Only a minority of the genetic component of prostate cancer (PrCa) risk has been explained. Some observed associations of single nucleotide polymorphisms (SNPs) with PrCa might arise from associations of these SNPs with circulating prostate specific antigen (PSA) because PSA values are used to select controls.
We undertook a genome-wide association study (GWAS) of screen detected PrCa (ProtecT 1146 cases and 1804 controls); meta-analysed the results with those from the previously published UK Genetic Prostate Cancer Study (1854 cases and 1437 controls); investigated associations of SNPs with PrCa using either ‘low’ (PSA <0.5ng/ml) or ‘high’ (PSA ≥3ng/ml, biopsy negative) PSA controls; and investigated associations of SNPs with PSA.
The ProtecT GWAS confirmed previously reported associations of PrCa at 3 loci: 10q11.23, 17q24.3 and 19q13.33. The meta-analysis confirmed associations of PrCa with SNPs near 4 previously identified loci (8q24.21,10q11.23, 17q24.3 and 19q13.33). When comparing PrCa cases with low PSA controls, alleles at genetic markers rs1512268, rs445114, rs10788160, rs11199874, rs17632542, rs266849 and rs2735839 were associated with an increased risk of PrCa, but the effect-estimates were attenuated to the null when using high PSA controls (p for heterogeneity in effect-estimates<0.04). We found a novel inverse association of rs9311171-T with circulating PSA.
Differences in effect estimates for PrCa observed when comparing low vs. high PSA controls, may be explained by associations of these SNPs with PSA.
These findings highlight the need for inferences from genetic studies of PrCa risk to carefully consider the influence of control selection criteria.
Prostate Specific Antigen; research design; prostate cancer; case-control studies; genome wide association studies
Vitamin D pathway single nucleotide polymorphisms (SNPs) are potentially useful proxies for investigating whether circulating vitamin D metabolites [total 25-hydroxyvitamin-D, 25(OH)D; 1,25-dihydroxyvitamin, 1,25(OH)2D] are causally related to prostate cancer. We investigated associations of sixteen SNPs across seven genes with prostate-specific antigen-detected prostate cancer.
In a nested case–control study (within the ProtecT trial), we estimated odds ratios and 95 % confidence intervals (CIs) quantifying associations between SNPs and prostate cancer. Subgroup analyses investigated whether associations were stronger in men who had high/low sun exposure [a proxy for 25(OH)D]. We quantified associations of SNPs with stage (T1–T2/T3–T4) and grade (<7/≥7). Multiple variant scores included SNPs encoding proteins involved in 25(OH)D synthesis and metabolism.
We included 1,275 prostate cancer cases (141 locally advanced, 385 high grades) and 2,062 healthy controls. Vitamin D-binding protein SNPs were associated with prostate cancer (rs4588-A: OR 1.20, CI 1.01, 1.41, p = 0.04; rs7041-T: OR 1.19, CI 1.02, 1.38, p = 0.03). Low 25(OH)D metabolism score was associated with high (vs low) grade (OR 0.76, CI 0.63, 0.93, p = 0.01); there was a similar association of its component variants: rs6013897-A in CYP24A1 (OR 0.78, CI 0.60, 1.01, p = 0.06) and rs10877012-T in CYP27B1 (OR 0.80, CI 0.63, 1.02, p = 0.07). There was no evidence that associations differed by level of sun exposure.
We found some evidence that vitamin D pathway SNPs were associated with prostate cancer risk and grade, but not stage. There was no evidence of an association in men with deficient vitamin D (measured by having low sun exposure).
Electronic supplementary material
The online version of this article (doi:10.1007/s10552-014-0500-5) contains supplementary material, which is available to authorized users.
Prostate cancer; Vitamin D; Vitamin D pathway genes; 25 hydroxyvitamin-D; 1,25-dihydroxyvitamin-D
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 realtime rtPCR. Genes targeted by differentially expressed microRNA were investigated using realtime quantification and microRNA knock-down. We also examined the role of aberrant DNA hypermethylation in microRNA down-regulation. We found that altered microRNA expression is common in UCC and occurs early in tumorogenesis. In normal urothelium from patients with UCC 11% of microRNA’s had altered expression when compared to 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 down-regulation of many microRNA molecules. In particular, loss of microRNAs-99a/100 leads to upregulation of FGFR3 prior to its mutation. Promoter hypermethylation is partly responsible for microRNA down-regulation. 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.
Prostate cancer (PC) incidence and progression may be influenced by dietary factors, but little is known about the acceptability of dietary modification to men at increased risk of PC. Qualitative interviews with men participating in the ProDiet study were undertaken to explore the feasibility of implementing dietary interventions for the prevention of prostate cancer.
An interview study nested within the ProDiet randomised feasibility trial of dietary interventions to prevent a PC diagnosis. Men (n = 133) who previously participated in community based prostate specific antigen (PSA) testing without PC but who were at increased risk of the disease were randomly allocation to both lycopene (lycopene or placebo capsules or lycopene rich diet) and green tea (green tea or placebo capsules or green tea drink) for 6 months. Semi-structured interviews were conducted with participants shortly after randomisation, to investigate attitudes towards dietary modification for PC prevention and dietary information. Interviews were audio-recorded, transcribed and analysed to identify common themes.
Interviews were conducted with 21 participants aged 52-72 years with PSA levels between 2.5 and 2.95 ng/ml, or a negative prostate biopsy result. Most men identified the major causes of cancer in general to include diet, environment, ageing and genetic factors. This contrasted sharply with men’s uncertainty about PC aetiology, and the function of the prostate. Men were confused by conflicting messages in the media about dietary practices to promote health overall, but were positive about the potential of lycopene and green tea in relation to PC prevention, valuing their natural components. Furthermore these men wanted tailored dietary advice for PC prevention from their clinicians, whom they considered a trusted source of information.
Men at elevated risk of PC reported uncertainty about PC aetiology and the role of diet in PC prevention, but enthusiasm for dietary modifications that were perceived as ‘simple’ and ‘natural’. The men looked to clinicians to provide consistent disease specific dietary advice. These factors should be taken into consideration by clinicians discussing elevated PSA results with patients and those planning to embark on future trials investigating dietary modification interventions for the prevention of a PC diagnosis.
Diet; Green Tea; Lycopene; Prostatic neoplasms; Qualitative research
Toll-like receptor 4 (TLR4) is one of the best known TLR members expressed on the surface of several leukocytes and tissue cells and has a key function in detecting pathogen and danger-associated molecular patterns. The role of TLR4 in the pathophysiology of several age-related diseases is also well recognized, such as prostate cancer (PCa). TLR4 polymorphisms have been related to PCa risk, but the relationship between TLR4 genotypes and aggressive PCa risk has not been evaluated by any systematic reviews.
We performed a systematic review and meta-analysis of candidate-gene and genome-wide association studies analyzing this relationship and included only white population. Considering appropriate criteria, only nine studies were analyzed in the meta-analysis, including 3,937 aggressive PCa and 7,382 controls.
Using random effects model, no significant association was found in the ten TLR4 SNPs reported by at least four included studies under any inheritance model (rs2737191, rs1927914, rs10759932, rs1927911, rs11536879, rs2149356, rs4986790, rs11536889, rs7873784, and rs1554973). Pooled estimates from another ten TLR4 SNPs reported by three studies also showed no significant association (rs10759930, rs10116253, rs11536869, rs5030717, rs4986791, rs11536897, rs1927906, rs913930, rs1927905, and rs7045953). Meta-regression revealed that study type was not a significant source of between-study heterogeneity.
TLR4 polymorphisms were not significantly associated with the risk of aggressive PCa.
Men with germline BRCA1/2 mutations have a higher risk of developing prostate cancer than non-carriers. IMPACT is an international consortium of 62 centres in 20 countries evaluating the use of targeted PrCa screening in men with BRCA1/2 mutations.
To report the first year’s screening results for all men at enrolment in the study.
Outcome Measurements and Statistical Analysis
PSA levels, PrCa incidence, and tumour characteristics were evaluated. Fisher’s exact test was used to compare the number of PrCa cases between groups and differences between disease types.
Design, setting and participants
We recruited men aged 40–69 years with germline BRCA1/2 mutations and a control group of men who have tested negative for a pathogenic BRCA1 or BRCA2 mutation known to be present in their family. All men underwent PSA testing at enrolment and those with a PSA >3ng/ml offered prostate biopsy.
Results and limitations
We recruited 2,481 men (791 BRCA1 carriers, 531 BRCA1 controls; 731 BRCA2 carriers, 428 BRCA2 controls). 199 (8%) presented with a PSA >3ng/ml, 162 biopsies were performed and 59 PrCas diagnosed (18 BRCA1 carriers, 10 BRCA1 controls; 24 BRCA2 carriers, 7 BRCA2 controls); 66% of tumours were classified as intermediate or high-risk disease. The positive-predictive-value for biopsy using a PSA threshold of 3.0ng/ml in BRCA2 mutation carriers was 48%, double that reported in population screening studies. A significant difference in detecting intermediate or high-risk disease was observed in BRCA2 carriers. 95% of men were Caucasian thus the results cannot be generalised to all ethnic groups.
The IMPACT screening network will be useful for targeted PrCa screening studies in men with germline genetic risk variants as they are discovered. These preliminary results support the use of targeted PSA screening based on BRCA genotype and show that this yields a high proportion of aggressive disease.
In this report we demonstrate that germline genetic markers can be used to identify men at higher risk of PrCa. Targeting screening at these men resulted in the identification of tumours that were more likely to require treatment.
BRCA1; BRCA2; Prostate cancer; Prostate-Specific-Antigen; Targeted screening
Kohonen self-organizing maps (SOMs) are unsupervised Artificial Neural Networks (ANNs) that are good for low-density data visualization. They easily deal with complex and nonlinear relationships between variables. We evaluated molecular events that characterize high- and low-grade BC pathways in the tumors from 104 patients. We compared the ability of statistical clustering with a SOM to stratify tumors according to the risk of progression to more advanced disease. In univariable analysis, tumor stage (log rank P = 0.006) and grade (P < 0.001), HPV DNA (P < 0.004), Chromosome 9 loss (P = 0.04) and the A148T polymorphism (rs 3731249) in CDKN2A (P = 0.02) were associated with progression. Multivariable analysis of these parameters identified that tumor grade (Cox regression, P = 0.001, OR.2.9 (95% CI 1.6–5.2)) and the presence of HPV DNA (P = 0.017, OR 3.8 (95% CI 1.3–11.4)) were the only independent predictors of progression. Unsupervised hierarchical clustering grouped the tumors into discreet branches but did not stratify according to progression free survival (log rank P = 0.39). These genetic variables were presented to SOM input neurons. SOMs are suitable for complex data integration, allow easy visualization of outcomes, and may stratify BC progression more robustly than hierarchical clustering.
Bladder cancer; Kohonen self-organizing map; molecular markers; progression
Men with germline breast cancer 1, early onset (BRCA1) or breast cancer 2, early onset (BRCA2) gene mutations have a higher risk of developing prostate cancer (PCa) than noncarriers. IMPACT (Identification of Men with a genetic predisposition to ProstAte Cancer: Targeted screening in BRCA1/2 mutation carriers and controls) is an international consortium of 62 centres in 20 countries evaluating the use of targeted PCa screening in men with BRCA1/2 mutations.
To report the first year's screening results for all men at enrolment in the study.
Design, setting and participants
We recruited men aged 40–69 yr with germline BRCA1/2 mutations and a control group of men who have tested negative for a pathogenic BRCA1 or BRCA2 mutation known to be present in their families. All men underwent prostate-specific antigen (PSA) testing at enrolment, and those men with PSA >3 ng/ml were offered prostate biopsy.
Outcome measurements and statistical analysis
PSA levels, PCa incidence, and tumour characteristics were evaluated. The Fisher exact test was used to compare the number of PCa cases among groups and the differences among disease types.
Results and limitations
We recruited 2481 men (791 BRCA1 carriers, 531 BRCA1 controls; 731 BRCA2 carriers, 428 BRCA2 controls). A total of 199 men (8%) presented with PSA >3.0 ng/ml, 162 biopsies were performed, and 59 PCas were diagnosed (18 BRCA1 carriers, 10 BRCA1 controls; 24 BRCA2 carriers, 7 BRCA2 controls); 66% of the tumours were classified as intermediate- or high-risk disease. The positive predictive value (PPV) for biopsy using a PSA threshold of 3.0 ng/ml in BRCA2 mutation carriers was 48%—double the PPV reported in population screening studies. A significant difference in detecting intermediate- or high-risk disease was observed in BRCA2 carriers. Ninety-five percent of the men were white, thus the results cannot be generalised to all ethnic groups.
The IMPACT screening network will be useful for targeted PCa screening studies in men with germline genetic risk variants as they are discovered. These preliminary results support the use of targeted PSA screening based on BRCA genotype and show that this screening yields a high proportion of aggressive disease.
In this report, we demonstrate that germline genetic markers can be used to identify men at higher risk of prostate cancer. Targeting screening at these men resulted in the identification of tumours that were more likely to require treatment.
Take Home Message
This report demonstrates that germline genetic markers can be used to identify men at higher risk of prostate cancer. Targeting screening at these higher-risk men resulted in the identification of tumours that were more likely to require treatment.
BRCA1; BRCA2; Prostate cancer; Prostate-specific antigen; Targeted screening
Patients’ treatment preferences are often cited as barriers to recruitment in randomized controlled trials (RCTs). We investigated how RCT recruiters reacted to patients’ treatment preferences and identified key strategies to improve informed decision-making and trial recruitment.
Audio-recordings of 103 RCT recruitment appointments with 96 participants in three UK multicenter pragmatic RCTs were analyzed using content and thematic analysis. Recruiters’ responses to expressed treatment preferences were assessed in one RCT (ProtecT - Prostate testing for cancer and Treatment) in which training on exploring preferences had been given, and compared with two other RCTs where this specific training had not been given.
Recruiters elicited treatment preferences similarly in all RCTs but responses to expressed preferences differed substantially. In the ProtecT RCT, patients’ preferences were not accepted at face value but were explored and discussed at length in three key ways: eliciting and acknowledging the preference rationale, balancing treatment views, and emphasizing the need to keep an open mind and consider all treatments. By exploring preferences, recruiters enabled participants to become clearer about whether their views were robust enough to be sustained or were sufficiently weak that participation in the RCT became possible. Conversely, in the other RCTs, treatment preferences were often readily accepted without further discussion or understanding the reasoning behind them, suggesting that patients were not given the opportunity to fully consider all treatments and trial participation.
Recruiters can be trained to elicit and address patients’ treatment preferences, enabling those who may not have considered trial participation to do so. Without specific guidance, some RCT recruiters are likely to accept initial preferences at face value, missing opportunities to promote more informed decision-making. Training interventions for recruiters that incorporate key strategies to manage treatment preferences, as in the ProtecT study, are required to facilitate recruitment and informed consent.
ProtecT RCT: Current Controlled Trials ISRCTN20141297. The other two trials are registered but have asked to be anonymized.
Treatment preferences; Qualitative research methods; Randomized controlled trials; Recruitment to randomized controlled trials; Informed consent; ProtecT study
The aim of the study was to investigate how doctors considered and experienced the concept of equipoise while recruiting patients to randomized controlled trials (RCTs).
Study Design and Setting
In-depth interviews with 32 doctors in six publicly funded pragmatic RCTs explored their perceptions of equipoise as they undertook RCT recruitment. The RCTs varied in size, duration, type of complex intervention, and clinical specialties. Interview data were analyzed using qualitative content and thematic analytical methods derived from grounded theory and synthesized across six RCTs.
All six RCTs suffered from poor recruitment. Doctors wanted to gather robust evidence but experienced considerable discomfort and emotion in relation to their clinical instincts and concerns about patient eligibility and safety. Although they relied on a sense of community equipoise to justify participation, most acknowledged having “hunches” about particular treatments and patients, some of which undermined recruitment. Surgeons experienced these issues most intensely. Training and support promoted greater confidence in equipoise and improved engagement and recruitment.
Recruitment to RCTs is a fragile process and difficult for doctors intellectually and emotionally. Training and support can enable most doctors to become comfortable with key RCT concepts including equipoise, uncertainty, patient eligibility, and randomization, promoting a more resilient recruitment process in partnership with patients.
Randomized controlled trials; Recruitment; Equipoise; Uncertainty; Qualitative research; Uncertainty; Training
The diagnosis of prostate cancer (PC) can provide a trigger for dietary change, and there is evidence that healthier diets may improve quality of life and clinical outcomes. However, men’s views about dietary change in PC survivorship are largely unknown. This multi-centre qualitative interview study explored men’s views about dietary change in PC survivorship, to better understand motivations for, and barriers to, achieving desired changes. The role of radical and active surveillance treatments on dietary change and the influence of men’s partners were examined. Focus groups also evaluated stakeholder opinion, including healthcare professionals, about the provision of dietary advice to PC patients.
A multi-centre interview study explored views about diet and motivations for, and barriers to, dietary change in men at elevated risk or diagnosed with PC following prostate specific antigen (PSA) testing. 58 men and 11 partners were interviewed. Interviews and focus groups were undertaken with 11 healthcare professionals, 5 patients and 4 partners to evaluate stakeholders’ opinions about the feasibility and acceptability of providing dietary advice to PC patients. Data were analysed using methods of constant comparison and thematic analysis.
Over half of diagnosed men reported making dietary changes, primarily to promote general or prostate health or facilitate coping, despite their uncertainty about diet-PC links. Interest in dietary advice was high. Information needs varied depending on treatment received, with men on active surveillance more frequently modifying their diet and regarding this as an adjunct therapy. Men considered their partners integral to implementing changes. Provision of dietary advice to men diagnosed with PC was considered by healthcare professionals and men to be feasible and appropriate in the context of a holistic ‘care package’.
Many men make positive dietary changes after PC diagnosis, which are perceived by men and their partners to bring psychological and general health benefits and could help future dietary intervention trials. Men and their partners desire more and better dietary information that may support PC survivorship, particularly among those embarking on active surveillance/monitoring programmes. There are opportunities for healthcare professionals to support PC patients both clinically and psychologically by the routine integration of healthy eating advice into survivorship care plans.
Cancer; Diet; Oncology; Prostatic neoplasms; Qualitative research; Survivors
The HOXB13 gene has been implicated in prostate cancer (PrCa) susceptibility. We performed a high resolution fine-mapping analysis to comprehensively evaluate the association between common genetic variation across the HOXB genetic locus at 17q21 and PrCa risk. This involved genotyping 700 SNPs using a custom Illumina iSelect array (iCOGS) followed by imputation of 3195 SNPs in 20,440 PrCa cases and 21,469 controls in The PRACTICAL consortium. We identified a cluster of highly correlated common variants situated within or closely upstream of HOXB13 that were significantly associated with PrCa risk, described by rs117576373 (OR 1.30, P = 2.62×10−14). Additional genotyping, conditional regression and haplotype analyses indicated that the newly identified common variants tag a rare, partially correlated coding variant in the HOXB13 gene (G84E, rs138213197), which has been identified recently as a moderate penetrance PrCa susceptibility allele. The potential for GWAS associations detected through common SNPs to be driven by rare causal variants with higher relative risks has long been proposed; however, to our knowledge this is the first experimental evidence for this phenomenon of synthetic association contributing to cancer susceptibility.
Genome-wide association studies (GWAS) have identified numerous low penetrance disease susceptibility variants, yet few causal alleles have been unambiguously identified. The underlying causal variants are expected to be predominantly common; however synthetic associations with rare, higher penetrance variants have been hypothesised though not yet observed. Here, we report detection of a novel common, low penetrance prostate cancer association at the HOXB locus at ch17q and show that this signal can actually be attributed to a previously identified rare, moderate penetrance coding variant (G84E) in HOXB13. This study therefore provides the first experimental evidence for the existence of synthetic associations in cancer and shows that where GWAS signals arise through this phenomenon, risk predictions derived using the tag SNP would substantially underestimate the relative risk conferred and overestimate the number of carriers of the causal variant. Synthetic associations at GWAS signals could therefore account for a proportion of the missing heritability of complex diseases.
Genome-wide association studies (GWAS) have identified multiple common genetic variants associated with an increased risk of prostate cancer (PrCa), but these explain less than one-third of the heritability. To identify further susceptibility alleles, we conducted a meta-analysis of four GWAS including 5953 cases of aggressive PrCa and 11 463 controls (men without PrCa). We computed association tests for approximately 2.6 million SNPs and followed up the most significant SNPs by genotyping 49 121 samples in 29 studies through the international PRACTICAL and BPC3 consortia. We not only confirmed the association of a PrCa susceptibility locus, rs11672691 on chromosome 19, but also showed an association with aggressive PrCa [odds ratio = 1.12 (95% confidence interval 1.03–1.21), P = 1.4 × 10−8]. This report describes a genetic variant which is associated with aggressive PrCa, which is a type of PrCa associated with a poorer prognosis.
Prostate cancer is the most frequently diagnosed cancer in males in developed countries. To identify common prostate cancer susceptibility alleles, we genotyped 211,155 SNPs on a custom Illumina array (iCOGS) in blood DNA from 25,074 prostate cancer cases and 24,272 controls from the international PRACTICAL Consortium. Twenty-three new prostate cancer susceptibility loci were identified at genome-wide significance (P < 5 × 10−8). More than 70 prostate cancer susceptibility loci, explaining ~30% of the familial risk for this disease, have now been identified. On the basis of combined risks conferred by the new and previously known risk loci, the top 1% of the risk distribution has a 4.7-fold higher risk than the average of the population being profiled. These results will facilitate population risk stratification for clinical studies.
Ecological and epidemiological studies have identified an inverse association of intensity and duration of sunlight exposure with prostate cancer, which may be explained by a reduction in vitamin D synthesis. Pigmentation traits influence sun exposure and therefore may affect prostate cancer risk. Because observational studies are vulnerable to confounding and measurement error, we used Mendelian randomization to examine the relationship of sun exposure with both prostate cancer risk and the intermediate phenotype, plasma levels of vitamin D.
We created a tanning, a skin color and a freckling score as combinations of SNPs that have been previously associated with these phenotypes. A higher score indicates propensity to burn, have a lighter skin color and freckles. The scores were tested for association with vitamin D levels (25-hydroxyvitamin-D and 1,25-dihydroxyvitamin-D) and PSA-detected prostate cancer in 3123 white British individuals enrolled in the Prostate Testing for cancer and Treatment (ProtecT) study.
The freckling score was inversely associated with 25(OH)D levels (change in 25(OH)D per score unit −0.27; 95%CI: −0.52, −0.01), and the tanning score was positively associated with prostate cancer risk (OR 1.05; 95%CI: 1.02,1.09), after adjustment for population stratification and potential confounders.
Individuals who tend to burn are more likely to spend less time in the sun and consequently have lower plasma vitamin D levels and higher susceptibility to prostate cancer.
The use of pigmentation related genetic scores is valuable for the assessment of the potential benefits of sun exposure with respect to prostate cancer risk.
pigmentation; tanning; sun exposure; vitamin D; prostate cancer
Alcohol is an established carcinogen but not an established risk factor for prostate cancer, despite some recent prospective studies suggesting increased risk among heavy drinkers. The aim of this study was to investigate the role of alcohol on prostate-specific antigen (PSA) levels and prostate cancer risk. Two thousand four hundred PSA detected prostate cancer cases and 12,700 controls matched on age and general practice were identified through a case-control study nested in the PSA-testing phase of a large UK-based randomized controlled trial for prostate cancer treatment (ProtecT). Linear and multinomial logistic regression models were used to estimate ratios of geometric means (RGMs) of PSA and relative risk ratios (RRRs) of prostate cancer by stage and grade, with 95% confidence intervals (CIs), associated with weekly alcohol intake and drinking patterns. We found evidence of lower PSA (RGM 0.98, 95% CI: 0.98–0.99) and decreased risk of low Gleason-grade (RRR 0.96; 95%CI 0.93–0.99) but increased risk of high-grade prostate cancer (RRR 1.04; 95%CI 0.99–1.08; pdifference=0.004) per 10 units/week increase in alcohol consumption, not explained by current BMI, blood pressure, comorbidities, or reverse causation. This is the first large population-based study to find evidence of lower PSA levels for increasing alcohol consumption, with potential public health implications for the detection of prostate cancer. Our results also support a modestly higher risk of high-grade disease for heavy drinkers, but require independent replication to establish the nature of the association of alcohol with low-grade disease, preferably in cohorts with a heterogeneous case-mix.
Alcohol is not an established risk factor for prostate cancer; however, the current work suggests that heavy drinking could cause a small increase in risk of the more aggressive forms. If the results are confirmed to be causal, prostate cancer risk will be added to the many long-term health risks of heavy drinking, and public health strategies will then also reduce high-risk, poorer prognosis prostate cancer. The authors also found that heavy drinkers have lower PSA levels, suggesting that heavy alcohol consumption could be used as a marker to identify men in whom some cancers might be missed.
alcohol; prostate cancer; prostate specific antigen; ProtecT, nested case–control
Disturbed folate metabolism is associated with an increased risk of some cancers. Our objective was to determine whether blood levels of folate, vitamin B12 and related metabolites were associated with prostate cancer risk.
Matched case-control study nested within the UK population-based ProtecT study of PSA-detected prostate cancer in men aged 50–69 years. Plasma concentrations of folate, B12 (cobalamin), holo-haptocorrin, holo- and total-transcobalamin, and total homocysteine (tHcy) were measured in 1,461 cases and 1,507 controls. ProtecT study estimates for associations of folate, B12, and tHcy with prostate cancer risk were included in a meta-analysis, based on a systematic review.
In the ProtecT study, increased B12 and holo-haptocorrin concentrations showed positive associations with prostate cancer risk (highest vs lowest quartile of B12 odds ratio (OR)=1.17 (95% CI 0.95–1.43), P-for-trend=0.06; highest vs lowest quartile of holo-haptocorrin OR=1.27 (1.04–1.56), P-for-trend=0.01); folate, holo-transcobalamin and tHcy were not associated with prostate cancer risk. In the meta-analysis, circulating B12 levels were associated with an increased prostate cancer risk (pooled OR=1.10 (1.01–1.19) per 100 pmol/L increase in B12, 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).
Vitamin B12 and (in cohort studies) folate were associated with increased prostate cancer risk.
Given current controversies over mandatory fortification, further research is needed to determine whether these are causal associations.
folate; vitamin B12; cobalamin; transcobalamin; haptocorrin; homocysteine; folate-mediated one-carbon metabolism; prostate cancer
Mean telomere length (TL) in blood cells is heritable and has been reported to be associated with risks of several diseases, including cancer. We conducted a meta-analysis of three GWAS for TL (total n=2240) and selected 1629 variants for replication via the “iCOGS” custom genotyping array. All ∼200 000 iCOGS variants were analysed with TL, and those displaying associations in healthy controls (n = 15 065) were further tested in breast cancer cases (n = 11 024). We found a novel TL association (Ptrend < 4 × 10−10) at 3p14.4 close to PXK and evidence (Ptrend < 7 × 10−7) for TL loci at 6p22.1 (ZNF311) and 20q11.2 (BCL2L1). We additionally confirmed (Ptrend < 5 × 10−14) the previously reported loci at 3q26.2 (TERC), 5p15.3 (TERT) and 10q24.3 (OBFC1) and found supportive evidence (Ptrend < 5 × 10−4) for the published loci at 2p16.2 (ACYP2), 4q32.2 (NAF1) and 20q13.3 (RTEL1). SNPs tagging these loci explain TL differences of up to 731 bp (corresponding to 18% of total TL in healthy individuals), however, they display little direct evidence for association with breast, ovarian or prostate cancer risks.
There have been few genome-wide association studies (GWAS) of prostate cancer among diverse populations. To search for novel prostate cancer risk variants, we conducted GWAS of prostate cancer in Japanese and Latinos. In addition, we tested prostate cancer risk variants and developed genetic risk models of prostate cancer for Japanese and Latinos.
Our first stage GWAS of prostate cancer included Japanese (cases/controls=1,033/1,042) and Latino (cases/controls=1,043/1,057) from the Multiethnic Cohort. Significant associations from stage 1 (P < 1.0×10−4) were examined in silico in GWAS of prostate cancer (stage 2) in Japanese (cases/controls=1,583/3,386) and Europeans (cases/controls=1,854/1,894).
No novel stage 1 SNPs outside of known risk regions reached genome-wide significance. For Japanese, in stage 1, the most notable putative novel association was seen with 10 SNPs (P<8.0. x10−6) at chromosome 2q33; however, this was not replicated in stage 2. For Latinos, the most significant association was observed with rs17023900 at the known 3p12 risk locus (stage 1: OR=1.45; P=7.01×10−5 and stage 2: OR=1.58; P =3.05×10−7). The majority of the established risk variants for prostate cancer, 79% and 88%, were positively associated with prostate cancer in Japanese and Latinos (stage I), respectively. The cumulative effects of these variants significantly influence prostate cancer risk (OR per allele=1.10; P = 2.71×10−25 and OR=1.07; P = 1.02×10−16 for Japanese and Latinos, respectively).
Conclusion and Impact
Our GWAS of prostate cancer did not identify novel genome-wide significant variants. However, our findings demonstrate that established risk variants for prostate cancer significantly contribute to risk among Japanese and Latinos.
Associations between single nucleotide polymorphisms (SNPs) at 5p15 and multiple cancer types have been reported. We have previously shown evidence for a strong association between prostate cancer (PrCa) risk and rs2242652 at 5p15, intronic in the telomerase reverse transcriptase (TERT) gene that encodes TERT. To comprehensively evaluate the association between genetic variation across this region and PrCa, we performed a fine-mapping analysis by genotyping 134 SNPs using a custom Illumina iSelect array or Sequenom MassArray iPlex, followed by imputation of 1094 SNPs in 22 301 PrCa cases and 22 320 controls in The PRACTICAL consortium. Multiple stepwise logistic regression analysis identified four signals in the promoter or intronic regions of TERT that independently associated with PrCa risk. Gene expression analysis of normal prostate tissue showed evidence that SNPs within one of these regions also associated with TERT expression, providing a potential mechanism for predisposition to disease.
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. In order 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 SNPs at six loci: 5p15.33 (rs2736098), 10q11 (rs10993994), 10q26 (rs10788160), 12q24 (rs11067228), 17q12 (rs4430796), and 19q13.33 (rs17632542 (KLK3: I179T), each with Pcombined < 3×10−10. Among 3,834 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 (OR between 1.15 and 1.27). Assessment of association between the 6 loci and prostate cancer risk in 5,325 cases and 41,417 controls from Iceland, the Netherlands, Spain, Romania, and the US showed that the SNPs at 10q26 and 12q24 were exclusively associated with PSA levels, whereas the other 4 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.
To identify new risk variants for cutaneous basal cell carcinoma, we performed a genome-wide association study of 16 million SNPs identified through whole-genome sequencing of 457 Icelanders. We imputed genotypes for 41,675 Illumina SNP chip-typed Icelanders and their relatives. In the discovery phase, the strongest signal came from rs78378222[C] (odds ratio (OR) = 2.36, P = 5.2 × 10−17), which has a frequency of 0.0192 in the Icelandic population. We then confirmed this association in non-Icelandic samples (OR = 1.75, P = 0.0060; overall OR = 2.16, P = 2.2 × 10−20). rs78378222 is in the 3′ untranslated region of TP53 and changes the AATAAA polyadenylation signal to AATACA, resulting in impaired 3′-end processing of TP53 mRNA. Investigation of other tumor types identified associations of this SNP with prostate cancer (OR = 1.44, P = 2.4 × 10−6), glioma (OR = 2.35, P = 1.0 × 10−5) and colorectal adenoma (OR = 1.39, P = 1.6 × 10−4). However, we observed no effect for breast cancer, a common Li-Fraumeni syndrome tumor (OR = 1.06, P = 0.57, 95% confidence interval 0.88–1.27).
Prostate cancer (PrCa) is the most common non-skin cancer diagnosed among males in developed countries and the second leading cause of cancer mortality, yet little is known regarding its etiology and factors that influence clinical outcome. Genome-wide association studies (GWAS) of PrCa have identified at least 30 distinct loci associated with small differences in risk. We conducted a GWAS in 2782 advanced PrCa cases (Gleason grade ≥ 8 or tumor stage C/D) and 4458 controls with 571 243 single nucleotide polymorphisms (SNPs). Based on in silico replication of 4679 SNPs (Stage 1, P < 0.02) in two published GWAS with 7358 PrCa cases and 6732 controls, we identified a new susceptibility locus associated with overall PrCa risk at 2q37.3 (rs2292884, P= 4.3 × 10−8). We also confirmed a locus suggested by an earlier GWAS at 12q13 (rs902774, P= 8.6 × 10−9). The estimated per-allele odds ratios for these loci (1.14 for rs2292884 and 1.17 for rs902774) did not differ between advanced and non-advanced PrCa (case-only test for heterogeneity P= 0.72 and P= 0.61, respectively). Further studies will be needed to assess whether these or other loci are differentially associated with PrCa subtypes.
Prostate cancer (PrCa) is the most frequently diagnosed male cancer in developed countries. To identify common PrCa susceptibility alleles, we conducted a multi-stage genome-wide association study and previously reported the results of the first two stages, which identified 16 novel susceptibility loci for PrCa. Here we report the results of stage 3 in which we evaluated 1,536 SNPs in 4,574 cases and 4,164 controls. Ten novel association signals were followed up through genotyping in 51,311 samples in 30 studies through the international PRACTICAL consortium. In addition to previously reported loci, we identified a further seven new prostate cancer susceptibility loci on chromosomes 2p, 3q, 5p, 6p, 12q and Xq (P=4.0 ×10−8 to P=2.7 ×10−24). We also identified a SNP in TERT more strongly associated with PrCa than that previously reported. More than 40 PrCa susceptibility loci, explaining ~25% of the familial risk in this disease, have now been identified.