Association analysis of 9,560 prostate cancer cases from the International Consortium of Prostate Cancer Genetics confirms the role of reported prostate cancer associated SNPs for familial disease

Impact of Family History and Germline Genetic Risk Single Nucleotide Polymorphisms on Long-Term Outcomes of Favorable-Risk Prostate Cancer

PURPOSE

Family history and germline genetic risk single nucleotide polymorphisms (SNPs) have been separately shown to stratify lifetime risk of prostate cancer. Here, we evaluate the combined prognostic value of family history of prostate and other related cancers and germline risk SNPs among patients with favorable-risk prostate cancer.

MATERIALS AND METHODS

A total of 1367 participants from the prospective Health Professionals Follow-up Study diagnosed with low- or favorable intermediate-risk prostate cancer from 1986 to 2017 underwent genome-wide SNP genotyping. Multivariable Cox regression was used to estimate the association between family history, specific germline risk variants, and a 269 SNP polygenic risk score with prostate cancer‒specific death.

RESULTS

Family history of prostate, breast, and/or pancreatic cancer was observed in 489 (36%) participants. With median follow-up from diagnosis of 14.9 years, participants with favorable-risk prostate cancer with a positive family history had a significantly higher risk of prostate cancer‒specific death (HR 1.95, 95% CI 1.15-3.32, P = .014) compared to those without any family history. The rs2735839 (19q13) risk allele was associated with prostate cancer‒specific death (HR 1.81 per risk allele, 95% CI 1.04-3.17, P = .037), whereas the polygenic risk score was not. Combined family history and rs2735839 risk allele were each associated with an additive risk of prostate cancer‒specific death (HR 1.78 per risk factor, 95% CI 1.25-2.53, P = .001).

CONCLUSIONS

Family history of prostate, breast, or pancreatic cancer and/or a 19q13 germline risk allele are associated with an elevated risk of prostate cancer‒specific death among favorable-risk patients. These findings have implications for how family history and germline genetic risk SNPs should be factored into clinical decision-making around favorable-risk prostate cancer.

Two-stage Study of Familial Prostate Cancer by Whole-exome Sequencing and Custom Capture Identifies 10 Novel Genes Associated with the Risk of Prostate Cancer

BACKGROUND

Family history of prostate cancer (PCa) is a well-known risk factor, and both common and rare genetic variants are associated with the disease.

OBJECTIVE

To detect new genetic variants associated with PCa, capitalizing on the role of family history and more aggressive PCa.

DESIGN, SETTING, AND PARTICIPANTS

A two-stage design was used. In stage one, whole-exome sequencing was used to identify potential risk alleles among affected men with a strong family history of disease or with more aggressive disease (491 cases and 429 controls). Aggressive disease was based on a sum of scores for Gleason score, node status, metastasis, tumor stage, prostate-specific antigen at diagnosis, systemic recurrence, and time to PCa death. Genes identified in stage one were screened in stage two using a custom-capture design in an independent set of 2917 cases and 1899 controls.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Frequencies of genetic variants (singly or jointly in a gene) were compared between cases and controls.

RESULTS AND LIMITATIONS

Eleven genes previously reported to be associated with PCa were detected (ATM, BRCA2, HOXB13, FAM111A, EMSY, HNF1B, KLK3, MSMB, PCAT1, PRSS3, and TERT), as well as an additional 10 novel genes (PABPC1, QK1, FAM114A1, MUC6, MYCBP2, RAPGEF4, RNASEH2B, ULK4, XPO7, and THAP3). Of these 10 novel genes, all but PABPC1 and ULK4 were primarily associated with the risk of aggressive PCa.

CONCLUSIONS

Our approach demonstrates the advantage of gene sequencing in the search for genetic variants associated with PCa and the benefits of sampling patients with a strong family history of disease or an aggressive form of disease.

PATIENT SUMMARY

Multiple genes are associated with prostate cancer (PCa) among men with a strong family history of this disease or among men with an aggressive form of PCa.

Rare germline genetic variants and risk of aggressive prostate cancer

Few genetic risk factors have been demonstrated to be specifically associated with aggressive prostate cancer (PrCa). Here, we report a case-case study of PrCa comparing the prevalence of germline pathogenic/likely pathogenic (P/LP) genetic variants in 787 men with aggressive disease and 769 with nonaggressive disease. Overall, we observed P/LP variants in 11.4% of men with aggressive PrCa and 9.8% of men with nonaggressive PrCa (two-tailed Fisher's exact tests, P = .28). The proportion of BRCA2 and ATM P/LP variant carriers in men with aggressive PrCa exceeded that observed in men with nonaggressive PrCa; 18/787 carriers (2.3%) and 4/769 carriers (0.5%), P = .004, and 14/787 carriers (0.02%) and 5/769 carriers (0.01%), P = .06, respectively. Our findings contribute to the extensive international effort to interpret the genetic variation identified in genes included on gene-panel tests, for which there is currently an insufficient evidence-base for clinical translation in the context of PrCa risk.

Aggressive prostate cancer phenotype and genome-wide association studies: where are we now?

The majority of prostate cancer (PCa) is indolent, however, a percentage of patients are initially diagnosed with metastatic disease, for which there is a worse prognosis. There is a lack of biomarkers to identify men at greater risk for developing aggressive PCa. Genome-wide association studies (GWAS) scan the genome to search associations of SNPs with specific traits, like cancer. To date, eight GWAS have resulted in the reporting of 16 SNPs associated with aggressive PCa (p < 5.00 × 10^-2). Still, validation studies need to be conducted to confirm the obtained results as GWAS can generate false-positive results. Furthermore, post-GWAS studies provide a better understanding of the functional consequences.

Inflammatory Bowel Disease and the Risk of Prostate Cancer

BACKGROUND

There are limited data examining the risk of prostate cancer (PCa) in patients with inflammatory bowel disease (IBD).

OBJECTIVE

To compare the incidence of PCa between men with and those without IBD.

DESIGN, SETTING, AND PARTICIPANTS

This was a retrospective, matched-cohort study involving a single academic medical center and conducted from 1996 to 2017. Male patients with IBD (cases=1033) were randomly matched 1:9 by age and race to men without IBD (controls=9306). All patients had undergone at least one prostate-specific antigen (PSA) screening test.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Kaplan-Meier and multivariable Cox proportional hazard models, stratified by age and race, evaluated the relationship between IBD and the incidence of any PCa and clinically significant PCa (Gleason grade group ≥2). A mixed-effect regression model assessed the association of IBD with PSA level.

RESULTS AND LIMITATIONS

PCa incidence at 10yr was 4.4% among men with IBD and 0.65% among controls (hazard ratio [HR] 4.84 [3.34-7.02] [3.19-6.69], p<0.001). Clinically significant PCa incidence at 10yr was 2.4% for men with IBD and 0.42% for controls (HR 4.04 [2.52-6.48], p<0.001). After approximately age 60, PSA values were higher among patients with IBD (fixed-effect interaction of age and patient group: p=0.004). Results are limited by the retrospective nature of the analysis and lack of external validity.

CONCLUSIONS

Men with IBD had higher rates of clinically significant PCa when compared with age- and race-matched controls.

PATIENT SUMMARY

This study of over 10000 men treated at a large medical center suggests that men with inflammatory bowel disease may be at a higher risk of prostate cancer than the general population.

Admixture Mapping Links RACGAP1 Regulation to Prostate Cancer in African Americans

BACKGROUND/AIM

Prostate cancer is the most common malignancy in US males. African American men have higher incidence and mortality rates than European Americans. Five single nucleotide polymorphisms are associated with PCa. We hypothesized haplotypes inferred from these SNPs are also associated with PCa.

PATIENTS AND METHODS

We genotyped SNPs in a case-control admixture mapping study. SNP haplotypes inferred for 157 PCa cases and 150 controls were used in the regression analysis.

RESULTS

We found an association between "GTCCC", "ATTCT", and "ACCCC" haplotypes and PCa after ancestry adjustment (OR=3.62, 95%CI=1.42-9.21, p=0.0070; OR=7.89, 95%CI=2.36-26.31, p=0.0008; OR=4.34, 95%CI=1.75-10.78, p=0.0016). The rs615382 variant disrupts the recombination signal binding protein with immunoglobulin kappa J binding site in Rac GTPase activating protein 1 (RACGAP1).

CONCLUSION

Disruption of notch 1 mediated-repression of RACGAP1 may contribute to PCa in African Americans.

Rare germline mutations in African American men diagnosed with early-onset prostate cancer

BACKGROUND

African Americans have both a higher incidence of prostate cancer and greater disease-specific mortality compared with non-Hispanic whites. Historically, the investigation of the contribution of rare genetic variants to prostate cancer in African American men has been hampered by low participation in large genetic studies, particularly those focused on early-onset and familial disease.

METHODS

We sequenced 160 genes purported to be involved in carcinogenic pathways in germline DNA samples collected from 96 African American men diagnosed with early-onset prostate cancer (≤55 years at diagnosis). REVEL software was used to determine the pathogenic potential of observed missense variants.

RESULTS

We observed three protein-truncating mutations, one in BRCA2 and two in BRIP1 in three African American men diagnosed with early-onset prostate cancer. Furthermore, we observed five rare, mostly private, missense variants among four genes (BRCA1, BRCA2, PMS2, and ATM) that were predicted to be deleterious and hence likely pathogenic in our patient sample.

CONCLUSIONS

Protein-truncating mutations in BRCA2 and BRIP1 were discovered in African American men diagnosed with early-onset prostate cancer. Further study is necessary to determine the role of rare, missense variants to prostate cancer incidence, and progression in this group of high-risk men.

Systematic identification of functionally relevant risk alleles to stratify aggressive versus indolent prostate cancer

Novel approaches for classification, including molecular features, are needed to direct therapy for men with low-grade prostate cancer (PCa), especially men on active surveillance. Risk alleles identified from genome-wide association studies (GWAS) could improve prognostication. Those risk alleles that coincided with genes and somatic copy number aberrations associated with progression of PCa were selected as the most relevant for prognostication.

In a systematic literature review, a total of 698 studies were collated. Fifty-three unique SNPs residing in 29 genomic regions, including 8q24, 10q11 and 19q13, were associated with PCa progression. Functional studies implicated 21 of these single nucleotide polymorphisms (SNPs) as modulating the expression of genes in the androgen receptor pathway and several other oncogenes. In particular, 8q24, encompassing MYC, harbours a high density of SNPs conferring unfavourable pathological characteristics in low-grade PCa, while a copy number gain of MYC in low-grade PCa was associated with prostate-specific antigen recurrence after radical prostatectomy.

By combining GWAS data with gene expression and structural rearrangements, risk alleles were identified that could provide a new basis for developing a prognostication tool to guide therapy for men with early prostate cancer.

Association between polymorphisms in TP53 and MDM2 genes and susceptibility to prostate cancer

Tumor protein 53 (TP53), a tumor suppressor gene, is a vital cellular cancer suppressor in multicellular organisms. Murine double minute-2 (MDM2) is an oncoprotein that inhibits TP53 activity. A number of studies have examined the association of TP53 and MDM2 polymorphisms with the risk of common forms of cancer, but the findings remain inconclusive. The present study aimed to evaluate the impact of the 40-bp insertion/deletion (I/D) polymorphism (rs3730485) in the MDM2 promoter region and the 16-bp I/D polymorphism (rs17878362) in TP53 on the susceptibility of prostate cancer (PCa) in a sample of the Iranian population. This case-control study included 103 patients with pathologically confirmed PCa and 142 patients with benign prostatic hyperplasia. The MDM2 40-bp I/D and TP53 16-bp I/D polymorphism was determined using polymerase chain reaction analysis. The results demonstrated that the MDM2 40-bp I/D polymorphism increased the risk of PCa in a co-dominant inheritance model [odds ratio (OR)=1.88; 95% confidence interval (CI)=1.11-3.19; P=0.023, D/D vs. I/I], while this variant marginally increased the risk of PCa in a dominant model (OR=1.69; 95% CI=1.00-2.83; P=0.051, I/D+D/D vs. I/I). No significant association was observed between the TP53 16-bp I/D polymorphism and PCa. In conclusion, the present study demonstrated that the 40-bp I/D polymorphism in the MDM2 promoter increased the risk of PCa in an Iranian population. Further investigations with diverse ethnicities and larger sample sizes are required to verify these results.

Inherited Predisposition to Prostate Cancer: From Gene Discovery to Clinical Impact

Family history of prostate cancer is one of the three most important risk factors for the disease in addition to age and race. Yet despite the recognition of this significant heritable component, it has been challenging to identify the genes associated with prostate cancer predisposition. Initial approaches focused on the collection of multiplex prostate cancer families. However, despite more than 20 years of linkage studies, few genes have been identified that account for a significant number of hereditary prostate cancer families. Our research team studied a large number of families with linkage evidence to chromosome 17q21-22 and ultimately identified a recurrent mutation in the HOXB13 gene. The HOXB13 G84E mutation occurs on a common haplotype consistent with a founder allele and worldwide, this allele accounts for ~5% of hereditary prostate cancer families. Current research from us and others focuses on the use of whole exome sequencing to identify rare cancer-causing alleles in early-onset and/or metastatic prostate cancer cases. The recent recognition of both germline and somatic alterations in DNA repair genes is important because mutation carriers appear to have a significant likelihood of developing aggressive/metastatic cancer.

PRECISION MANAGEMENT OF LOCALIZED PROSTATE CANCER

INTRODUCTION

The vast majority of men who are diagnosed with prostate cancer die of other causes, highlighting the importance of determining which patient has a risk of death from prostate cancer. Precision management of prostate cancer patients includes distinguishing which men have potentially lethal disease and employing strategies for determining which treatment modality appropriately balances the desire to achieve a durable response while preventing unnecessary overtreatment.

AREAS COVERED

In this review, we highlight precision approaches to risk assessment and a context for the precision-guided application of definitive therapy. We focus on three dilemmas relevant to the diagnosis of localized prostate cancer: screening, the decision to treat, and postoperative management.

EXPERT COMMENTARY

In the last five years, numerous precision tools have emerged with potential benefit to the patient. However, to achieve optimal outcome, the decision to employ one or more of these tests must be considered in the context of prevailing conventional factors. Moreover, performance and interpretation of a molecular or imaging precision test remains practitioner-dependent. The next five years will witness increased marriage of molecular and imaging biomarkers for improved multi-modal diagnosis and discrimination of disease that is aggressive versus truly indolent.

Mapping Complex Traits in a Diversity Outbred F1 Mouse Population Identifies Germline Modifiers of Metastasis in Human Prostate Cancer

It is unclear how standing genetic variation affects the prognosis of prostate cancer patients. To provide one controlled answer to this problem, we crossed a dominant, penetrant mouse model of prostate cancer to Diversity Outbred mice, a collection of animals that carries over 40 million SNPs. Integration of disease phenotype and SNP variation data in 493 F1 males identified a metastasis modifier locus on Chromosome 8 (LOD = 8.42); further analysis identified the genes Rwdd4, Cenpu, and Casp3 as functional effectors of this locus. Accordingly, analysis of over 5,300 prostate cancer patient samples revealed correlations between the presence of genetic variants at these loci, their expression levels, cancer aggressiveness, and patient survival. We also observed that ectopic overexpression of RWDD4 and CENPU increased the aggressiveness of two human prostate cancer cell lines. In aggregate, our approach demonstrates how well-characterized genetic variation in mice can be harnessed in conjunction with systems genetics approaches to identify and characterize germline modifiers of human disease processes.

Role of Genetic Polymorphisms in the Development and Prognosis of Sporadic and Familial Prostate Cancer

Backgrounds

Our aim was to evaluate the role of 20 genetic polymorphisms in the development and prognosis of sporadic and familial PC. A case-control study of 185 patients who underwent radical prostatectomy from 1997 to 2011. These patients were divided into two groups based on their family history. Gleason grade, PSA value and pathological TNM 2002 stage were used as prognostic factors. Blood samples from 70 men without PC were used as controls. The SNPs were genotyped using a TaqMan^® SNP Genotyping Assay Kit.

Results

Considering susceptibility, the polymorphic allele in the SNP rs2660753 on chromosome 3 was significantly more prevalent in controls (p = 0.01). For familial clustering, the polymorphic homozygote genotype of the SNP rs7931342 was five times more frequent in patients with familial PC compared to sporadic PC (p = 0.01). Regarding the SNP 1447295, the polymorphic homozygote genotype was more prevalent in patients with organ-confined PC (p = 0.05), and most importantly, the polymorphic allele occurred more frequently in patients without biochemical recurrence (p = 0.01). Kaplan-Meier analysis showed a median biochemical recurrence free survival of 124.2 compared to 85.6 months for patients with the wild-type allele (p = 0.007).

Conclusion

Our findings provide the evidence for the association of 20 recently highlighted SNPs and their susceptibility, familial clustering, staging, Gleason score and biochemical recurrence of PC. We believe that the association between these SNPs and PC may contribute to the development of alternative tools that can facilitate the early detection and prognosis of this disease.

Defining the Influence of Germline Variation on Metastasis Using Systems Genetics Approaches

Cancer is estimated to be responsible for 8 million deaths worldwide and over half a million deaths every year in the United States. The majority of cancer-related deaths in solid tumors is directly associated with the effects of metastasis. While the influence of germline factors on cancer risk and development has long been recognized, the contribution of hereditary variation to tumor progression and metastasis has only gained acceptance more recently. A variety of approaches have been used to define how hereditary variation influences tumor progression and metastasis. One approach that garnered much early attention was epidemiological studies of cohorts of cancer patients, which demonstrated that specific loci within the human genome are associated with a differential propensity for aggressive tumor development. However, a powerful, and somewhat underutilized approach has been the use of systems genetics approaches in transgenic mouse models of human cancer. Such approaches are typically multifaceted, and involve integration of multiple lines of evidence derived, for example, from genetic and transcriptomic screens of genetically diverse mouse models of cancer, coupled with bioinformatics analysis of human cancer datasets, and functional analysis of candidate genes. These methodologies have allowed for the identification of multiple hereditary metastasis susceptibility genes, with wide-ranging cellular functions including regulation of gene transcription, cell proliferation, and cell-cell adhesion. In this chapter, we review how each of these approaches have facilitated the identification of these hereditary metastasis modifiers, the molecular functions of these metastasis-associated genes, and the implications of these findings upon patient survival.

The clinical phenotype of hereditary versus sporadic prostate cancer: HPC definition revisited

BACKGROUND

The definition of hereditary prostate cancer (HPC) is based on family history and age at onset. Intuitively, HPC is a serious subtype of prostate cancer but there are only limited data on the clinical phenotype of HPC. Here, we aimed to compare the prognosis of HPC to the sporadic form of prostate cancer (SPC).

METHODS

HPC patients were identified through a national registry of HPC families in the Netherlands, selecting patients diagnosed from the year 2000 onward (n = 324). SPC patients were identified from the Netherlands Cancer Registry (NCR) between 2003 and 2006 for a population-based study into the genetic susceptibility of PC (n = 1,664). Detailed clinical data were collected by NCR-registrars, using a standardized registration form. Follow-up extended up to the end of 2013. Differences between the groups were evaluated by cross-tabulations and tested for statistical significance while accounting for familial dependency of observations by GEE. Differences in progression-free and overall survival were evaluated using χ(2) testing with GEE in a proportional-hazards model.

RESULTS

HPC patients were on average 3 years younger at diagnosis, had lower PSA values, lower Gleason scores, and more often locally confined disease. Of the HPC patients, 35% had high-risk disease (NICE-criteria) versus 51% of the SPC patients. HPC patients were less often treated with active surveillance. Kaplan-Meier 5-year progression-free survival after radical prostatectomy was comparable for HPC (78%) and SPC (74%; P = 0.30). The 5-year overall survival was 85% (95%CI 81-89%) for HPC versus 80% (95%CI 78-82%) for SPC (P = 0.03).

CONCLUSIONS

HPC has a favorable clinical phenotype but patients more often underwent radical treatment. The major limitation of HPC is the absence of a genetics-based definition of HPC, which may lead to over-diagnosis of PC in men with a family history of prostate cancer. The HPC definition should, therefore, be re-evaluated, aiming at a reduction of over-diagnosis and overtreatment among men with multiple relatives diagnosed with PC. Prostate 76:897-904, 2016. © 2016 The Authors. The Prostate published by Wiley Periodicals, Inc.

The PROFILE Feasibility Study: Targeted Screening of Men With a Family History of Prostate Cancer

BACKGROUND

A better assessment of individualized prostate cancer (PrCa) risk is needed to improve screening. The use of the prostate-specific antigen (PSA) level for screening in the general population has limitations and is not currently advocated. Approximately 100 common single nucleotide polymorphisms (SNPs) have been identified that are associated with the risk of developing PrCa. The PROFILE pilot study explored the feasibility of using SNP profiling in men with a family history (FH) of PrCa to investigate the probability of detecting PrCa at prostate biopsy (PB). The primary aim of this pilot study was to determine the safety and feasibility of PrCa screening using transrectal ultrasound-guided PB with or without diffusion-weighted magnetic resonance imaging (DW-MRI) in men with a FH. A secondary aim was to evaluate the potential use of SNP profiling as a screening tool in this population.

PATIENTS AND METHODS

A total of 100 men aged 40-69 years with a FH of PrCa underwent PB, regardless of their baseline PSA level. Polygenic risk scores (PRSs) were calculated for each participant using 71 common PrCa susceptibility alleles. We treated the disease outcome at PB as the outcome variable and evaluated its associations with the PRS, PSA level, and DW-MRI findings using univariate logistic regression.

RESULTS

Of the 100 men, 25 were diagnosed with PrCa, of whom 12 (48%) had clinically significant disease. Four adverse events occurred and no deaths. The PSA level and age at study entry were associated with PrCa at PB (p = .00037 and p = .00004, respectively).

CONCLUSION

The results of the present pilot study have demonstrated that PB is a feasible and safe method of PrCa screening in men with a FH, with a high proportion of PrCa identified requiring radical treatment. It is feasible to collect data on PrCa-risk SNPs to evaluate their combined effect as a potential screening tool. A larger prospective study powered to detect statistical associations is in progress.

IMPLICATIONS FOR PRACTICE

Prostate biopsy is a feasible and safe approach to prostate cancer screening in men with a family history and detects a high proportion of prostate cancer that needs radical treatment. Calculating a polygenic risk score using prostate cancer risk single nucleotide polymorphisms could be a potential future screening tool for prostate cancer.

An examination of clinical differences between carriers and non-carriers of chromosome 8q24 risk alleles in a New Zealand Caucasian population with prostate cancer

Background. Prostate cancer makes up approximately 15% of all cancers diagnosed in men in developed nations and approximately 4% of cases in developing nations. Although it is clear that prostate cancer has a genetic component and single nucleotide polymorphisms (SNPs) can contribute to prostate cancer risk, detecting associations is difficult in multi-factorial diseases, as environmental and lifestyle factors also play a role. In this study, specific clinical characteristics, environmental factors and genetic risk factors were assessed for interaction with prostate cancer.

Methods. A total of 489 prostate cancer cases and 427 healthy controls were genotyped for SNPs found on chromosome 8q24 and a genetic risk score was calculated. In addition the SNPs were tested for an association with a number of clinical and environmental factors.

Results. Age and tobacco use were positively associated, whilst alcohol consumption was negatively associated with prostate cancer risk. The following SNPs found on chromosome 8q24 were statistically significantly associated with prostate cancer: rs10086908, rs16901979; rs1447295and rs4242382. No association between Gleason score and smoking status, or between Gleason score and genotype were detected.

Conclusion. A genetic risk score was calculated based on the 15 SNPs tested and found to be significantly associated with prostate cancer risk. Smoking significantly contributed to the risk of developing prostate cancer, and this risk was further increased by the presence of four SNPs in the 8q24 chromosomal region.

Known susceptibility SNPs for sporadic prostate cancer show a similar association with "hereditary" prostate cancer

BACKGROUND

More than 70 single nucleotide polymorphisms (SNPs) have been reported to be associated with prostate cancer (PC) risk; these were mainly identified in the general population with predominantly sporadic PC (SPC). Previous studies have suggested similar associations between a selection of these SNPs and hereditary PC (HPC). Our aim was to evaluate the effect of all known PC risk SNPs and their discriminative value for SPC and HPC.

METHODS

Seventy-four PC susceptibility SNPs (reported in literature up to June 2014) were genotyped in a population-based series of 620 SPC patients, 312 HPC patients from the national Dutch registry and 1819 population-based referents. Association analyses were performed using logistic regression, focusing on directional consistency of the odds ratios (ORs) with those in the original reports, that is, whether the OR was in the same direction as in the original report. Discriminative performance was evaluated by a genetic risk score used in logistic regression and receiver operating characteristic (ROC) curve analyses.

RESULTS

Directional consistency was seen for 62 SNPs in SPC and 64 SNPs in HPC, 56 of which overlapped. ORs were mostly higher for HPC with 22 ORs >1.25 versus 5 for SPC. Discriminative performance was better for HPC with an area under the ROC curve of 0.73 versus 0.64 for SPC.

CONCLUSIONS

A large overlap was found for the associations between low-penetrance susceptibility SNPs and SPC and HPC, suggesting a similarity in genetic etiology. This warrants a reconsideration of "HPC" and a restrictive policy toward prostate-specific antigen testing in men with a positive family history. Genetic risk scores might be used for PC risk stratification on the population level.

The clinic-pathological characteristics of prostate cancer in an Irish subpopulation with a serum PSA less than 4.0ng/ml

Background:

Prostate specific antigen (PSA) has been used as a biomarker for prostate cancer for the last 20 years. Traditionally, a serum PSA <4 ng/ml has been used as a general cut-off between normal and abnormal readings. There is evidence to demonstrate that men with a normal serum PSA can develop prostate cancer. The aim of this study was to investigate the clinico-pathological features of prostate cancer in a non-screened Irish cohort with serum PSA <4 ng/ml.

Methods:

A retrospective analysis was performed of all patients who underwent radical retropubic prostatectomy (RRP) in a tertiary referral unit over a 10-year period (2000–2010). Clinico-pathological characteristics were collated including those from trans-rectal ultrasound-guided (TRUS) prostate biopsies and radical prostatectomy specimens.

Results:

Between 2000 and 2010, 651 men underwent an RRP, with 43 (6.6%) having a serum PSA <4 ng/ml. The median PSA was 3.2 ng/ml (range 0.8–4.0). Nineteen (44.2%) had palpable disease on direct rectal examination (DRE). Following prostatectomy, 28 (65.12%) had Gleason 6 disease, 14 (32.56%) had Gleason 7 disease and one (2.32%) had Gleason 8 disease. Five (11.63%) patients were upgraded from TRUS biopsy to final histopathology. Six (13.95%) patients had pathological evidence of extracapsular extension on final pathology. Three (6.98%) patients experienced biochemical recurrence and received salvage radiation therapy after a median time of 24 months. The median follow-up was 106 months (range 36–158). Twenty (46.51%) patients had a first-degree family history of prostate cancer.

Conclusions:

A PSA cut-off of 4 ng/ml has commonly been used in the detection of prostate cancer. Our study emphasizes that this cut-off is inappropriate and that no specific level of PSA can be used. Management decisions need to be individualized based on index of suspicion with concomitant counselling and rectal examination.

Dysregulation of the homeobox transcription factor gene HOXB13: role in prostate cancer

Prostate cancer (PC) is the most common noncutaneous cancer in men, and epidemiological studies suggest that about 40% of PC risk is heritable. Linkage analyses in hereditary PC families have identified multiple putative loci. However, until recently, identification of specific risk alleles has proven elusive. Cooney et al used linkage mapping and segregation analysis to identify a putative risk locus on chromosome 17q21-22. In search of causative variant(s) in genes from the candidate region, a novel, potentially deleterious G84E substitution in homeobox transcription factor gene HOXB13 was observed in multiple hereditary PC families. In follow-up testing, the G84E allele was enriched in cases, especially those with an early diagnosis or positive family history of disease. This finding was replicated by others, confirming HOXB13 as a PC risk gene. The HOXB13 protein plays diverse biological roles in embryonic development and terminally differentiated tissue. In tumor cell lines, HOXB13 participates in a number of biological functions, including coactivation and localization of the androgen receptor and FOXA1. However, no consensus role has emerged and many questions remain. All HOXB13 variants with a proposed role in PC risk are predicted to damage the protein and lie in domains that are highly conserved across species. The G84E variant has the strongest epidemiological support and lies in a highly conserved MEIS protein-binding domain, which binds cofactors required for activation. On the basis of epidemiological and biological data, the G84E variant likely modulates the interaction between the HOXB13 protein and the androgen receptor, as well as affecting FOXA1-mediated transcriptional programming. However, further studies of the mutated protein are required to clarify the mechanisms by which this translates into PC risk.