Genetic counseling for prostate cancer risk

CanRisk-Prostate: A Comprehensive, Externally Validated Risk Model for the Prediction of Future Prostate Cancer

PURPOSE

Prostate cancer (PCa) is highly heritable. No validated PCa risk model currently exists. We therefore sought to develop a genetic risk model that can provide personalized predicted PCa risks on the basis of known moderate- to high-risk pathogenic variants, low-risk common genetic variants, and explicit cancer family history, and to externally validate the model in an independent prospective cohort.

MATERIALS AND METHODS

We developed a risk model using a kin-cohort comprising individuals from 16,633 PCa families ascertained in the United Kingdom from 1993 to 2017 from the UK Genetic Prostate Cancer Study, and complex segregation analysis adjusting for ascertainment. The model was externally validated in 170,850 unaffected men (7,624 incident PCas) recruited from 2006 to 2010 to the independent UK Biobank prospective cohort study.

RESULTS

The most parsimonious model included the effects of pathogenic variants in BRCA2, HOXB13, and BRCA1, and a polygenic score on the basis of 268 common low-risk variants. Residual familial risk was modeled by a hypothetical recessively inherited variant and a polygenic component whose standard deviation decreased log-linearly with age. The model predicted familial risks that were consistent with those reported in previous observational studies. In the validation cohort, the model discriminated well between unaffected men and men with incident PCas within 5 years (C-index, 0.790; 95% CI, 0.783 to 0.797) and 10 years (C-index, 0.772; 95% CI, 0.768 to 0.777). The 50% of men with highest predicted risks captured 86.3% of PCa cases within 10 years.

CONCLUSION

To our knowledge, this is the first validated risk model offering personalized PCa risks. The model will assist in counseling men concerned about their risk and can facilitate future risk-stratified population screening approaches.

Engaging Men With BRCA-Related Cancer Risks: Practical Advice for BRCA Risk Management From Male Stakeholders

Men are at risk for developing hereditary cancers such as breast, prostate, pancreatic, and melanoma due to a pathogenic germline variant in either the BRCA1 or BRCA2 gene. The purpose of this study was to identify and provide practical advice for men managing their BRCA-related cancer risks based on men's real-life experiences. Semistructured interviews were conducted with 25 men who either tested positive for a pathogenic variant in BRCA1/2 gene or who had an immediate family member who had tested positive for a pathogenic variant in BRCA1/2. A thematic analysis of the interview transcripts was completed utilizing the constant comparison method. Qualitative analysis produced three categories of participant advice for men who recently learned of their hereditary cancer risk. Specifically, participants advised the following: (a) know the basics, (b) engage in the family narrative, and (c) advocate for yourself. Results showed the need for men to know and understand their BRCA cancer risks and communicate that genetic risk information to their family members and practitioners. In particular, the findings stress the importance of addressing men's risks and medical management from a family-focused approach. Overall, because men are historically undereducated about their BRCA-related cancer risks, this practical advice serves as a first step for men managing BRCA-related cancer risks and may ultimately assist them in making preventive and screening health behaviors.

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.

The genetic epidemiology of prostate cancer and its clinical implications

Worldwide, familial and epidemiological studies have generated considerable evidence of an inherited component to prostate cancer. Indeed, rare highly penetrant genetic mutations have been implicated. Genome-wide association studies (GWAS) have also identified 76 susceptibility loci associated with prostate cancer risk, which occur commonly but are of low penetrance. However, these mutations interact multiplicatively, which can result in substantially increased risk. Currently, approximately 30% of the familial risk is due to such variants. Evaluating the functional aspects of these variants would contribute to our understanding of prostate cancer aetiology and would enable population risk stratification for screening. Furthermore, understanding the genetic risks of prostate cancer might inform predictions of treatment responses and toxicities, with the goal of personalized therapy. However, risk modelling and clinical translational research are needed before we can translate risk profiles generated from these variants into use in the clinical setting for targeted screening and treatment.

Association between single nucleotide polymorphisms on chromosome 17q and the risk of prostate cancer in a Chinese population

In European populations, 7 single nucleotide polymorphisms (SNPs) on chromosome 17q, 3 SNPs on 17q12, and 4 SNPs on 17q24.3 were recently identified to be closely related to the risk of prostate cancer by a genome-wide association study. In Japanese populations, the correlation between 2 SNPs on 17q and the risk of prostate cancer and tumor aggressiveness was also confirmed by a large-scale experiment. However, whether 17q is associated with prostate cancer and its clinical manifestations in Chinese populations is still unknown. Therefore, we conducted a case-control study in a northern Chinese population and tested 2 SNPs, rs4430796 and rs1859962, on 17q in 124 prostate cancer patients and 111 controls using polymerase chain reaction-high resolution melting curve (PCR-HRM) combined with sequencing. We analyzed the association of the 2 SNPs with the risk of prostate cancer as well as patients' lifestyles, onset ages, Gleason scores, PSA levels, and pathologic stages. We found a significant difference in the G allele of SNP rs1859962 (P = 0.035, OR = 1.51, 95% CI = 1.03-2.21) but not in the rs4430796 genotype frequency or allele frequency distribution between prostate cancer patients and the controls (P > 0.05). Neither of the SNPs was significantly associated with the onset age, Gleason score, PSA level, pathologic stage, or other clinical indicators of patients with prostate cancer (P > 0.05). Our results show that polymorphism of the G allele of SNP rs1859962 is associated with the risk of prostate cancer in a Chinese population.

A systematic review of replication studies of prostate cancer susceptibility genetic variants in high-risk men originally identified from genome-wide association studies

BACKGROUND

Several prostate cancer genome-wide association studies (GWAS) have identified risk-associated genetic variants primarily in populations of European descent. Less is known about the association of these variants in high-risk populations, including men of African descent and men with a family history of prostate cancer. This article provides a detailed review of published studies of prostate cancer-associated genetic variants originally identified in GWAS and replicated in high-risk populations.

METHODS

Articles replicating GWAS findings (National Human Genome Research Institute GWAS database) were identified by searching PubMed and relevant data were extracted.

RESULTS

Eleven replication studies were eligible for inclusion in this review. Of more than 30 single-nucleotide polymorphisms (SNP) identified in prostate cancer GWAS, 19 SNPs (63%) were replicated in men of African descent and 10 SNPs (33%) were replicated in men with familial and/or hereditary prostate cancer (FPC/HPC). The majority of SNPs were located at the 8q24 region with modest effect sizes (OR 1.11-2.63 in African American men and OR 1.3-2.51 in men with FPC). All replicated SNPs at 8q24 among men of African descent were within or near regions 2 and 3.

CONCLUSIONS

This systematic review revealed several GWAS markers with replicated associations with prostate cancer in men of African descent and men with FPC/HPC. The 8q24 region continues to be the most implicated in prostate cancer risk. These replication data support ongoing study of clinical utility and potential function of these prostate cancer-associated variants in high-risk men.

IMPACT

The replicated SNPs presented in this review hold promise for personalizing risk assessment for prostate cancer for high-risk men upon further study.

Reducing prostate cancer morbidity and mortality in African American men: issues and challenges

Prostate cancer is the most commonly diagnosed cancer in men in the United States. It disproportionately affects African American men when compared to other ethnic groups. African American men are two to three times more likely to die of prostate cancer than white men. The reasons for the disparity remain unclear, but several factors may be involved, such as age, race, nationality, nutrition, exercise, and family history of cancer. Detection of prostate cancer in high-risk African Americans is important but continues to be controversial. This article reviews the current issues and challenges regarding prostate cancer in African American men. Nurses play a vital role in the health care and education of patients; therefore, they must be aware of the issues.

Physical Activity and the Risk of Prostate Cancer in The Netherlands Cohort Study, Results after 9.3 Years of Follow-up

BACKGROUND

The aim of the current study was to evaluate the relation between physical activity and prostate cancer risk with specific emphasis on interaction with body mass index (BMI) and baseline energy intake.

METHODS

The association between prostate cancer and physical activity was evaluated in the Netherlands Cohort Study, conducted among 58,279 men ages 55 to 69 years at entry. Information regarding baseline nonoccupational physical activity, history of sports participation, and occupational physical activity was collected with a questionnaire in 1986. After 9.3 years, 1,386 incident prostate cancer cases were available for case-cohort analyses. Multivariate incidence rate ratios (RR) and corresponding 95% confidence intervals (95% CI) were calculated using Cox regression analyses.

RESULTS

Neither baseline nonoccupational physical activity (RR, 1.01; 95% CI, 0.81-1.25 for >90 versus <30 minutes per day), history of sports participation (RR, 1.04; 95% CI, 0.90-1.22 for ever versus never participated), nor occupational physical activity (RR, 0.91; 95% CI, 0.70-1.18 for >12 versus <8 KJ/min energy expenditure in the longest held job) showed an inverse relation with prostate cancer risk. We found an increased risk of prostate cancer for men who were physically active for >1 hour per day in obese men (BMI > 30) and men with a high baseline energy intake.

DISCUSSION

The results of this current study do not support the hypothesis that physical activity protects against prostate cancer in men.