Risks of breast or ovarian cancer in BRCA1 or BRCA2 predictive test negatives: findings from the EMBRACE study

Refinement of the assignment to the ACMG/AMP BS3 and PS3 criteria of eight BRCA1 variants of uncertain significance by integrating available functional data with protein interaction assays

The clinical screening of cancer predisposition genes has led to the identification of a large number of variants of uncertain significance (VUS). Multifactorial likelihood models that predict the odds ratio for VUS in favor or against cancer causality, have been developed, but their use is limited by the amount of necessary data, which are difficult to obtain for rare variants. The guidelines for variant interpretation of the American College of Medical Genetics and Genomics along with the Association for Molecular Pathology (ACMG/AMP) state that "well-established" functional studies provide strong support of a pathogenic or benign impact (criteria PS3 and BS3, respectively) and can be used as evidence type to reach a final classification. Moreover, the Clinical Genome Resource Sequence Variant Interpretation Working Group developed rule specifications to refine the PS3/BS3 criteria. Recently, Lira PC et al. developed the "Hi Set" approach that generated PS3/BS3 codes for over two-thousands BRCA1 VUS. While highly successful, this approach did not discriminate a group of variants with conflicting evidences. Here, we aimed to implement the outcomes of the "Hi-set" approach applying Green Fluorescent Protein (GFP)-reassembly assays, assessing the effect of variants in the RING and BRCT domains of BRCA1 on the binding of these domains with the UbcH5a or ABRAXAS proteins, respectively. The analyses of 26 clinically classified variants, including 13 tested in our previous study, showed 100% sensitivity and specificity in identifying pathogenic and benign variants for both the RING/UbcH5a and the BRCTs/ABRAXAS interactions. We derived the strength of evidences generated by the GFP-reassembly assays corresponding to moderate for both PS3 and BS3 criteria assessment. The GFP-reassembly assays were applied to the functional characterization of 8 discordant variants from the study by Lyra et al. The outcomes of these analyses, combined with those reported in the "Hi Set" study, allowed the assignment of ACMG/AMP criteria in favor or against pathogenicity for all 8 examined variants. The above findings were validated with a semi-quantitative Mammalian Two-Hybrid approach, and totally concordant results were observed. Our data contributes in shedding light on the functional significance of BRCA1 VUS and on their clinical interpretation within the ACMG/AMP framework.

Cost-Effectiveness of BRCA 1/2 Genetic Test and Preventive Strategies: Using Real-World Data From an Upper-Middle Income Country

Although BRCA1/2 genetic testing in developed countries is part of the reality for high-risk patients for hereditary breast and ovarian cancer (HBOC), the same is not true for upper-middle-income countries. For that reason, this study aimed to evaluate whether the BRCA1/2 genetic test and preventive strategies for women at high risk for HBOC are cost-effective compared to not performing these strategies in an upper-middle-income country. Adopting a payer perspective, a Markov model with a time horizon of 70 years was built to delineate the health states for a cohort of healthy women aged 30 years that fulfilled the BRCA1/2 testing criteria according to the guidelines. Transition probabilities were calculated based on real-world data of women tested for BRCA1/2 germline mutations in a cancer reference hospital from 2011 to 2020. We analyzed 275 BRCA mutated index cases and 356 BRCA mutation carriers that were first- or second-degree relatives of the patients. Costs were based on the Brazilian public health system reimbursement values. Health state utilities were retrieved from literature. The BRCA1/2 genetic test and preventive strategies result in more quality-adjusted life years (QALYs) and costs with an incremental cost-effectiveness ratio of R$ 11,900.31 (U$ 5,504.31)/QALY. This result can represent a strong argument in favor of implementing genetic testing strategies for high-risk women even in countries with upper-middle income, considering not only the cancer prevention possibilities associated with the genetic testing but also its cost-effectiveness to the health system. These strategies are cost-effective, considering a willingness-to-pay threshold of R$ 25,000 (U$ 11,563.37)/QALY, indicating that the government should consider offering them for women at high risk for HBOC. The results were robust in deterministic and probabilistic sensitivity analyses.

Comprehensive Study of Germline Mutations and Double-Hit Events in Esophageal Squamous Cell Cancer

Esophageal squamous cell cancer (ESCC) is the eighth most common cancer around the world. Several reports have focused on somatic mutations and common germline mutations in ESCC. However, the contributions of pathogenic germline alterations in cancer susceptibility genes (CSGs), highly frequently mutated CSGs, and pathogenically mutated CSG-related pathways in ESCC remain unclear. We obtained data on 571 ESCC cases from public databases and East Asian from the 1000 Genomes Project database and the China Metabolic Analytics Project database to characterize pathogenic mutations. We detected 157 mutations in 75 CSGs, accounting for 25.0% (143/571) of ESCC cases. Six genes had more than five mutations: TP53 (n = 15 mutations), GJB2 (n = 8), BRCA2 (n = 6), RECQL4 (n = 6), MUTYH (n = 6), and PMS2 (n = 5). Our results identified significant differences in pathogenic germline mutations of TP53, BRCA2, and RECQL4 between the ESCC and control cohorts. Moreover, we identified 84 double-hit events (16 germline/somatic double-hit events and 68 somatic/somatic double-hit events) occurring in 18 tumor suppressor genes from 83 patients. Patients who had ESCC with germline/somatic double-hit events were diagnosed at younger ages than patients with the somatic/somatic double-hit events, though the correlation was not significant. Fanconi anemia was the most enriched pathway of pathogenically mutated CSGs, and it appeared to be a primary pathway for ESCC predisposition. The results of this study identified the underlying roles that pathogenic germline mutations in CSGs play in ESCC pathogenesis, increased our awareness about the genetic basis of ESCC, and provided suggestions for using highly mutated CSGs and double-hit features in the early discovery, prevention, and genetic counseling of ESCC.

Economic Modelling of Screen-and-Treat Strategies for Brazilian Women at Risk of Hereditary Breast and Ovarian Cancer

BACKGROUND

Clinical evidence supports the use of genetic counselling and BRCA1/2 testing for women at risk for hereditary breast and ovarian cancer. Currently, screen-and-treat strategies are not reimbursed in the Brazilian Unified Healthcare System (SUS). The aim of this modelling study was to evaluate the cost effectiveness of a gene-based screen-and-treat strategy for BRCA1/2 in women with a high familial risk followed by preventive interventions compared with no screening.

METHODS

Adopting the SUS perspective, a Markov model with a lifelong time horizon was developed for a cohort of healthy women aged 30 years that fulfilled the criteria for BRCA1/2 testing according to the National Comprehensive Cancer Network (NCCN) guideline. For women who tested positive, preventive options included intensified surveillance, risk-reducing bilateral mastectomy and bilateral salpingo-oophorectomy. The Markov model comprised the health states 'well', 'breast cancer', 'death' and two post-cancer states. Outcomes were the incremental costs per quality-adjusted life-year (QALY) and the incremental costs per life-year gained (LYG). Data were mainly obtained by a literature review. Deterministic and probabilistic sensitivity analyses were performed to assess the robustness of the results.

RESULTS

In the base case, the screen-and-treat strategy resulted in additional costs of 3515 Brazilian reais (R$) (US$1698) and a gain of 0.145 QALYs, compared with no screening. The incremental cost-effectiveness ratio (ICER) was R$24,263 (US$21,724) per QALY and R$27,258 (US$24,405) per LYG. Applying deterministic sensitivity analyses, the ICER was most sensitive to the probability of a positive test result and the discount rate. In the probabilistic sensitivity analysis, a willingness to pay of R$25,000 per QALY gained for the screen-and-treat strategy resulted in a probability of cost effectiveness of 80%.

CONCLUSION

Although there is no rigorous cost-effectiveness threshold in Brazil, the result of this cost-effectiveness analysis may support the inclusion of BRCA1/2 testing for women at high-risk of cancer in the SUS. The ICER calculated for the provision of genetic testing for BRCA1/2 approximates the cost-effectiveness threshold proposed by the World Health Organization (WHO) for low- and middle-income countries.

Ras-Mediated Activation of NF-κB and DNA Damage Response in Carcinogenesis

Cancer is a multi-step process during which cells acquire mutations that eventually lead to uncontrolled cell growth and division and evasion of programmed cell death. The oncogenes such as Ras and c-Myc may be responsible in all three major stages of cancer i.e., early, intermediate, and late. The NF-κB has been shown to control the expression of genes linked with tumor pathways such as chronic inflammation, tumor cell survival, anti-apoptosis, proliferation, invasion, and angiogenesis. In the last few decades, various biomarker pathways have been identified that play a critical role in carcinogenesis such as Ras, NF-κB and DNA damage.

Survey of primary care physicians' views about breast and ovarian cancer screening for true BRCA1/2 non-carriers

Despite some controversy, true BRCA1/2 non-carriers are generally considered to be at an average risk for breast and ovarian cancer. Primary care physicians are then expected to encourage their non-carrier patients to adopt cancer screening practices appropriate to women of the same age in the general population. This study aimed to describe breast and ovarian cancer screening recommendations that primary care physicians would consider advisable for young true BRCA1/2 non-carriers. One hundred thirty-four family physicians and 123 gynecologists (response rate 45%) completed a cross-sectional mailed survey administered in the Province of Quebec, Canada. The survey included questions about basic genetic knowledge and screening recommendations for two fictitious cases (< 40 years), one carrier and one non-carrier, from a BRCA1/2 mutation-positive family. Screening exams considered advisable did not differ significantly between family physicians and gynecologists. More than 75% of physicians considered the cancer risks of true non-carriers to be comparable with that of the general population and 14% to be a little higher. Still, 53% would prescribe a biennial and or even an annual (27%) mammography to a non-carrier woman before the recommended starting age. Physician considerations of non-carriers' expectations or requests for screening were associated with more screening prescriptions. More than half of primary care physicians would recommend more mammography screenings than expected for a young true BRCA1/2 non-carrier. Personalized cancer risk assessment may help primary care physicians tailor screening of women from BRCA1/2 mutation-positive families and allow these women to make more informed choices regarding cancer risk management options.

Breast cancer risk assessment in patients who test negative for a hereditary cancer syndrome

BACKGROUND

The majority of women who undergo genetic testing due to a significant family history of breast cancer will receive a negative result. The purpose of this study was to calculate the lifetime risk of breast cancer in women undergoing genetic counseling who received an uninformative genetic test result.

METHODS

A retrospective chart review of mutation-negative women presenting to a cancer risk assessment clinic was performed. Lifetime risks of breast cancer were calculated using the Claus, Gail, and Tyrer-Cuzick risk assessment models.

RESULTS

Approximately half (51%) of the women were classified as high-risk by at least one risk assessment model. The Tyrer-Cuzick model identified the highest proportion (43.2%) of patients as high-risk. Four percent (n = 4) of the sample was considered high-risk by all three models.

CONCLUSIONS

More than half (51%) of women who underwent genetic counseling and received an uninformative negative genetic test result had a significantly elevated risk for the development of breast cancer. It is, therefore, imperative that women do not conclude that a negative genetic test result represents a lack of risk.

Genetic predisposition to colorectal cancer: syndromes, genes, classification of genetic variants and implications for precision medicine

This article reviews genes and syndromes associated with predisposition to colorectal cancer (CRC), with an overview of gene variant classification. We include updates on the application of preventive and therapeutic measures, focusing on the use of non-steroidal anti-inflammatory drugs (NSAIDs) and immunotherapy. Germline pathogenic variants in genes conferring high or moderate risk to cancer are detected in 6-10% of all CRCs and 20% of those diagnosed before age 50. CRC syndromes can be subdivided into nonpolyposis and polyposis entities, the most common of which are Lynch syndrome and familial adenomatous polyposis, respectively. In addition to known and novel genes associated with highly penetrant CRC risk, identification of pathogenic germline variants in genes associated with moderate-penetrance cancer risk and/or hereditary cancer syndromes not traditionally linked to CRC may have an impact on genetic testing, counseling, and surveillance. The use of multigene panels in genetic testing has exposed challenges in the classification of variants of uncertain significance. We provide an overview of the main classification systems and strategies for improving these. Finally, we highlight approaches for integrating chemoprevention in the care of individuals with genetic predisposition to CRC and use of targeted agents and immunotherapy for treatment of mismatch repair-deficient and hypermutant tumors. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Two Missense Variants Detected in Breast Cancer Probands Preventing BRCA2-PALB2 Protein Interaction

PALB2 (partner and localizer of BRCA2) was initially identified as a binding partner of BRCA2. It interacts also with BRCA1 forming a complex promoting DNA repair by homologous recombination. Germline pathogenic variants in BRCA1, BRCA2 and PALB2 DNA repair genes are associated with high risk of developing breast cancer. Mutation screening in these breast cancer predisposition genes is routinely performed and allows the identification of individuals who carry pathogenic variants and are at risk of developing the disease. However, variants of uncertain significance (VUSs) are often detected and establishing their pathogenicity and clinical relevance remains a central challenge for the risk assessment of the carriers and the clinical decision-making process. Many of these VUSs are missense variants leading to single amino acid substitutions, whose impact on protein function is uncertain. Typically, VUSs are rare and due to the limited genetic, clinical, and pathological data the multifactorial approaches used for classification cannot be applied. Thus, these variants can only be characterized through functional analyses comparing their effect with that of normal and mutant gene products used as positive and negative controls. The two missense variants BRCA2:c.91T >G (p.Trp31Gly) and PALB2:c.3262C >T (p.Pro1088Ser) were detected in two breast cancer probands originally ascertained at Breast Cancer Units of Institutes located in Milan and Bergamo (Northern Italy), respectively. These variants were located in the BRCA2-PALB2 interacting domains, were predicted to be deleterious by in silico analyses, and were very rare and clinically not classified. Therefore, we initiate to study their functional effect by exploiting a green fluorescent protein (GFP)-reassembly in vitro assay specifically designed to test the BRCA2-PALB2 interaction. This functional assay proved to be easy to develop, robust and reliable. It also allows testing variants located in different genes. Results from these functional analyses showed that the BRCA2:p.Trp31Gly and the PALB2:p.Pro1088Ser prevented the BRCA2-PALB2 binding. While caution is warranted when the interpretation of the clinical significance of rare VUSs is based on functional studies only, our data provide initial evidences in favor of the possibility that these variants are pathogenic.

Hereditary lobular breast cancer with an emphasis on E-cadherin genetic defect

Recent studies have reported germline CDH1 mutations in cases of lobular breast cancer (LBC) not associated with the classical hereditary diffuse gastric cancer syndrome. A multidisciplinary workgroup discussed genetic susceptibility, pathophysiology and clinical management of hereditary LBC (HLBC). The team has established the clinical criteria for CDH1 screening and results' interpretation, and created consensus guidelines regarding genetic counselling, breast surveillance and imaging techniques, clinicopathological findings, psychological and decisional support, as well as prophylactic surgery and plastic reconstruction. Based on a review of current evidence for the identification of HLBC cases/families, CDH1 genetic testing is recommended in patients fulfilling the following criteria: (A) bilateral LBC with or without family history of LBC, with age at onset <50 years, and (B) unilateral LBC with family history of LBC, with age at onset <45 years. In CDH1 asymptomatic mutant carriers, breast surveillance with clinical examination, yearly mammography, contrast-enhanced breast MRI and breast ultrasonography (US) with 6-month interval between the US and the MRI should be implemented as a first approach. In selected cases with personal history, family history of LBC and CDH1 mutations, prophylactic mastectomy could be discussed with an integrative group of clinical experts. Psychodecisional support also plays a pivotal role in the management of individuals with or without CDH1 germline alterations. Ultimately, the definition of a specific protocol for CDH1 genetic screening and ongoing coordinated management of patients with HLBC is crucial for the effective surveillance and early detection of LBC.