Clinical Implications of Germline Mutations in Breast Cancer - TP53

Purpose This review describes the prevalence of germline TP53 mutations, the risk of breast cancer and other cancers in mutation carriers and management implications for women with breast cancer and unaffected women. Methods Literature review of English language papers available through PubMed. Results Women who carry germline mutations in the TP53 gene have a very high risk of breast cancer of up to 85% by age 60 years. Most of these breast cancers are early onset with a median age at diagnosis of 34 years. Approximately 5–8% of women presenting with breast cancer under 30 years old have a germline TP53 gene mutation. Breast cancers in women with TP53 mutations are more likely to be hormone receptor positive and/or Her2 positive. Mastectomy is recommended over lumpectomy in TP53 mutation carriers who have breast cancer so that adjuvant breast radiotherapy can be avoided. Risk-reducing surgery should be considered due to the high contralateral breast cancer risk. Mutation carriers are at high risk of various childhood and adult-onset cancers with a very lifetime risk of malignancy, the commonest malignancies being breast cancer and soft tissue sarcoma. In unaffected female mutation carriers, MRI breast screening or risk-reducing surgery is recommended. The optimal surveillance for other cancers is currently unclear and should ideally be performed as part of a clinical trial. Conclusions Identifying a TP53 mutation in a gene panel test is a challenging result for the patient and clinician due to the high risk of second primaries and the lack of consensus about surveillance.KS holds an Academic Clinical Fellowship funded by the National Institute for Health Research (3090). MT is funded by the European Union Seventh Framework Program (2007–2013)/European Research Council (310018)

Incorporating truncating variants in PALB2, CHEK2, and ATM into the BOADICEA breast cancer risk model.

PURPOSE: The proliferation of gene panel testing precipitates the need for a breast cancer (BC) risk model that incorporates the effects of mutations in several genes and family history (FH). We extended the BOADICEA model to incorporate the effects of truncating variants in PALB2, CHEK2, and ATM. METHODS: The BC incidence was modeled via the explicit effects of truncating variants in BRCA1/2, PALB2, CHEK2, and ATM and other unobserved genetic effects using segregation analysis methods. RESULTS: The predicted average BC risk by age 80 for an ATM mutation carrier is 28%, 30% for CHEK2, 50% for PALB2, and 74% for BRCA1 and BRCA2. However, the BC risks are predicted to increase with FH burden. In families with mutations, predicted risks for mutation-negative members depend on both FH and the specific mutation. The reduction in BC risk after negative predictive testing is greatest when a BRCA1 mutation is identified in the family, but for women whose relatives carry a CHEK2 or ATM mutation, the risks decrease slightly. CONCLUSIONS: The model may be a valuable tool for counseling women who have undergone gene panel testing for providing consistent risks and harmonizing their clinical management. A Web application can be used to obtain BC risks in clinical practice (http://ccge.medschl.cam.ac.uk/boadicea/).Genet Med 18 12, 1190-1198.This work was funded by Cancer Research UK Grants C12292/A11174 and C1287/A10118. ACA is a Cancer Research UK Senior Cancer Research Fellow. This work was supported by the Governement of Canada through Genome Canada and the Canadian Institutes of Health Research, and the Ministère de l'enseignement supérieur, de la recherche, de la science et de la technologie du Québec through Génome Québec.This is the author accepted manuscript. The final version is available from Nature Publishing Group via http://dx.doi.org/10.1038/gim.2016.3

Biallelic somatic SMARCA4 mutations in small cell carcinoma of the ovary, hypercalcemic type (SCCOHT).

Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is a rare, aggressive tumor that primarily affects young women. SCCOHT has recently been identified as a monogenic disorder caused by germline and/or somatic SMARCA4 mutations. We describe a 15-year-old Caucasian female with a SCCOHT harboring a previously unreported somatic mutation in the SMARCA4 gene (c.1757delA; p.K586.fs) with loss of heterozygosity. No germline mutation was identified. Subsequent immunohistochemical staining confirmed loss of SMARCA4 protein. These molecular findings will aid with SCCOHT diagnosis through immunohistochemical staining for SMARCA4 and in the future may have implications for the management of this disease.This is the accepted manuscript. The final version is available at http://onlinelibrary.wiley.com/doi/10.1002/pbc.25279/abstract

Germ-line DICER1 mutations do not make a major contribution to the etiology of familial testicular germ cell tumours.

BACKGROUND: The RNase III enzyme DICER1 plays a central role in maturation of microRNAs. Identification of neoplasia-associated germ-line and somatic mutations in DICER1 indicates that mis-expression of miRNAs in cancer may result from defects in their processing. As part of a recent study of DICER1 RNase III domains in 96 testicular germ cell tumors, a single RNase IIIb domain mutation was identified in a seminoma. To further explore the importance of DICER1 mutations in the etiology of testicular germ cell tumors (TGCT), we studied germ-line DNA samples from 43 probands diagnosed with familial TGCT. FINDINGS: We carried out High Resolution Melting Curve Analysis of DICER1 exons 2-12, 14-19, 21 and 24-27. All questionable melt curves were subjected to confirmatory Sanger sequencing.Sanger sequencing was used for exons 13, 20, 22 and 23. Intron-exon boundaries were included in all analyses. We identified 12 previously reported single nucleotide polymorphisms and two novel single nucleotide variants. No likely deleterious variants were identified; notably no mutations that were predicted to truncate the protein were identified. CONCLUSIONS: Taken together with previous studies, the findings reported here suggest a very limited role for either germ-line or somatic DICER1 mutations in the etiology of TGCT.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Contribution of the PALB2 c.2323C>T [p.Q775X] founder mutation in well-defined breast and/or ovarian cancer families and unselected ovarian cancer cases of French Canadian descent.

BACKGROUND: The PALB2 c.2323C>T [p.Q775X] mutation has been reported in at least three breast cancer families and breast cancer cases of French Canadian descent and this has been attributed to common ancestors. The number of mutation-positive cases reported varied based on criteria of ascertainment of index cases tested. Although inherited PALB2 mutations are associated with increased risks of developing breast cancer, risk to ovarian cancer has not been fully explored in this demographically unique population. METHODS: We screened the PALB2 p.Q775X variant in 71 families with at least three cases of breast cancer (n=48) or breast and ovarian cancers (n=23) that have previously been found negative for at least the most common BRCA1 and BRCA2 mutations reported in the French Canadian population and in 491 women of French Canadian descent who had invasive ovarian cancer and/or low malignant potential tumors of the major histopathological subtypes. RESULTS: We identified a PALB2 p.Q775X carrier in a breast cancer family, who had invasive ductal breast carcinomas at 39 and 42 years of age. We also identified a PALB2 p.Q775X carrier who had papillary serous ovarian cystadenocarcinoma at age 58 among the 238 serous subtype ovarian cancer cases investigated, who also had breast cancer at age 52. CONCLUSION: Our findings, taken together with previous reports, support adding PALB2 c.2323C>T p.Q775X to the list of cancer susceptibility genes for which founder mutations have been identified in the French Canadian population.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Serum levels of mature microRNAs in DICER1-mutated pleuropulmonary blastoma.

DICER1 is a critical gene in the biogenesis of mature microRNAs, short non-coding RNAs that derive from either -3p or -5p precursor microRNA strands. Germline mutations of DICER1 are associated with a range of human malignancies, including pleuropulmonary blastoma (PPB). Additional somatic 'hotspot' mutations in the microRNA processing ribonuclease IIIb (RNase IIIb) domain of DICER1 are reported in cancer, and which affect microRNA biogenesis, resulting in a -3p mature microRNA strand bias. Here, in a germline (exon11 c.1806_1810insATTGA) DICER1-mutated PPB, we first confirmed the presence of an additional somatic RNase IIIb hotspot mutation (exon25 c.5425G>A [p.G1809R]) by conventional sequencing. Second, we investigated serum levels of mature microRNAs at the time of PPB diagnosis, and compared the findings with serum results from a comprehensive range of pediatric cancer patients and controls (n=52). We identified a panel of 45 microRNAs that were present at elevated levels in the serum at the time of PPB diagnosis, with a significant majority noted be derived from the -3p strand (P=0.013). In addition, we identified a subset of 10 serum microRNAs (namely miR-125a-3p, miR-125b-2-3p, miR-380-5p, miR-125b-1-3p, let-7f-2-3p, let-7a-3p, let-7b-3p, miR-708-3p, miR-138-1-3p and miR-532-3p) that were most abundant in the PPB case. Serum levels of two representative microRNAs, miR-125a-3p and miR-125b-2-3p, were not elevated in DICER1 germline-mutated relatives. In the PPB case, serum levels of miR-125a-3p and miR-125b-2-3p increased before chemotherapy, and then showed an early reduction following treatment. These microRNAs may offer future utility as serum biomarkers for screening patients with known germline DICER1 mutations for early detection of PPB, and for potential disease-monitoring in cases with confirmed PPB.We would like to thank the following for providing financial support: SPARKS (NC, MJM), Medical Research Council Fellowship (MJM), TD Bank/LDI scholarship (LdK), Alex’s Lemonade Stand Foundation (WDF), Cancer Research UK (NC) and European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement No. 310018 (MT).This is the final published version. It first appeared at http://www.nature.com/oncsis/journal/v3/n2/full/oncsis20141a.html

Whole exome sequencing study to detect germline pathogenic variants in PALB2 and other cancer-predisposing genes in CDH1 mutation negative diffuse gastric cancer families.

Background: Germline pathogenic variants in the E-cadherin gene (CDH1) are strongly associated with the development of hereditary diffuse gastric cancer (HDGC) syndrome. The risk assessment and management of HDGC families that do not carry a CDH1 variant is limited. It is therefore difficult for such families to make informed choices about surveillance and risk reducing surgery. This study aimed to identify new candidate genes for HDGC predisposition in families with no detected pathogenic CDH1 variants (CDH1-NPV). Methods: Whole exome sequencing (WES) was performed on DNA extracted from blood obtained as part of the Familial Gastric Cancer Study. Analysis was performed across 39 individuals (28 affected and 11 unaffected) from 22 CDH1-NPV families that fulfil the international criteria for HDGC. Genes with loss-of-function variants were prioritised using gene interaction analysis to identify clusters of genes that could be involved in HDGC predisposition. Findings: Protein-affecting germline variants were identified in known cancer predisposition genes or lesser studied DNA repair genes in six HDGC families. A frameshift deletion within PALB2 was found in a family with a history of gastric and breast cancer. Two MSH2 variants were identified, one frameshift insertion and one previously described start loss, in unrelated affected individuals. One family was identified with a unique combination of variants in DNA repair genes ATR and NBN. A missense variant and a splice acceptor variant were seen in two unrelated families in DNA repair gene RECQL5. Interpretation: This study supports the role of known cancer predisposition gene PALB2 in the HDGC syndrome. It also puts forward new candidates in relation to HDGC risk within CDH1-NPV families. Funding: This work has been funded and supported by the UK Medical Research Council (MRC)/Sackler programme, the European Union Seventh Framework Program (2007–2013)/European Research Council (310018), the National Institute for Health Research Cambridge Biomedical Research Centre and the Experimental Cancer Medicine Centre and Cancer Research UK

Cancer risks associated with germline PALB2 pathogenic variants - an international study of 524 families

PURPOSE To estimate age-specific relative and absolute cancer risks for breast cancer, and to estimate risks of ovarian, pancreatic, male breast, prostate, and colorectal cancers associated with germline PALB2 pathogenic variants (PVs) as these risks have not been extensively characterized. METHODS We analysed data from 524 families with PALB2 PVs from 21 countries. Complex segregation analysis was used to estimate relative risks (RRs, relative to country-specific population incidences) and absolute risks of cancers. The models allowed for residual familial aggregation of breast and ovarian cancer and were adjusted for the family-specific ascertainment schemes. RESULTS We found associations between PALB2 PVs and risk of female breast cancer (RR=7.18; 95% CI: 5.82-8.85, p=6.5×10-76), ovarian cancer (RR=2.91; 95% CI: 1.40-6.04, p=4.1×10-3), pancreatic cancer (RR=2.37; 95% CI: 1.24-4.50; p=8.7×10-3), and male breast cancer (RR=7.34, 95% CI: 1.28-42.18, p=2.6×10-2). There no evidence for increased risks of prostate or colorectal cancer. The breast cancer RRs declined with age (p-trend=2.0×10-3). After adjusting for family-ascertainment, breast cancer risk estimates based on multiple case families were similar to the estimates from families ascertained through population-based studies (p-difference=0.41). Based on the combined data, the estimated risks to age 80 years were 53% (95% CI: 44-63%) for female breast cancer, 5% (95% CI: 2-10%) for ovarian cancer, 2-3% (95% CI: females: 1-4%; males: 2-5%) for pancreatic cancer, and 1% (95% CI: 0.2-5%) for male breast cancer. CONCLUSION These results confirm PALB2 as a key breast cancer susceptibility gene and establish substantial associations between germline PALB2 PVs and ovarian, pancreatic, and male breast cancers. These findings will facilitate incorporation of PALB2 into risk prediction models and optimise the clinical cancer risk management of PALB2 PV carriers.ERC, CRUK, NIH, NIH

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

Purpose BRCA1/BRCA2 predictive test negatives are proven noncarriers of a BRCA1/BRCA2 mutation that is carried by their relatives. The risk of developing breast cancer (BC) or epithelial ovarian cancer (EOC) in these women is uncertain. The study aimed to estimate risks of invasive BC and EOC in a large cohort of BRCA1/BRCA2 predictive test negatives. Methods We used cohort analysis to estimate incidences, cumulative risks, and standardized incidence ratios (SIRs). Results A total of 1,895 unaffected women were eligible for inclusion in the BC risk analysis and 1,736 in the EOC risk analysis. There were 23 incident invasive BCs and 2 EOCs. The cumulative risk of invasive BC was 9.4% (95% confidence interval (CI) 5.9-15%) by age 85 years and the corresponding risk of EOC was 0.6% (95% CI 0.2-2.6%). The SIR for invasive BC was 0.93 (95% CI 0.62-1.40) in the overall cohort, 0.85 (95% CI 0.48-1.50) in noncarriers from BRCA1 families, and 1.03 (95% CI 0.57-1.87) in noncarriers from BRCA2 families. The SIR for EOC was 0.79 (95% CI 0.20-3.17) in the overall cohort. Conclusion Our results did not provide evidence for elevated risks of invasive BC or EOC in BRCA1/BRCA2 predictive test negatives. Genetics in Medicine advance online publication, 22 March 2018; doi:10.1038/gim.2018.44

Caveat Emptor: The Perils of Panel Testing in Hereditary Breast Cancer.

In a recent issue of Journal of Clinical Oncology, Beitsch et al1 argue for expanded panel testing in all patients with a diagnosis of breast cancer. Their argument rests on the finding that of patients who met National Comprehensive Cancer Network guidelines, 9.39% had a pathogenic/likely pathogenic (P/LP) variant, whereas of those patients who did not meet National Comprehensive Cancer Network guidelines, 7.9% had a P/LP variant. These figures, however, include many variants in genes that have no definite proven association with an increased risk of breast cancer.2 These results may thus represent incidental findings that could equally be found in an unselected population and will not inform the management of their disease. Indeed, even at below the expected carrier frequency of one in 50, monoallelic variants in the recessively inherited gene MUTYH account for a full 20% of the reported findings in patients who did not meet NCCN guidelines. These findings are not pertinent and amount to population screening