BRCA population screening for predicting breast cancer: for or against?

BRCA1/2 testing for genetic susceptibility to cancer after 25 years: A scoping review and a primer on ethical implications

BACKGROUND

Mutations in the genes called BRCA1 and BRCA2 are associated with significantly elevated lifetime risk of developing breast and ovarian cancer. This year marks 25 years since genetic tests for BRCA1/2 mutations became available to the public. Currently, comprehensive guidelines exist regarding BRCA1/2 testing and preventive measures in mutation carriers. As such, BRCA1/2 testing represents a precedent not only in genetic testing and management of genetic cancer risk, but also in bioethics. The goal of the current research was to offer a review and an ethical primer of the main ethical challenges related to BRCA testing.

METHOD

A systematic scoping review was undertaken following the PRISMA Extension for Scoping Reviews (PRISMA-ScR). Four databases were searched and 18 articles that met the inclusion criteria were synthetized narratively into a conceptual map.

RESULTS

Ethical discussions revolved around the BRCA1/2 gene discovery, how tests are distributed for clinical use, the choice to undergo testing, unresolved issues in receiving and disclosing test results, reproductive decision-making, and culture-specific ethics. Several unique properties of the latest developments in testing circumstances (e.g., incorporation of BRCA1/2 testing in multi-gene or whole genome sequence panels and tests sold directly to consumers) significantly raised the complexity of ethical debates.

CONCLUSIONS

Multidisciplinary ethical discussion is necessary to guide not only individual decision making but also societal practices and medical guidelines in light of the new technologies available and the latest results regarding psychological, social, and health outcomes in cancer previvors and survivors affected by BRCA mutations.

A review of the endocrine resistance in hormone-positive breast cancer

Hormone-positive breast cancer (BC) is a unique heterogeneous disease with a favorable prognosis compared to other types of breast cancer. As tumor biology influences the prognosis and clinical treatment, a deep understanding of how the molecular mechanisms regulate hormone sensitivity or resistance is critical in improving the efficacy and overcoming the endocrine resistance. This article comprehensively reviews the endocrine resistance in hormone-positive BC from a molecular and genetic perspective, encompassing the updated treatment and developing direction. This review includes the mechanisms of hormone resistance, which vary from epigenetic changes, crosstalk between signaling networks, cell cycle aberrance, and even change in the tumor microenvironment (TME) or stem cell. These mechanisms may contribute to treatment resistance. Current targeted therapy for hormone-resistant tumors includes PI3K/AKT/mTOR and cdk4/6 inhibitors. Several relevant pathways, biomarkers, and predictor genes have also been identified. Immunotherapy so far has a relatively less crucial role in hormone-positive than in triple-negative BC. Furthermore, the methodology to identify the PDL1 is not standardized. In a molecule and gene study, next-generation sequencing with circulating tumor DNA (ctDNA) has recently appeared as a sensitive and minimally invasive tool worth investigating.

The Fanconi anemia pathway and Breast Cancer: A comprehensive review of clinical data

The development of breast cancer depends on several risk factors, including environmental, lifestyle and genetic factors. Despite the evolution of DNA sequencing techniques and biomarker detection, the epidemiology and mechanisms of various breast cancer susceptibility genes have not been elucidated yet. Dysregulation of the DNA damage response causes genomic instability and increases the rate of mutagenesis and the risk of carcinogenesis. The Fanconi Anemia (FA) pathway is an important component of the DNA damage response and plays a critical role in the repair of DNA interstrand crosslinks and genomic stability. The FA pathway involves 22 recognized genes and specific mutations have been identified as the underlying defect in the majority of FA patients. A thorough understanding of the function and epidemiology of these genes in breast cancer is critical for the development and implementation of individualized therapies that target unique tumor profiles. Targeted therapies (PARP inhibitors) exploiting the FA pathway gene defects have been developed and have shown promising results. This narrative review summarizes the current literature on the involvement of FA genes in sporadic and familial breast cancer with a focus on clinical data derived from large cohorts.

Penetrance of Breast Cancer Susceptibility Genes From the eMERGE III Network

Background

Unbiased estimates of penetrance are challenging but critically important to make informed choices about strategies for risk management through increased surveillance and risk-reducing interventions.

Methods

We studied the penetrance and clinical outcomes of 7 breast cancer susceptibility genes (BRCA1, BRCA2, TP53, CHEK2, ATM, PALB2, and PTEN) in almost 13 458 participants unselected for personal or family history of breast cancer. We identified 242 female participants with pathogenic or likely pathogenic variants in 1 of the 7 genes for penetrance analyses, and 147 women did not previously know their genetic results.

Results

Out of the 147 women, 32 women were diagnosed with breast cancer at an average age of 52.8 years. Estimated penetrance by age 60 years ranged from 17.8% to 43.8%, depending on the gene. In clinical-impact analysis, 42.3% (95% confidence interval = 31.3% to 53.3%) of women had taken actions related to their genetic results, and 2 new breast cancer cases were identified within the first 12 months after genetic results disclosure.

Conclusions

Our study provides population-based penetrance estimates for the understudied genes CHEK2, ATM, and PALB2 and highlights the importance of using unselected populations for penetrance studies. It also demonstrates the potential clinical impact of genetic testing to improve health care through early diagnosis and preventative screening.

Of Screening, Stratification, and Scores

Technological innovations including risk-stratification algorithms and large databases of longitudinal population health data and genetic data are allowing us to develop a deeper understanding how individual behaviors, characteristics, and genetics are related to health risk. The clinical implementation of risk-stratified screening programmes that utilise risk scores to allocate patients into tiers of health risk is foreseeable in the future. Legal and ethical challenges associated with risk-stratified cancer care must, however, be addressed. Obtaining access to the rich health data that are required to perform risk-stratification, ensuring equitable access to risk-stratified care, ensuring that algorithms that perform risk-scoring are representative of human genetic diversity, and determining the appropriate follow-up to be provided to stratification participants to alert them to changes in their risk score are among the principal ethical and legal challenges. Accounting for the great burden that regulatory requirements could impose on access to risk-scoring technologies is another critical consideration.

The Relationship of Mutation Carriage of BRCA1/2 and Family History in Triple-Negative Breast Cancer: Experience from a Diagnostic Center in Turkey

Objective

BRCA1/2 genes play a role in the etiopathogenesis of 10%-30% of triple-negative breast cancer (TNBC). This study aims to investigate the BRCA1/2 genes and the demographic and clinicopathological features in patients with TNBC. The study also examined the impact of cancer history of TNBC individuals' relatives on the risk of BRCA1/2 mutation carriership rate.

Materials and Methods

The BRCA1/2 genes of 65 women diagnosed with TNBC between 2011 and 2017 were investigated using next-generation sequencing. We analyzed the correlations of patients' demographic and clinicopathologic parameters and family history with BRCA1/2 mutation status. We used the χ²-test, t-test, Mann-Whitney U test, and logistic regression statistical methods.

Results

The BRCA1/2 mutation carrier rate was 16.9%. Patients who had BRCA1/2 mutations were compared with those who did not in terms of demographic and clinicopathological parameters. In the BRCA1/2 mutation carrier group, the Ki-67 index and the number of relatives with cancer were higher than the BRCA1/2 non-carrier group. Logistic regression analysis revealed that when the number of relatives with breast or ovarian cancer was ≥2, the risk of carrying the BRCA1/2 mutation increased by 15-fold. Regardless of the type of cancer (including cancers in other organs besides breast or ovary), the risk of carrying the BRCA1/2 mutation increased 1.3 times with each increase in the number of relatives with cancer for the patient with TNBC.

Conclusion

In cases with a diagnosis of TNBC, a significant relationship exists between the number of relatives with cancer in the family history and the risk of carrying mutations in the BRCA1/2 genes. This relationship can be confirmed further by large-scale studies with more cases.

Current practices on genetic testing in ovarian cancer

Epithelial ovarian cancer (EOC) is probably the tumor type with the highest percentage of hereditary cases observed, irrespectively of selection criteria. A fourth to a fifth of unselected epithelial EOC patients carry pathogenic variants (PVs) in a number of genes, the majority of which encode for proteins involved in DNA repair pathways. BRCA1 and BRCA2 predisposing PVs were the first to be associated to ovarian cancer, with the advent in DNA sequencing technologies leading to the discovery and association of additional genes which compromise the homologous recombination (HR) pathway. In addition, PVs genes involved in mismatch repair (MMR) pathway, account for 10–15% of hereditary EOC. The identification of women with HR deficient ovarian cancers has significant clinical implications concerning chemotherapy regimen planning and development and use of targeted therapies as well. More specifically, in patients with BRCA1/2 PVs or HR deficiency maintenance treatment with poly(ADP-ribose) polymerase (PARP) inhibitors, either in the first line setting or in recurrent disease, improves the progression-free survival. But also patients with HR proficient tumors show a benefit. Therefore, genetic testing in ovarian cancer has a prognostic and predictive value. In this review, we discuss which ovarian cancer patients should be referred for genetic counseling and how to perform genetic testing. We also discuss the timing of genetic testing and its clinical relevance to BRCA status.

Association between MIR499A rs3746444 polymorphism and breast cancer susceptibility: a meta-analysis

Numerous studies have investigated the association of MIR499A rs3746444 polymorphism with breast cancer susceptibility, but the results have been inconsistent. In this work, we performed a meta-analysis to obtain a more reliable estimate of the association between the polymorphism and susceptibility to breast cancer. A comprehensive literature search was conducted on PubMed, Scopus, Web of Science (WoS), China National Knowledge Infrastructure (CNKI), VIP and Wanfang databases up to January 2020. A total of 14 studies involving 6,797 cases and 8,534 controls were included for analysis under five genetic models: homozygous (GG vs. AA), heterozygous (AG vs. AA), dominant (AG + GG vs. AA), recessive (GG vs. AA + AG) and allele (G vs. A). A statistically significant association was observed between the polymorphism and an increased breast cancer susceptibility under all genetic models (homozygous, OR = 1.33, 95% CI = 1.03-1.71, P = 0.03; heterozygous, OR = 1.08, 95% CI = 1.00-1.16, P = 0.04; dominant, OR = 1.15, 95% CI = 1.02-1.30; P = 0.03; recessive, OR = 1.35, 95% CI = 1.06-1.72, P = 0.01; allele, OR = 1.12, 95% CI = 1.00-1.26, P = 0.04). Subgroup analysis based on ethnicity suggested that significant association was present only among Asians, but not Caucasians. In conclusion, MIR499A rs3746444 polymorphism was significantly associated with breast cancer susceptibility among Asians, suggesting its potential use as a genetic risk marker in this population.

Lessons Learned from Direct-to-Consumer Genetic Testing

The number of companies offering direct-to-consumer genetic tests is increasing. There is growing concern over whether direct-to-consumer genetic companies should be allowed to offer clinically relevant testing that has only been possible under medical care. Direct-to-consumer genetic testing can be incomplete, inaccurate, and inappropriate. The usefulness of such testing is extremely limited and it is unclear how well customers understand reported results. Research on the long-term impact of direct-to-consumer genetic testing is necessary to determine if stricter regulations regarding the performance of direct-to-consumer genetic testing are necessary.

Epithelial ovarian cancer risk: A review of the current genetic landscape

Ovarian cancer is the fourth most common cause of cancer-related death in women in the developed world, and one of the most heritable cancers. One of the most significant risk factors for epithelial ovarian cancer (EOC) is a family history of breast and/or ovarian cancer. Combined risk factors can be used in models to stratify risk of EOC, and aid in decisions regarding risk-reduction strategies. Germline pathogenic variants in EOC susceptibility genes including those involved in homologous recombination and mismatch repair pathways are present in approximately 22% to 25% of EOC. These genes are associated with an estimated lifetime risk of EOC of 13% to 60% for BRCA1 variants and 10% to 25% for BRCA2 variants, with lower risks associated with remaining genes. Genome-wide association studies have identified single nucleotide polymorphisms (SNPs) thought to explain an additional 6.4% of the familial risk of ovarian cancer, with 34 susceptibility loci identified to date. However, an unknown proportion of the genetic component of EOC risk remains unexplained. This review comprises an overview of individual genes and SNPs suspected to contribute to risk of EOC, and discusses use of a polygenic risk score to predict individual cancer risk more accurately.

Inequities in genetic testing for hereditary breast cancer: implications for public health practice

The Ontario Breast Screening Program for women with a genetic predisposition to breast cancer is one of the first international models of a government-funded public health service that offers systematic genetic screening to women at a high risk of breast cancer. However, since the implementation of the program in 2011, enrolment rates have been lower than anticipated. Whilst there may be several reasons for this to happen, it does call into consideration the 'inverse equity law', whereby the more advantaged in society are the first to participate and benefit from universal health services. An outcome of this phenomenon is an increase in the health divide between those that are at a social advantage versus those that are not. Using an intersectionality lens, this paper explores the role of the social determinants of health and social identity in creating possible barriers in the access to genetic screening for hereditary breast cancer, and the implications for public health practice in recognising and ameliorating these differences.