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    72P Impact of extended panel of genes for germline cancer testing
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    e13509 Background: Hereditary cancer accounts for approximately 10% of all cancers. An estimated 15-20% of all cancer patients have positive family history. However, until recently mutations in highly penetrant genes were only identified in approximately 20% of high-risk families. Technological advances in DNA sequencing, commonly designated as “Next Generation Sequencing-NGS” allowed to identify new genes responsible for the missing heritability, allowing the application of this knowledge in the diagnostic setting. Methods: Between 2015 and 2017, 276 patients were tested at two institutions in Dubai, UAE for BRCA1 and BRCA2 genes and the common CHEK2 c.1100delC mutation. In 2017, testing was extended to include 33 genes for 89 patients tested. Testing for all 276 patients was conducted at a single laboratory with testing criteria based on NCCN guidelines. Results: At the time of testing, median age was 44 years (range 26–72 years) with the majority of patients diagnosed with breast cancer. Patients tested were from a diverse ethnic group the majority of whom were from the Middle East and Asia pacific region. 24/276 (8.7%) had a pathogenic variant identified in the BRCA (n = 13), BRCA2 (n = 8) or c.1100delC in CHEK2 (n = 3) gene and 30 (10.8%) patients had a VUS in one of the three genes. Of the 89 patients tested with the 33 gene panel, additional pathogenic variants were identified in 7 (7.8%) patients involving the MUTYH (n = 4), RAD51C (n = 1), RAD50 (n = 1) and PALB2 (n = 1) genes and at least one VUS was reported in 35 (39%) patients. The most commonly mutated genes across the whole cohort were BRCA1 and BRCA2, accounting for 55% of the mutations identified. Two (11%) of the mutations identified were large genomic rearrangements of several exons of the BRCA1 and RAD51C genes. Conclusions: Our results support the clinical significance of analysis of a panel of genes involved in hereditary cancer predisposition. In our series, pathogenic variants were identified in all but one case in genes for which enough data has been collected allowing for the formulation of clinical management guidelines. These patients have therefore received results which will alter their clinical management.
    CHEK2
    MUTYH
    PALB2
    Breast cancer (BC) in men is rare and genetic predisposition is likely to play a relevant role in its etiology. Inherited mutations in BRCA1/2 account for about 13% of all cases and additional genes that may contribute to the missing heritability need to be investigated. In our study, a well‐characterized series of 523 male BC (MBC) patients from the Italian multicenter study on MBC, enriched for non‐ BRCA1/2 MBC cases, was screened by a multigene custom panel of 50 cancer‐associated genes. The main clinical‐pathologic characteristics of MBC in pathogenic variant carriers and non‐carriers were also compared. BRCA1/2 pathogenic variants were detected in twenty patients, thus, a total of 503 non‐ BRCA1/2 MBC patients were examined in our study. Twenty‐seven of the non‐ BRCA1/2 MBC patients were carriers of germline pathogenic variants in other genes, including two APC p.Ile1307Lys variant carriers and one MUTYH biallelic variant carrier. PALB2 was the most frequently altered gene (1.2%) and PALB2 pathogenic variants were significantly associated with high risk of MBC. Non‐ BRCA1/2 pathogenic variant carriers were more likely to have personal ( p = 0.0005) and family ( p = 0.007) history of cancer. Results of our study support a central role of PALB2 in MBC susceptibility and show a low impact of CHEK2 on MBC predisposition in the Italian population. Overall, our data indicate that a multigene testing approach may benefit from appropriately selected patients with implications for clinical management and counseling of MBC patients and their family members.
    PALB2
    CHEK2
    MUTYH
    Male Breast Cancer
    Missing heritability problem
    Genetic predisposition
    Candidate gene
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    e16276 Background: Pancreatic cancer is one of the most fatal malignancies. It accounts for 2% of all cancers and 5% of cancer-related deaths. Hence, it is essential to identify pancreatic cancer at an earlier stage to improve outcomes. A variety of hereditary cancer syndromes have been associated with an increased risk of developing pancreatic cancer, and these individuals may benefit from surveillance plans. PARP inhibitor therapy is currently being applied as precision medicine to pancreatic cancer patients harboring germline variant in the Homologous recombination repair (HRR) genes. Our aim was to determine the prevalence of germline pathogenic/likely pathogenic variants in cancer predisposing genes in patients with pancreatic cancer. Methods: In total, 113 patients diagnosed with pancreatic cancer were referred to our laboratory for genetic testing. The analysis of 52 genes involved in hereditary cancer predisposition was performed using a NGS approach. Results: A germline pathogenic/likely pathogenic variant was identified in 20% of patients analyzed. Among individuals with germline pathogenic/likely pathogenic variants, 60% had a positive finding in a pancreatic cancer susceptibility gene; ATM (20%), BRCA1 (20%), BRCA2 (12%), CDKN2A (4%), PALB2 (4%) while 40% carried positive findings in other cancer susceptibility genes. More specifically, in CHEK2 (16%), MRE11 (4%), RAD50 (4%), RAD51C (4%), MUTYH (8%) and NTLH1 (4%). Notably, 84% of pathogenic variants were identified in genes associated with the HRR pathway ( ATM, BRCA1, BRCA2, CHEK2, MRE11, PALB2, RAD50 and RAD51C). Conclusions: Our results indicate that multigene genetic testing is meaningful for pancreatic cancer patients as in 20% of tested individuals we identified findings associated with pancreatic or other cancer predisposition. Moreover, pathogenic/likely pathogenic variants in HRR genes, were identified in 16.6% patients and these patients might benefit from targeted treatments, such as PARP inhibitors or platinum-based treatment.
    PALB2
    MUTYH
    CHEK2
    Genetic predisposition
    Abstract Genetic testing in the modern era increasingly examines multiple genes using next generation technologies. Most assays include the high penetrance genes, which confer lifetime breast cancer risk greater than 5-fold, include BRCA1/2, TP53, CDH1 and PALB2. Moderate penetrance genes are associated with lifetime breast cancer risk in the range of 2-3 fold, and include ATM, NF1, CHEK2 (mutation-specific) and NBN, with BARD1 and others potentially joining the group. Substantial data has emerged from studies of women with BRCA1/2 mutations, evaluating the performance of screening technologies, such as mammogram, breast MRI and ultrasound, and the efficacy of risk-reducing breast and ovarian/fallopian tube surgical procedures. Guidelines exist in the NCCN (US) and ESMO guidelines in Europe, among others, trying to provide recommendations for the age at which to initiate screening or undergo risk-reducing salpingo-oophorectomies, for example. Data are increasing on the moderate penetrance genes but there is still much reliance on extrapolation from the high-penetrance genes, which should be done thoughtfully. One approach is to estimate the age at which lifetime breast cancer risk equals the risk from a high penetrance gene when screening is to begin and initiate imaging surveillance at that time. For example, initiation of annual breast imaging would be at age 40 for ATM (RR 2.8) instead of age 25 as is done for BRCA1/2 or age 20 as for TP53. However, there are no data that this is the correct age at which to initiate screening, so this practical suggestion must meet criteria for reasonableness as well as effectiveness. Other source of data may include more precise gene-specific risk estimates from focused genetic epidemiology studies, and ongoing data from studies of prospectively identified mutation carriers. Further understanding of the mechanisms of carcinogenicity for mutation carriers may also help to provide insights that can guide therapeutic and preventive approaches. For example, the work on RANK ligand by Lindeman et al has led to the development of a definitive breast cancer prevention trial examining the RANK-Ligand inhibitor Denosumab in BRCA1 mutation carriers, entitled BRCA-P, being led by C. Singer of the ABCSG and Dr. Lindeman, and to be conducted in sites around the world. Other approaches are in development and will be discussed. Citation Format: Garber JE. Managing increased breast cancer risk based on high and moderate penetrance gene mutations [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr ES2-3.
    Penetrance
    CHEK2
    PALB2
    23 Background: New technologies for identifying hereditary predisposition to breast cancer have led to the discovery of novel genes associated with cancer risk. This has prompted re-evaluation of patients who previously tested negative for BRCA1/2 gene mutations, with a possibility of discovering new genes which may impact management. This study reports on the results of retesting patients who previously were negative for BRCA1/2. Methods: Patients who tested negative for BRCA1/2 mutations who had significant personal and family history were referred back to the Cancer Genetics Center between February 1, 2012 and May 30, 2105 for discussion of additional testing. A detailed personal and family history was reviewed, and patients were counseled about the genetics and clinical implications of panel testing for multiple breast cancer genes. Panel testing using next generation sequencing technologies was ordered. Patients were seen in follow up for discussion of results and management. Results: A total of 12 pathogenic mutations were identified during the study period. The genes and frequencies of these mutations were: CHEK2(3), PALB2(3), ATM(2), APC(1), BARD(1), CDH(1), MUTYH(1). There were 33 variants of undetermined significance(VUS) in 27 patients. 5 of these were seen in patients with a known pathogenic mutation; 3 others were later classified as benign. The frequencies of these VUSs were: ATM (9), PALB2(3), BARD1 (3), PTEN(3), PMS2(3), MSH6(2), CHEK2 (1), MYH(1), RAD51(1), BRIP1(2), NF1(1), BMPR1A(1). Of the 46 patients who had their initial BRCA testing and repeat panel testing between February 1, 2012 and May 30, 2015, 6 (13%) tested positive for a pathogenic mutation. Conclusions: This study demonstrates the feasibility and potential clinical benefit of retesting individuals who previously tested negative for BRCA1/2 mutation. This approach had a significant management impact on patients and their families, with a 13% detection rate of pathogenic mutations. The success of retesting is predicated upon an infrastructure of provider and patient education, pre and post genetic counseling and serves as a model for other centers.
    CHEK2
    PALB2
    MUTYH
    MSH6
    PMS2
    Abstract 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.
    Penetrance
    Citations (26)
    Abstract We studied the penetrance and clinical outcomes of seven breast cancer susceptibility genes ( BRCA1, BRCA2, TP53, CHEK2, ATM, PALB2 and PTEN ) in almost 25,000 participants unselected for personal or family history of breast cancer. We identified 420 participants with pathogenic or likely pathogenic variants, and 147 were women who did not previously know their genetic results. Out of these 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 18-44%, depending on the gene. Within the first twelve months after genetic results disclosure, 42% of women had taken actions related to their genetic results and two new breast cancer cases were identified. 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 healthcare through early diagnosis and preventative screening.
    CHEK2
    Penetrance
    PALB2