HOXB13 mutation and prostate cancer: studies of siblings and aggressive disease

Germline Variants in DNA Damage Repair Genes and HOXB13 Among Black Patients With Early-Onset Prostate Cancer

PURPOSE

Genetic studies of prostate cancer susceptibility have predominantly focused on non-Hispanic White men, despite the observation that Black men are more likely to develop prostate cancer and die from the disease. Therefore, we sought to identify genetic variants in Black patients diagnosed with early-onset prostate cancer.

METHODS

Whole-exome sequencing of germline DNA from a population-based cohort of Black men diagnosed with prostate cancer at age 62 years or younger was performed. Analysis was focused on a panel of DNA damage repair (DDR) genes and HOXB13. All discovered variants were ranked according to their pathogenic potential based upon REVEL score, evidence from existing literature, and prevalence in the cohort. Logistic regression was used to investigate associations between mutation status and relevant clinical characteristics.

RESULTS

Among 743 Black prostate cancer patients, we identified 26 unique pathogenic (P) or likely pathogenic (LP) variants in 14 genes (including HOXB13, BRCA1/2, BRIP1, ATM, CHEK2, and PALB2) among 30 men, or approximately 4.0% of the patient population. We also identified 33 unique variants of unknown significance in 16 genes among 39 men. Because of the rarity of these variants in the population, most associations between clinical characteristics did not achieve statistical significance. However, our results suggest that carriers for P or LP (P/LP) variants were more likely to have a first-degree relative diagnosed with DDR gene-associated cancer, have a higher prostate-specific antigen at time of diagnosis, and be diagnosed with metastatic disease.

CONCLUSION

Variants in DDR genes and HOXB13 may be important cancer risk factors for Black men diagnosed with early-onset prostate cancer, and are more frequently observed in men with a family history of cancer.

Germline testing and genetic counselling in prostate cancer

Genetic testing for prostate cancer is rapidly growing and is increasingly being driven by precision medicine. Rates of germline pathogenic variants have been reported in up to 15% of men with prostate cancer, particularly in metastatic disease, and results of genetic testing could uncover options for precision therapy along with a spectrum of hereditary cancer-predisposition syndromes with unique clinical features that have complex management options. Thus, the pre-test discussion, whether delivered by genetic counsellors or by health-care professionals in hybrid models, involves information on hereditary cancer risk, extent of gene testing, purpose of testing, medical history and family history, potential types of results, additional cancer risks that might be uncovered, genetically based management and effect on families. Understanding precision medicine, personalized cancer risk management and syndrome-related cancer risk management is important in order to develop collaborative strategies with genetic counselling for optimal care of patients and their families.

In this Review, Russo and Giri describe and discuss germline testing criteria, genetic testing strategies, genetically informed screening, precision management, delivery of genetic counselling or alternative genetic services and special considerations for men with prostate cancer.

Germline (hereditary) genetic testing is rising in importance for treatment, screening and risk assessment of prostate cancer.

Multiple hereditary cancer syndromes might be associated with prostate cancer, might confer risk of other cancerous and non-cancerous conditions, and can have hereditary cancer implications for family members. The rates of these syndromes can vary based upon the attributed genetic mutations.

Multiple aspects of germline testing should be discussed in the pre-test setting for men to make an informed decision, including the purpose of genetic testing, the benefits and risks of testing, hereditary cancer risk, identification of additional cancer risks, familial implications and the state of genetic discrimination protections.

Genetic evaluation can be conducted by genetic counsellors or a hybrid model can be employed, in which health-care providers deliver pre-test informed consent for testing, order testing and then determine referral to genetic counselling for appropriate patients.

Precision medicine is increasingly driving decisions for germline testing. Poly(ADP-ribose) polymerase (PARP) inhibitors, immune checkpoint inhibitors and various other agents now in clinical trials have clinical activity in patients with certain hereditary cancer gene mutations, such as in DNA repair genes.

Patients’ experiences with germline testing can be variable; taking the patient’s current experience into account, considering referral to genetic counselling when needed and offering germline testing for eligible men at repeated intervals if initially declined are important.

The HOXB13 variant X285K is associated with clinical significance and early age at diagnosis in African American prostate cancer patients

BACKGROUND

Recently, a novel HOXB13 variant (X285K) was observed in men of African descent with prostate cancer (PCa) in Martinique. Little is known about this or other variants in HOXB13 which may play a role in PCa susceptibility in African-American (AA) men.

METHODS

We sequenced HOXB13 in an AA population of 1048 men undergoing surgical treatment for PCa at Johns Hopkins Hospital.

RESULTS

Seven non-synonymous germline variants were observed in the patient population. While six of these variants were seen only once, X285K was found in eight patients. In a case-case analysis, we find that carriers of this latter variant are at increased risk of clinically significant PCa (1.2% carrier rate in Gleason Score ≥7 PCa vs. 0% in Gleason Score <7 PCa, odds ratio, OR = inf; 95% Confidence Interval, 95%CI:1.05-inf, P = 0.028), as well as PCa with early age at diagnosis (2.4% carrier rate in patients <50 year vs. 0.5% carrier rate in patients ≥50 year, OR = 5.25, 95% CI:1.00-28.52, P = 0.03).

CONCLUSIONS

While this variant is rare in the AA population (~0.2% MAF), its ancestry-specific occurrence and apparent preferential association with risk for the more aggressive disease at an early age emphasizes its translational potential as an important, novel PCa susceptibility marker in the high-risk AA population.

Genetic Contributions to Prostate Cancer Disparities in Men of West African Descent

Prostate cancer (PCa) is the second most frequently diagnosed malignancy and the second leading cause of death in men worldwide, after adjusting for age. According to the International Agency for Research on Cancer, continents such as North America and Europe report higher incidence of PCa; however, mortality rates are highest among men of African ancestry in the western, southern, and central regions of Africa and the Caribbean. The American Cancer Society reports, African Americans (AAs), in the United States, have a 1.7 increased incidence and 2.4 times higher mortality rate, compared to European American's (EAs). Hence, early population history in west Africa and the subsequent African Diaspora may play an important role in understanding the global disproportionate burden of PCa shared among Africans and other men of African descent. Nonetheless, disparities involved in diagnosis, treatment, and survival of PCa patients has also been correlated to socioeconomic status, education and access to healthcare. Although recent studies suggest equal PCa treatments yield equal outcomes among patients, data illuminates an unsettling reality of disparities in treatment and care in both, developed and developing countries, especially for men of African descent. Yet, even after adjusting for the effects of the aforementioned factors; racial disparities in mortality rates remain significant. This suggests that molecular and genomic factors may account for much of PCa disparities.

Single nucleotide polymorphisms in microRNA binding sites on the HOX genes regulate carcinogenesis: An in-silico approach

Homeobox proteins, encoded by HOX genes, are transcriptional factors playing a crucial role in the master regulatory pathway in the cells. Any mutations in HOX genes will affect the expression of its allied proteins. Such mutations were correlated to the development of different cancer types. In this study, we found 15 HOX genes with a potential target to miRNA, which regulates the translation of the protein by binding to its mRNA through the 3′UTR region. Single nucleotide polymorphisms (SNPs) in this binding region could drastically affect the protein expression by affecting the number and the stability of miRNA-mRNA complexes. We found 77 miRNAs in 15 genes which were found to have altered binding efficiency because of 26 SNPs. After which, we tried to evaluate the impact of each of these SNPs on related HOX genes. Some SNPs such as SNP 15689 on the HOXB7 gene will decrease gene expression by creating or enhancing new binding sites for miRNA to mRNA, while other SNPs such as SNP 872760 on the HOXB5 gene will overexpress the gene by breaking or decreasing existing binding sites from miRNA to mRNA. Then we conducted an expression analysis to compare the mRNA expression profiles in normal and cancer tissue. Subsequently, we did an enrichment analysis followed by a network analysis to shed light on the metabolic function of the gene that could be affected by mutation and whether these mutations may affect other genes. For the first time, this study delivers information on the possible epigenetic regulation of HOX genes via the 77 miRNAs that have predicted target binding sites on HOX mRNAs, and SNPs may regulate those. Furthermore, we show that the HOX gene misregulation may influence other HOX and non-HOX genes, based on network analysis.

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Genes affected by SNPs in miRNA lead to deregulation of HOX genes that will cause cancer.

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HOX genes have role in posttranscriptional nucleic acid and protein binding.

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The mutational effect of any HOX gene affects other members of HOX genes.

Prostate cancer risk variants of the HOXB genetic locus

The G84E germline mutation of HOXB13 predisposes to prostate cancer and is clinically tested for familial cancer care. We investigated the HOXB locus to define a potentially broader contribution to prostate cancer heritability. We sought HOXB locus germline variants altering prostate cancer risk in three European-ancestry case-control study populations (combined 7812 cases and 5047 controls): the International Consortium for Prostate Cancer Genetics Study; the Nashville Familial Prostate Cancer Study; and the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Multiple rare genetic variants had concordant and strong risk effects in these study populations and exceeded genome-wide significance. Independent risk signals were best detected by sentinel variants rs559612720 within SKAP1 (OR = 8.1, P = 2E-9) and rs138213197 (G84E) within HOXB13 (OR = 5.6, P = 2E-11), separated by 567 kb. Half of carriers inherited both risk alleles, while others inherited either alone. Under mutual adjustment, the variants separately carried 3.6- and 3.1-fold risk, respectively, while joint inheritance carried 11.3-fold risk. These risks were further accentuated among men meeting criteria for hereditary prostate cancer, and further still for those with early-onset or aggressive disease. Among hereditary prostate cancer cases diagnosed under age 60 and with aggressive disease, joint inheritance carried a risk of OR = 27.7 relative to controls, P = 2E-8. The HOXB sentinel variant pair more fully captured genetic risk for prostate cancer within the study populations than either variant alone.

Identification of Germline Genetic Variants that Increase Prostate Cancer Risk and Influence Development of Aggressive Disease

Prostate cancer (PrCa) is a heterogeneous disease, which presents in individual patients across a diverse phenotypic spectrum ranging from indolent to fatal forms. No robust biomarkers are currently available to enable routine screening for PrCa or to distinguish clinically significant forms, therefore late stage identification of advanced disease and overdiagnosis plus overtreatment of insignificant disease both remain areas of concern in healthcare provision. PrCa has a substantial heritable component, and technological advances since the completion of the Human Genome Project have facilitated improved identification of inherited genetic factors influencing susceptibility to development of the disease within families and populations. These genetic markers hold promise to enable improved understanding of the biological mechanisms underpinning PrCa development, facilitate genetically informed PrCa screening programmes and guide appropriate treatment provision. However, insight remains largely lacking regarding many aspects of their manifestation; especially in relation to genes associated with aggressive phenotypes, risk factors in non-European populations and appropriate approaches to enable accurate stratification of higher and lower risk individuals. This review discusses the methodology used in the elucidation of genetic loci, genes and individual causal variants responsible for modulating PrCa susceptibility; the current state of understanding of the allelic spectrum contributing to PrCa risk; and prospective future translational applications of these discoveries in the developing eras of genomics and personalised medicine.

HOXB13 and TFF3 can contribute to the prognostic stratification of prostate adenocarcinoma

Homeobox B13 (HOXB13) and trefoil factor 3 (TFF3) are novel candidates for the classification of prostate cancer (PC) in molecular subtypes that could predict the clinical evolution of patients. The aim of our study was to analyze the possible associations between HOXB13 and TFF3 immunohistochemical (IHC) expression in sporadic prostate adenocarcinoma (PAC), the potential prognostic value in relation to the classical clinico-pathological parameters, as well as their role in defining distinct molecular subtypes of this malignancy. The study group comprised 105 patients diagnosed with PAC who underwent radical prostatectomy. IHC exam was performed using anti-HOXB13 and anti-TFF3 antibodies and a scoring system that permit the separation of the cases into two subgroups, with low and high immunoexpression, respectively. The statistical analysis evaluated the relationship between the two immunomarkers and clinico-pathological parameters. The Kaplan-Meier curves and log-rank Mantel-Cox test were used for assessing the prostate-specific antigen (PSA)-progression free survival. Four subgroups of PAC were defined based on the IHC overexpression and low immunoexpression of HOXB13 and TFF3. High HOXB13 and TFF3 immunoexpression was commonly identified in cases characterized by a Gleason score over 7, a G4 or G5 dominant pattern, a grade group of 3 or 4 and a preoperatory PSA serum level over 20 ng/mL. HOXB13 overexpression was also associated with pathological tumor-node-metastasis (pTNM) stage. The subgroup with both low HOXB13 and TFF3 immunoexpression had the highest PSA-progression free interval, whereas the subgroup with high HOXB13 immunoexpression and low TFF3 immunoexpression presented the lowest rate, but no statistically significant differences were registered. Our results sustain the role of HOXB13 and TFF3 in the stratification of PAC. Further investigations in larger cohorts are imposed to validate the clinical significance of these subgroups in the diagnostic and prognostic of PAC.

Diagnosing hereditary cancer predisposition in men with prostate cancer

PURPOSE

We describe the pathogenic variant spectrum and identify predictors of positive results among men referred for clinical genetic testing for prostate cancer.

METHODS

One thousand eight hundred twelve men with prostate cancer underwent clinical multigene panel testing between April 2012 and September 2017. Stepwise logistic regression determined the most reliable predictors of positive results among clinical variables reported on test requisition forms.

RESULTS

A yield of 9.4-12.1% was observed among men with no prior genetic testing. In this group, the positive rate of BRCA1 and BRCA2 was 4.6%; the positive rate for the mismatch repair genes was 2.8%. Increasing Gleason score (odds ratio [OR] 1.19; 95% confidence interval [CI] 0.97-1.45); personal history of breast or pancreatic cancer (OR 3.62; 95% CI 1.37-9.46); family history of breast, ovarian, or pancreatic cancer (OR 2.32 95% CI 1.48-3.65); and family history of Lynch syndrome-associated cancers (OR 1.97; 95% CI 1.23-3.15) were predictors of positive results.

CONCLUSION

These results support multigene panel testing as the primary genetic testing approach for hereditary prostate cancer and are supportive of recommendations for consideration of germline testing in men with prostate cancer. Expanding the criteria for genetic testing should be considered as many pathogenic variants are actionable for treatment of advanced prostate cancer.

The Role of BRCA Testing in Hereditary Pancreatic and Prostate Cancer Families

Beyond breast and ovarian cancers, mutations in the BRCA1 and BRCA2 genes increase risks for pancreatic and prostate cancers and contribute to the prevalence of these cancers. Mutations in a number of other genes have also been shown to increase the risk for these cancers as well. Genetic testing is playing an increasingly important role in the treatment of patients with pancreatic and prostate cancer and is now recommended for all patients with pancreatic or metastatic prostate cancer, as well as patients with high Gleason grade prostate cancer and a remarkable family history. Identification of an inherited mutation can direct evaluation of the patient for other cancer risks as well as identification and management of disease in at-risk relatives. Growing evidence suggests improved responses to PARP inhibitors and other therapies in patients with mutations in the BRCA and other DNA repair genes. Although more work must be done to clarify the prevalence and penetrance of mutations in genes other than BRCA1 and BRCA2 in patients with pancreatic and prostate cancer, in most cases, testing is now being done with a panel of multiple genes. Because of the complexities in panel testing and the increased likelihood of finding variants of uncertain significance, pre- and post-test genetic counseling are essential.

Homeobox B13 G84E Mutation and Prostate Cancer Risk

BACKGROUND

The homeobox B13 (HOXB13) G84E mutation has been recommended for use in genetic counselling for prostate cancer (PCa), but the magnitude of PCa risk conferred by this mutation is uncertain.

OBJECTIVE

To obtain precise risk estimates for mutation carriers and information on how these vary by family history and other factors.

DESIGN, SETTING, AND PARTICIPANTS

Two-fold: a systematic review and meta-analysis of published risk estimates, and a kin-cohort study comprising pedigree data on 11983 PCa patients enrolled during 1993-2014 from 189 UK hospitals and who had been genotyped for HOXB13 G84E.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Relative and absolute PCa risks. Complex segregation analysis with ascertainment adjustment to derive age-specific risks applicable to the population, and to investigate how these vary by family history and birth cohort.

RESULTS AND LIMITATIONS

A meta-analysis of case-control studies revealed significant heterogeneity between reported relative risks (RRs; range: 0.95-33.0, p<0.001) and differences by case selection (p=0.007). Based on case-control studies unselected for PCa family history, the pooled RR estimate was 3.43 (95% confidence interval [CI] 2.78-4.23). In the kin-cohort study, PCa risk for mutation carriers varied by family history (p<0.001). There was a suggestion that RRs decrease with age, but this was not significant (p=0.068). We found higher RR estimates for men from more recent birth cohorts (p=0.004): 3.09 (95% CI 2.03-4.71) for men born in 1929 or earlier and 5.96 (95% CI 4.01-8.88) for men born in 1930 or later. The absolute PCa risk by age 85 for a male HOXB13 G84E carrier varied from 60% for those with no PCa family history to 98% for those with two relatives diagnosed at young ages, compared with an average risk of 15% for noncarriers. Limitations include the reliance on self-reported cancer family history.

CONCLUSIONS

PCa risks for HOXB13 G84E mutation carriers are heterogeneous. Counselling should not be based on average risk estimates but on age-specific absolute risk estimates tailored to individual mutation carriers' family history and birth cohort.

PATIENT SUMMARY

Men who carry a hereditary mutation in the homeobox B13 (HOXB13) gene have a higher than average risk for developing prostate cancer. In our study, we examined a large number of families of men with prostate cancer recruited across UK hospitals, to assess what other factors may contribute to this risk and to assess whether we could create a precise model to help in predicting a man's prostate cancer risk. We found that the risk of developing prostate cancer in men who carry this genetic mutation is also affected by a family history of prostate cancer and their year of birth. This information can be used to assess more personalised prostate cancer risks to men who carry HOXB13 mutations and hence better counsel them on more personalised risk management options, such as tailoring prostate cancer screening frequency.

Prostate Cancer Genomics: Recent Advances and the Prevailing Underrepresentation from Racial and Ethnic Minorities

Prostate cancer (CaP) is the most commonly diagnosed non-cutaneous cancer and the second leading cause of male cancer deaths in the United States. Among African American (AA) men, CaP is the most prevalent malignancy, with disproportionately higher incidence and mortality rates. Even after discounting the influence of socioeconomic factors, the effect of molecular and genetic factors on racial disparity of CaP is evident. Earlier studies on the molecular basis for CaP disparity have focused on the influence of heritable mutations and single-nucleotide polymorphisms (SNPs). Most CaP susceptibility alleles identified based on genome-wide association studies (GWAS) were common, low-penetrance variants. Germline CaP-associated mutations that are highly penetrant, such as those found in HOXB13 and BRCA2, are usually rare. More recently, genomic studies enabled by Next-Gen Sequencing (NGS) technologies have focused on the identification of somatic mutations that contribute to CaP tumorigenesis. These studies confirmed the high prevalence of ERG gene fusions and PTEN deletions among Caucasian Americans and identified novel somatic alterations in SPOP and FOXA1 genes in early stages of CaP. Individuals with African ancestry and other minorities are often underrepresented in these large-scale genomic studies, which are performed primarily using tumors from men of European ancestry. The insufficient number of specimens from AA men and other minority populations, together with the heterogeneity in the molecular etiology of CaP across populations, challenge the generalizability of findings from these projects. Efforts to close this gap by sequencing larger numbers of tumor specimens from more diverse populations, although still at an early stage, have discovered distinct genomic alterations. These research findings can have a direct impact on the diagnosis of CaP, the stratification of patients for treatment, and can help to address the disparity in incidence and mortality of CaP. This review examines the progress of understanding in CaP genetics and genomics and highlight the need to increase the representation from minority populations.

Role of Genetic Testing for Inherited Prostate Cancer Risk: Philadelphia Prostate Cancer Consensus Conference 2017

Purpose Guidelines are limited for genetic testing for prostate cancer (PCA). The goal of this conference was to develop an expert consensus-driven working framework for comprehensive genetic evaluation of inherited PCA in the multigene testing era addressing genetic counseling, testing, and genetically informed management. Methods An expert consensus conference was convened including key stakeholders to address genetic counseling and testing, PCA screening, and management informed by evidence review. Results Consensus was strong that patients should engage in shared decision making for genetic testing. There was strong consensus to test HOXB13 for suspected hereditary PCA, BRCA1/2 for suspected hereditary breast and ovarian cancer, and DNA mismatch repair genes for suspected Lynch syndrome. There was strong consensus to factor BRCA2 mutations into PCA screening discussions. BRCA2 achieved moderate consensus for factoring into early-stage management discussion, with stronger consensus in high-risk/advanced and metastatic setting. Agreement was moderate to test all men with metastatic castration-resistant PCA, regardless of family history, with stronger agreement to test BRCA1/2 and moderate agreement to test ATM to inform prognosis and targeted therapy. Conclusion To our knowledge, this is the first comprehensive, multidisciplinary consensus statement to address a genetic evaluation framework for inherited PCA in the multigene testing era. Future research should focus on developing a working definition of familial PCA for clinical genetic testing, expanding understanding of genetic contribution to aggressive PCA, exploring clinical use of genetic testing for PCA management, genetic testing of African American males, and addressing the value framework of genetic evaluation and testing men at risk for PCA-a clinically heterogeneous disease.

Impact of the G84E variant on HOXB13 gene and protein expression in formalin-fixed, paraffin-embedded prostate tumours

The HOXB13 G84E variant is associated with risk of prostate cancer (PCa), however the role this variant plays in PCa development is unknown. This study examined 751 cases, 450 relatives and 355 controls to determine the contribution of this variant to PCa risk in Tasmania and investigated HOXB13 gene and protein expression in tumours from nine G84E heterozygote variant and 13 wild-type carriers. Quantitative PCR and immunohistochemistry showed that HOXB13 gene and protein expression did not differ between tumour samples from variant and wild-type carriers. Allele-specific transcription revealed that two of seven G84E carriers transcribed both the variant and wild-type allele, while five carriers transcribed the wild-type allele. Methylation of surrounding CpG sites was lower in the variant compared to the wild-type allele, however overall methylation across the region was very low. Notably, tumour characteristics were less aggressive in the two variant carriers that transcribed the variant allele compared to the five that did not. This study has shown that HOXB13 expression does not differ between tumour tissue of G84E variant carriers and non-carriers. Intriguingly, the G84E variant allele was rarely transcribed in carriers, suggesting that HOXB13 expression may be driven by the wild-type allele in the majority of carriers.

Oncogenic mechanisms of HOXB13 missense mutations in prostate carcinogenesis

The recurrent germline mutation HOXB13 p.(Gly84Glu) (G84E) has recently been identified as a risk factor for prostate cancer. In a recent study, we have performed full sequencing of the HOXB13 gene in 462 Portuguese prostate cancer patients with early-onset and/or familial/hereditary disease, and identified two novel missense mutations, p.(Ala128Asp) (A128D) and p.(Phe240Leu) (F240L), that were predicted to be damaging to protein function. In the present work we aimed to investigate the potential oncogenic role of these mutations, comparing to that of the recurrent G84E mutation and wild-type HOXB13. We induced site-directed mutagenesis in a HOXB13 expression vector and established in vitro cell models of prostate carcinogenesis with stable overexpression of either the wild-type or the mutated HOXB13 variants. By performing in vitro assays we observed that, while the wild-type promotes proliferation, also observed with the F240L variant along with a decrease in apoptosis, the A128D mutation decreases apoptosis and promotes anchorage independent growth. No phenotypic impact was observed for the G84E mutation in the cell line model used. Our data show that specific HOXB13 mutations are involved in the acquisition of different cancer-associated capabilities and further support an oncogenic role for HOXB13 in prostate carcinogenesis.

Association between germline homeobox B13 (HOXB13) G84E allele and prostate cancer susceptibility: a meta-analysis and trial sequential analysis

Germline HOXB13 G84E mutation (rs138213197) has been described associated with prostate cancer (PCa) susceptibility but results of different studies are inconsistent. We conducted this meta-analysis to evaluate the specific role of this mutation. Relevant available studies were identified by searching the databases Pubmed, Embase and Web of Science. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to measure the strength of the association. Subgroup analysis were performed to evaluate the specific role of rs138213197 in disease aggressiveness, diagnostic age and family history. Furthermore, trial sequential analysis (TSA) was conducted for the first time to estimate whether the evidence of the results is sufficient. Our results indicated that significant increased PCa susceptibility was associated with rs138213197 compared with non-carriers (OR = 3.38, 95% CI: 2.45-4.66). Besides, in subgroup analysis, HOXB13 G84E variant was obviously associated with early onset (OR = 2.90, 95% CI: 2.24-3.75), affected relatives (OR = 2.60, 95% CI 2.19-3.10) and highly aggressive disease (OR = 2.38, 95% CI 1.84-3.08). By TSA, the findings in the current study were based on sufficient evidence. Therefore, our results indicated that the G84E mutation in HOXB13 gene might increase susceptibility to PCa.

Germline HOXB13 p.Gly84Glu mutation and cancer susceptibility: a pooled analysis of 25 epidemiological studies with 145,257 participates

Numerous studies have investigated association between the germline HOXB13 p.Gly84Glu mutation and cancer risk. However, the results were inconsistent. Herein, we performed this meta-analysis to get a precise conclusion of the associations. A comprehensive literature search was conducted through Medline (mainly Pubmed), Embase, Cochrane Library databases. Crude odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated by STATA 12.1 software to evaluate the association of HOXB13 p.Gly84Glu mutation and cancer susceptibility. Then, 25 studies including 51,390 cases and 93,867 controls were included, and there was significant association between HOXB13 p.Gly84Glu mutation and overall cancer risk (OR = 2.872, 95% CI = 2.121-3.888, P < 0.001), particularly in prostate cancer (OR = 3.248, 95% CI = 2.313-4.560, P < 0.001), while no association was found in breast (OR = 1.424, 95% CI = 0.776-2.613, P = 0.253) and colorectal cancers (OR = 2.070, 95% CI = 0.485-8.841, P = 0.326). When we stratified analysis by ethnicity, significant association was found in Caucasians (OR = 2.673, 95%CI = 1.920-3.720, P < 0.001). Further well-designed with large samples and other various cancers should be performed to validate our results.

Familial prostate cancer

Prostate cancer is the most commonly diagnosed cancer among men in the United States as well as most Western countries. A significant proportion of men report having a positive family history of prostate cancer in a first-degree relative (father, brother, son), which is important in that family history is one of the only established risk factors for the disease and plays a role in decision-making for prostate cancer screening. Familial aggregation of prostate cancer is considered a surrogate marker of genetic susceptibility to developing the disease, but shared environment cannot be excluded as an explanation for clustering of cases among family members. Prostate cancer is both a clinically and genetically heterogeneous disease with inherited factors predicted to account for 40%-50% of cases, comprised of both rare highly to moderately penetrant gene variants, as well as common genetic variants of low penetrance. Most notably, HOXB13 and BRCA2 mutations have been consistently shown to increase prostate cancer risk, and are more commonly observed among patients diagnosed with early-onset disease. A recurrent mutation in HOXB13 has been shown to predispose to hereditary prostate cancer (HPC), and BRCA2 mutations to hereditary breast and ovarian cancer (HBOC). Genome-wide association studies (GWAS) have also identified approximately 100 loci that associate with modest (odds ratios <2.0) increases in prostate cancer risk, only some of which have been replicated in subsequent studies. Despite these efforts, genetic testing in prostate cancer lags behind other common tumors like breast and colorectal cancer. To date, National Comprehensive Cancer Network (NCCN) guidelines have highly selective criteria for BRCA1/2 testing for men with prostate cancer based on personal history and/or specific family cancer history. Tumor sequencing is also leading to the identification of germline mutations in prostate cancer patients, informing the scope of inheritance. Advances in genetic testing for inherited and familial prostate cancer (FPC) are needed to inform personalized cancer risk screening and treatment approaches.

Recurrent HOXB13 mutations in the Dutch population do not associate with increased breast cancer risk

The HOXB13 p.G84E mutation has been firmly established as a prostate cancer susceptibility allele. Although HOXB13 also plays a role in breast tumor progression, the association of HOXB13 p.G84E with breast cancer risk is less evident. Therefore, we comprehensively interrogated the entire HOXB13 coding sequence for mutations in 1,250 non-BRCA1/2 familial breast cancer cases and 800 controls. We identified two predicted deleterious missense mutations, p.G84E and p.R217C, that were recurrent among breast cancer cases and further evaluated their association with breast cancer risk in a larger study. Taken together, 4,520 familial non-BRCA1/2 breast cancer cases and 3,127 controls were genotyped including the cases and controls of the whole gene screen. The concordance rate for the genotyping assays compared with Sanger sequencing was 100%. The prostate cancer risk allele p.G84E was identified in 18 (0.56%) of 3,187 cases and 16 (0.70%) of 2,300 controls (OR = 0.81, 95% CI = 0.41–1.59, P = 0.54). Additionally, p.R217C was identified in 10 (0.31%) of 3,208 cases and 2 (0.087%) of 2,288 controls (OR = 3.57, 95% CI = 0.76–33.57, P = 0.14). These results imply that none of the recurrent HOXB13 mutations in the Dutch population are associated with breast cancer risk, although it may be worthwhile to evaluate p.R217C in a larger study.

HOXB13 overexpression is an independent predictor of early PSA recurrence in prostate cancer treated by radical prostatectomy

HOXB13 is a prostate cancer susceptibility gene which shows a cancer predisposing (G84E) mutation in 0.1–0.6% of males. We analyzed the prognostic impact of HOXB13 expression by immunohistochemistry on a tissue microarray containing more than 12,400 prostate cancers. Results were compared to tumor phenotype, biochemical recurrence, androgen receptor (AR) and prostate specific antigen (PSA) as well as molecular subtypes defined by ERG status and genomic deletions of 3p, 5q, 6q, and PTEN. HOXB13 immunostaining was detectable in 51.7% of 10,216 interpretable cancers and considered strong in 9.6%, moderate in 19.7% and weak in 22.3% of cases. HOXB13 expression was linked to advanced pT stage, high Gleason grade, positive lymph node status (p < 0.0001 each), high pre-operative PSA levels (p = 0.01), TMPRSS2:ERG fusion, PTEN deletions, AR expression, cell proliferation, reduced PSA expression and early PSA recurrence (p < 0.0001 each). The prognostic value of HOXB13 was independent from established parameters including Gleason, stage, nodal stage and PSA. Co-expression analysis identified a subset of tumors with high HOXB13 and AR but low PSA expression that had a particularly poor prognosis. HOXB13 appears to be a promising candidate for clinical routine tests either alone or in combination with other markers, including AR and PSA.

Prevalence of the HOXB13 G84E mutation in Danish men undergoing radical prostatectomy and its correlations with prostate cancer risk and aggressiveness

OBJECTIVES

To determine the prevalence of the HOXB13 G84E mutation (rs138213197) in Danish men with or without prostate cancer (PCa) and to investigate possible correlations between HOXB13 mutation status and clinicopathological characteristics associated with tumour aggressiveness.

MATERIALS AND METHODS

We conducted a case-control study including 995 men with PCa (cases) who underwent radical prostatectomy (RP) between 1997 and 2011 at the Department of Urology, Aarhus University Hospital, Denmark. As controls, we used 1622 healthy men with a normal prostate specific antigen (PSA) level.

RESULTS

The HOXB13 G84E mutation was identified in 0.49% of controls and in 2.51% of PCa cases. The mutation was associated with a 5.12-fold increased relative risk (RR) of PCa (95% confidence interval [CI] 2.26-13.38; P = 13 × 10(-6) ). Furthermore, carriers of the risk allele were significantly more likely to have a higher PSA level at diagnosis (mean PSA 19.9 vs 13.6 ng/mL; P = 0.032), a pathological Gleason score ≥7 (83.3 vs 60.9%; P = 0.032), and positive surgical margins (56.0 vs 28.5%; P = 0.006) than non-carriers. Risk allele carriers were also more likely to have aggressive disease (54.2 vs 28.6%; P = 0.011), as defined by a preoperative PSA ≥20 ng/mL, pathological Gleason score ≥ (4+3) and/or presence of regional/distant disease. At a mean follow-up of 7 months, we found no significant association between HOXB13 mutation status and biochemical recurrence in this cohort of men who underwent RP.

CONCLUSIONS

This is the first study to investigate the HOXB13 G84E mutation in Danish men. The mutation was detected in 0.49% of controls and in 2.51% of cases, and was associated with 5.12-fold increased RR of being diagnosed with PCa. In our RP cohort, HOXB13 mutation carriers were more likely to develop aggressive PCa. Further studies are needed to assess the potential of HOXB13 for future targeted screening approaches.

Identification of Two Novel HOXB13 Germline Mutations in Portuguese Prostate Cancer Patients

The HOXB13 germline variant G84E (rs138213197) was recently described in men of European descent, with the highest prevalence in Northern Europe. The G84E mutation has not been found in patients of African or Asian ancestry, which may carry other HOXB13 variants, indicating allelic heterogeneity depending on the population. In order to gain insight into the full scope of coding HOXB13 mutations in Portuguese prostate cancer patients, we decided to sequence the entire coding region of the HOXB13 gene in 462 early-onset or familial/hereditary cases. Additionally, we searched for somatic HOXB13 mutations in 178 prostate carcinomas to evaluate their prevalence in prostate carcinogenesis. Three different patients were found to carry in their germline DNA two novel missense variants, which were not identified in 132 control subjects. Both variants are predicted to be deleterious by different in silico tools. No somatic mutations were found. These findings further support the hypothesis that different rare HOXB13 mutations may be found in different ethnic groups. Detection of mutations predisposing to prostate cancer may require re-sequencing rather than genotyping, as appropriate to the population under investigation.

The HOXB13 G84E Mutation Is Associated with an Increased Risk for Prostate Cancer and Other Malignancies

BACKGROUND

A rare nonconservative substitution (G84E) in the HOXB13 gene has been shown to be associated with risk of prostate cancer. DNA samples from male patients included in the Mayo Clinic Biobank (MCB) were genotyped to determine the frequency of the G84E mutation and its association with various cancers.

METHODS

Subjects were genotyped using a custom TaqMan (Applied Biosystems) assay for G84E (rs138213197). In addition to donating a blood specimen, all MCB participants completed a baseline questionnaire to collect information on medical history and family history of cancer.

RESULTS

Forty-nine of 9,012 male patients were carriers of G84E (0.5%). Thirty-one percent (n = 2,595) of participants had been diagnosed with cancer, including 51.1% of G84E carriers compared with just 30.6% of noncarriers (P = 0.004). G84E was most frequently observed among men with prostate cancer compared with men without cancer (P < 0.0001). However, the mutation was also more commonly observed in men with bladder cancer (P = 0.06) and leukemia (P = 0.01). G84E carriers were more likely to have a positive family history of prostate cancer in a first-degree relative compared to noncarriers (36.2% vs. 16.0%, P = 0.0003).

CONCLUSIONS

Our study confirms the association between the HOXB13 G84E variant and prostate cancer and suggests a novel association between G84E and leukemia and a suggestive association with bladder cancer. Future investigation is warranted to confirm these associations in order to improve our understanding of the role of germline HOXB13 mutations in human cancer.

IMPACT

The associations between HOXB13 and prostate, leukemia, and bladder suggest that this gene is important in carcinogenesis.

Prevalence of the HOXB13 G84E germline mutation in British men and correlation with prostate cancer risk, tumour characteristics and clinical outcomes

BACKGROUND

A rare recurrent missense variant in HOXB13 (rs138213197/G84E) was recently reported to be associated with hereditary prostate cancer. Population-based studies have established that, since the frequency of this single-nucleotide polymorphism (SNP) varies between geographic regions, the associated proportion of prostate cancer (PrCa) risk contribution is also highly variable by country.

PATIENTS AND METHODS

This is the largest comprehensive case-control study assessing the prevalence of the HOXB13 G84E variant to date and is the first in the UK population. We genotyped 8652 men diagnosed with PrCa within the UK Genetic Prostate Cancer Study (UKGPCS) and 5252 healthy men from the UK ProtecT study.

RESULTS

HOXB13 G84E was identified in 0.5% of the healthy controls and 1.5% of the PrCa cases, and it was associated with a 2.93-fold increased risk of PrCa [95% confidence interval (CI) 1.94-4.59; P = 6.27 × 10(-8)]. The risk was even higher among men with family history of PrCa [odds ratio (OR) = 4.53, 95% CI 2.86-7.34; P = 3.1 × 10(-8)] and in young-onset PrCa (diagnosed up to the age of 55 years; OR = 3.11, 95% CI 1.98-5.00; P = 6.1 × 10(-7)). There was no significant association between Gleason Score, presenting prostate specific antigen, tumour-node-metastasis (TNM) stage or NCCN risk group and carrier status. HOXB13 G84E was not associated with overall or cancer-specific survival. We found that the polygenic PrCa risk score (PR score), calculated using the 71 known single-nucleotide polymorphisms (SNPs) associated with PrCa and the HOXB13 G84E variant act multiplicatively on PrCa risk. Based on the estimated prevalence and risk, this rare variant explains ∼1% of the familial risk of PrCa in the UK population.

CONCLUSIONS

The clinical importance of HOXB13 G84E in PrCa management has not been established. This variant was found to have no effect on prognostic implications but could be used for stratifying screening, by identifying men at high risk.

CLINICAL TRIALS NUMBERS

Prostate Testing for Cancer and Treatment (ProtecT): NCT02044172.

UK GENETIC PROSTATE CANCER STUDY

Epidemiology and Molecular Genetics Studies (UKGPCS): NCT01737242.

Imputation of the rare HOXB13 G84E mutation and cancer risk in a large population-based cohort

An efficient approach to characterizing the disease burden of rare genetic variants is to impute them into large well-phenotyped cohorts with existing genome-wide genotype data using large sequenced referenced panels. The success of this approach hinges on the accuracy of rare variant imputation, which remains controversial. For example, a recent study suggested that one cannot adequately impute the HOXB13 G84E mutation associated with prostate cancer risk (carrier frequency of 0.0034 in European ancestry participants in the 1000 Genomes Project). We show that by utilizing the 1000 Genomes Project data plus an enriched reference panel of mutation carriers we were able to accurately impute the G84E mutation into a large cohort of 83,285 non-Hispanic White participants from the Kaiser Permanente Research Program on Genes, Environment and Health Genetic Epidemiology Research on Adult Health and Aging cohort. Imputation authenticity was confirmed via a novel classification and regression tree method, and then empirically validated analyzing a subset of these subjects plus an additional 1,789 men from Kaiser specifically genotyped for the G84E mutation (r² = 0.57, 95% CI = 0.37−0.77). We then show the value of this approach by using the imputed data to investigate the impact of the G84E mutation on age-specific prostate cancer risk and on risk of fourteen other cancers in the cohort. The age-specific risk of prostate cancer among G84E mutation carriers was higher than among non-carriers. Risk estimates from Kaplan-Meier curves were 36.7% versus 13.6% by age 72, and 64.2% versus 24.2% by age 80, for G84E mutation carriers and non-carriers, respectively (p = 3.4×10⁻¹²). The G84E mutation was also associated with an increase in risk for the fourteen other most common cancers considered collectively (p = 5.8×10⁻⁴) and more so in cases diagnosed with multiple cancer types, both those including and not including prostate cancer, strongly suggesting pleiotropic effects.

An efficient approach to characterizing the disease burden of rare genetic variants is to impute them into existing well-phenotyped cohorts with genome-wide data by using large sequenced reference panels; however, the efficacy of this approach remains controversial. A recent study suggested that it is not possible to impute the rare HOXB13 G84E variant using neighboring SNP markers. We show that by using an enriched reference sequenced sample of 22 mutation carriers, we were able to impute this mutation into a large cohort of 83,285 non-Hispanic White individuals from the Kaiser Permanente Research Program on Genes, Environment, and Health Genetic Epidemiology Research on Adult Health and Aging (GERA) cohort. The imputation was confirmed via a novel classification and regression tree method, and then empirically validated by direct mutation genotyping of a subset of 1,673 of these individuals in addition to 1,789 other men from Kaiser. Using the same GERA cohort, we then confirmed that the G84E mutation is associated with increased risk of prostate cancer, and estimated the age-specific risk for carriers of the mutation. Finally, we obtained evidence that the mutation is associated with additional types of cancer in the GERA cohort.

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.

Prostate cancer in young men: an important clinical entity

Prostate cancer is considered a disease of older men (aged >65 years), but today over 10% of new diagnoses in the USA occur in young men aged ≤55 years. Early-onset prostate cancer, that is prostate cancer diagnosed at age ≤55 years, differs from prostate cancer diagnosed at an older age in several ways. Firstly, among men with high-grade and advanced-stage prostate cancer, those diagnosed at a young age have a higher cause-specific mortality than men diagnosed at an older age, except those over age 80 years. This finding suggests that important biological differences exist between early-onset prostate cancer and late-onset disease. Secondly, early-onset prostate cancer has a strong genetic component, which indicates that young men with prostate cancer could benefit from evaluation of genetic risk. Furthermore, although the majority of men with early-onset prostate cancer are diagnosed with low-risk disease, the extended life expectancy of these patients exposes them to long-term effects of treatment-related morbidities and to long-term risk of disease progression leading to death from prostate cancer. For these reasons, patients with early-onset prostate cancer pose unique challenges, as well as opportunities, for both research and clinical communities. Current data suggest that early-onset prostate cancer is a distinct phenotype-from both an aetiological and clinical perspective-that deserves further attention.

HOXB13 G84E-related familial prostate cancers: a clinical, histologic, and molecular survey

Recent genetic epidemiologic studies identified a germline mutation in the homeobox transcription factor, HOXB13 G84E, which is associated with markedly increased risk for prostate cancer, particularly early-onset hereditary prostate cancer. The histomorphologic and molecular features of cancers arising in such carriers have not been studied. Here, we reviewed prostatectomy specimens from 23 HOXB13 G84E mutation carriers, mapping the total cancer burden by anatomically distinct cancer focus and evaluating morphologic features. We also assessed basic molecular subtypes for all cancer foci (ERG/SPINK1 status) by dual immunohistochemistry staining on full sections. The cohort showed a median age of 58 years, a median serum PSA level of 5.7 ng/mL, and a median of 6 cancer foci (range, 1 to 14) per case. Of evaluable cases, dominant foci were Gleason score 6 in 23%, 3+4=7 in 41%, 4+3=7 in 23%, and ≥8 in 14%; biochemical recurrence was observed in 1 case over a median of 36 months follow-up. Histologic review found a high prevalence of cases showing cancers with a spectrum of features previously described with pseudohyperplastic carcinomas, with 45% of cases showing a dominant focus with such features. Molecular subtyping revealed a strikingly low prevalence of ERG cancer with increased prevalence of SPINK1 cancer (dominant focus ERG 17%, SPINK1 26%, ERG/SPINK1 52%, single ERG/SPINK1 focus 4%). One ERG/SPINK1 dominant focus showed aberrant p63 immunophenotype. In summary, HOXB13 G84E variant-related prostate cancers show frequent pseudohyperplastic-type features and markedly low prevalence of ERG cancers relative to unselected cases and, especially, to early-onset cohorts. These findings suggest that novel molecular pathways may drive disease in HOXB13 G84E carriers.

Prevalence of the HOXB13 G84E prostate cancer risk allele in men treated with radical prostatectomy

OBJECTIVE

To determine the prevalence and clinical correlates of the G84E mutation in the homeobox transcription factor, or HOXB13, gene using DNA samples from 9559 men with prostate cancer undergoing radical prostatectomy.

PATIENTS AND METHODS

DNA samples from men treated with radical prostatectomy at the University of Michigan and John Hopkins University were genotyped for G84E and this was confirmed by Sanger sequencing. The frequency and distribution of this allele was determined according to specific patient characteristics (family history, age at diagnosis, pathological Gleason grade and stage).

RESULTS

Of 9559 patients, 128 (1.3%) were heterozygous carriers of G84E. Patients who possessed the variant were more likely to have a family history of prostate cancer than those who did not (46.0 vs 35.4%; P = 0.006). G84E carriers were also more likely to be diagnosed at a younger age than non-carriers (55.2 years vs 58.1 years; P < 0.001). No difference in the proportion of patients diagnosed with high grade or advanced stage tumours according to carrier status was observed.

CONCLUSIONS

In the present study, carriers of the rare G84E variant in HOXB13 were both younger at the time of diagnosis and more likely to have a family history of prostate cancer compared with homozygotes for the wild-type allele. No significant differences in allele frequency were detected according to selected clinical characteristics of prostate cancer. Further investigation is required to evaluate the role of HOXB13 in prostate carcinogenesis.

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

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

Prevalence of the HOXB13 G84E mutation among unaffected men with a family history of prostate cancer

HOXB13 (G84E) was reported to significantly increase risk for prostate cancer. The goal of the current analysis was to assess the prevalence of G84E in ethnically-diverse high-risk men undergoing prostate cancer screening and place the carrier frequency within the context of prevalence estimates from reported studies to gain insight into the future role of this mutation in genetic counseling. PRAP is a prostate cancer screening program for unaffected men ages 35-69 with a family history of prostate cancer or African descent. HOXB13 G84E was genotyped by pyrosequencing in 649 PRAP participants with available DNA. Prevalence of the mutation was calculated for PRAP and for reported studies and exact binomial confidence intervals were generated. Prevalence of the G84E mutation in non-African PRAP men was 0.73 %. When placed in context of the literature, this was higher than reported controls. One G84E mutation carrier was notably of Hispanic background. While the HOXB13 G84E mutation may be rare, there may be a future role in genetic testing for this mutation after further studies of clinical utility in assessing prostate cancer risk.

G84E mutation in HOXB13 is firmly associated with prostate cancer risk: a meta-analysis

The rare but recurrent germline G84E mutation in HOXB13 was recently found to be associated with a significantly increased risk of familial prostate cancer (PCa). However, epidemiologic findings have been inconsistent. In an attempt to confirm and expand the findings that the PCa risk increased in men carrying G84E, we therefore performed a meta-analysis to clarify the association between the germline G84E mutation and PCa risk. We also aim to verify the increased PCa risk with respect to diagnostic age, family history, and disease aggressiveness. Comprehensive search of databases was carried out, and other relevant articles were also identified. Then, the meta-analyses were conducted according to the standard guidelines. A total of 11 studies with 120,167 participants were included on the basis of inclusion criteria. The G84E allele carrier frequencies ranged from 0.1 to 4.9 % in the patients with PCa, as compared with 0 to 1.4 % in control subjects. Men with the HOXB13 G84E variant had a 4.51-fold higher relative risk of PCa compared with non-carriers (95 % CI 3.28-6.20). The much higher risks were observed in individuals with early onset (odds ratio (OR) = 9.73, 95 % confidence interval (CI) 6.57-14.39), more than two affected relatives (OR = 7.27, 95 % CI 4.02-13.15), and highly aggressive disease (OR = 5.81, 95 % CI 3.72-9.08). Our findings provide further evidences that the rare mutation in HOXB13 contributes to both hereditary and sporadic PCa risk. Despite the low G84E carrier rate, biological and clinical implications of the mutation in subjects with early onset, more than two affected relatives, and highly aggressive disease remain important in continued investigation.