival in patients with invasive tumours from the bladder and upper urinary tract.

CONCLUSIONS

FGFR3 mutation status might be used to select patients with invasive UCC who have a lower risk of death.

Promoter methylation correlates with reduced Smad4 expression in advanced prostate cancer

BACKGROUND

Transforming growth factor-beta (TGF-beta) is a potent growth inhibitor in a wide range of cell types. A transducer of TGF-beta signaling known as Mothers against decapentaplegic homologue 4 (Smad4) is a known tumor suppressor found on chromosome 18q21.1 and is typically inactivated by deletion or mutation in pancreatic and colorectal cancers. The purpose of the article is to investigate Smad4 expression, gene copy number and methylation status in advanced cases of prostate cancer.

METHODS

We have employed Methylation Specific PCR (MSP) to identify methylation sites within the Smad4 promoter and combined this with quantitative real-time PCR to look for correlates between methylation status and Smad4 expression and to examine androgen receptor (AR) expression. Bacterial artificial chromosome-comparative genomic hybridization (BAC-CGH) has been used to look for genomic amplifications and deletions which may also contribute to expression changes.

RESULTS

We fail to find evidence of genomic deletions or amplifications affecting the Smad4 locus on chromosome 18 but show a correlation between promoter methylation and the loss of Smad4 expression in the same material. We confirm that the AR locus on the X chromosome is amplified in 30% of the advanced clinical samples and that this correlates with increased transcript levels as previously reported by other groups.

CONCLUSION

This indicates that epigenetic changes affect the expression of the Smad4 protein in prostate cancer and points to methylation of the promoter as a novel marker of and contributor to the disease warranting further study.

BMP-6 over-expression in prostate cancer is associated with increased Id-1 protein and a more invasive phenotype

Bone morphogenetic protein-6 (BMP-6) has been strongly implicated in prostate cancer development and bone metastasis. Our previous data showed that BMP-6 mRNA was absent in patients with benign prostatic hyperplasia, but evident in primary tumours with established secondary skeletal metastases. To examine the role of BMP-6 in prostate cancer progression, we have developed a BMP-6-regulatable, doxycycline-inducible gene expression system. BMP-6 induction by doxycycline addition led to increased levels of BMP-6 RNA and protein, associated with nuclear translocation of SMADs and activation of the downstream target gene Id-1. BMP-6 protein did not enhance the proliferation rate of PC3M cells but did significantly increase the rate of migration and invasion in both PC3M and DU145 cells. Increased metalloproteinase (MMP-1 and MMP-9) mRNA levels were also observed following BMP-6 induction. Luciferase reporter assays confirmed BMP-6-mediated activation of MMP-1 and MMP-9 promoters, indicating direct transcriptional activation of MMPs by BMP-6. BMP-6 stimulation also led to an increase in phosphorylation levels of MAPK proteins. We next examined the effects of BMP-6 on the downstream gene Id-1 in a cohort of prostate cancer patients. A tissue microarray (TMA) was constructed and samples stained for BMP-6 and Id-1 expression. We observed a significant increase in the intensity of staining of epithelial BMP-6 in the cancer cases compared to the benign cases (Mann-Whitney U test, p < 0.0005) and in the intensity of staining of epithelial Id-1 in the cancer cases compared to the benign cases (Mann-Whitney U test, p = 0.015). We further observed a significant positive correlation between epithelial staining for Id-1 and BMP-6 (p = 0.001) across all samples for both benign and cancer cases. These data demonstrate that BMP-6 promotes migration and invasion of prostate cancer cells, potentially through activation of Id-1 and MMP activation.

A comparison of the performance of microsatellite and methylation urine analysis for predicting the recurrence of urothelial cell carcinoma, and definition of a set of markers by Bayesian network analysis

OBJECTIVE

To compare the potential of two diagnostic methods for detecting recurrence of urothelial cell carcinoma (UCC) of the bladder, by (i) detecting alterations in microsatellite DNA markers and loss of heterozygosity (LOH), and (ii) detecting aberrant gene hypermethylation, as UCC has a high recurrence rate in the urinary tract and the disease can invade muscle if new tumours are overlooked.

PATIENTS AND METHODS

Over 1 year, urine samples were retrieved from 40 patients already diagnosed with bladder UCC (30 pTa, two pTis, eight pT1). Samples were collected 6 months after bladder tumour resection, during the follow-up schedule. We used samples to analyse nine microsatellite markers and the methylation status of 11 gene promoters. Receiver operating characteristic curves were generated and Bayesian statistics used to create an interaction network between recurrence and the biomarkers.

RESULTS

During the study, 15 of the 40 patients (38%) had a tumour recurrence and 14 were identified by cystoscopy (reference method). Overall, microsatellite markers (area under curve, AUC 0.819, 95% confidence interval, CI, 0.677-0.961) had better performance characteristics than promoter hypermethylation (AUC 0.448, 0.259-0.637) for detecting recurrence. A marker panel of IFNA, MBP, ACTBP2, D9S162 and of RASSF1A, and WIF1 generated a higher diagnostic accuracy of 86% (AUC 0.92, 0.772-0.981).

CONCLUSION

Microsatellite markers have better performance characteristics than promoter hypermethylation for detecting UCC recurrence. These data support the further development of a combination of only six markers from both methods in urinary DNA. Once validated, it could be used routinely during the follow-up for the early detection and surveillance of UCC from the lower and upper urinary tract.

The Polycomb Group protein EZH2 regulates actin polymerization in human prostate cancer cells

BACKGROUND

The Polycomb Group protein EZH2 is implicated in prostate cancer progression. EZH2 promotes prostate cancer cell proliferation and invasiveness. We describe a link between EZH2 function and actin polymerization in prostate cancer cells.

METHODS

Nuclear and cytoplasmic EZH2 expression in benign and malignant prostate tissue samples was assessed. An association between EZH2 function and actin polymerization in prostate cancer cells was investigated using siRNA-mediated knock-down of EZH2. Effects of EZH2 knock-down on actin polymerization dynamics were analyzed biochemically using immunoblot analysis of cell lysate fractions, and morphologically using immunocytochemistry.

RESULTS

Cytoplasmic EZH2 is expressed at low levels in benign prostate epithelial cells and over-expressed in prostate cancer cells. Cytoplasmic EZH2 expression levels correlate with nuclear EZH2 expression in prostate cancer samples. Knock-down of EZH2 in PC3 prostate cancer cells increases the amount of F-actin polymerization, cell size, and formation of actin-rich filaments.

CONCLUSIONS

Cytoplasmic EZH2 is over-expressed in prostate cancer cells. EZH2 function promotes a reduction in the pool of insoluble F-actin in invasive prostate cancer cells. EZH2 may regulate actin polymerization dynamics and thereby promote prostate cancer cell motility and invasiveness.