Journal of Medical Genetics

Evidence for pathogenicity of BRCA2 c.8351G>A p.(Arg2784Gln) and the challenges in classification of pathogenic variants with reduced penetrance

Background The BRCA2 c.8351G>A p.(Arg2784Gln) variant has long been classified as a variant of uncertain significance (VUS) due to conflicting evidence used in variant classification. This study aims to clarify its pathogenicity and associated risks for breast and ovarian cancer. Methods This study was conducted by the international Evidence-based Network for the Interpretation of Germline Mutant Alleles consortium. We collected data from 29 informative families with this variant. Co-segregation likelihood ratios (LRs) were calculated using the full-likelihood method to assess pathogenicity, and cancer risks were estimated with modified segregation analysis. Results Co-segregation analysis using a grid search across scaled penetrance levels for BRCA2 truncating variants yielded the strongest evidence in favour of pathogenicity, with LR maximised at approximately 20% of full penetrance (LR=11.026). Furthermore, estimated breast cancer risks were markedly higher for early onset breast cancer; women diagnosed at <50 years had a HR of 4.5, compared with a HR of 1.65 for women diagnosed at ≥50 years. The estimated lifetime risks were 25% for breast cancer and 6% for ovarian cancer. Evidence of pathogenicity was also supported by the presence of the variant allele in two patients with Fanconi anaemia. Conclusions Our results indicate that BRCA2 c.8351G>A p.(Arg2784Gln) has a disease-causing effect, with reduced penetrance, similar to other pathogenic variants in moderate risk breast cancer genes such as ATM and CHEK2 . We also provide risk-adapted recommendations for clinical management. Importantly, one should be aware of a reduced penetrance as the underlying reason for conflicting results among pieces of evidence used for variant classification.

Impact of NICE Guideline NG241 ‘Ovarian Cancer: identifying and managing familial and genetic risk’ on a regional NHS family history and clinical genetics service

Background NICE Guideline NG241: identifying and managing familial and genetic risk of ovarian cancer (OC) was published by the National Institute for Health and Care Excellence (NICE) in March 2024. NG241 advises germline genetic testing of genes predisposing to OC in unaffected individuals with an OC family history at different mutation likelihood thresholds depending on age and sex, ranging from 2% to 10% likelihood of finding a germline pathogenic variant (GPV). Prior to implementation of NG241, updates to the NHS England National Genomic Test Directory would be required. Clinical genetics services have to consider equity of access to assessment and testing across all familial cancer types, best use of their limited resources and other factors such as complexity of delivery of clinical pathways. Methods We analysed data from 8011 patients who provided digital family histories to the South West Thames Centre for Genomics between October 2019 and June 2024. Results We estimate 527/782 (68%) females and 28/77 (36%) males would meet test criteria for NICE NG241. We estimate we would reject 2919/5485 (53%) females and 135/1208 (11%) males with the same likelihood of carrying a GPV, but with a breast cancer rather than OC family history. Testing the familial OC cohort at a universal 5% threshold in OC families would detect ~11 carriers for 229 tests compared with ~8 carriers for 278 tests following NG241 criteria. Conclusion Our data highlight additional factors needing to be considered before the NICE Guideline NG241 can be implemented by regional genetics services.

The NHS England Jewish BRCA Testing Programme: overview after first year of implementation (2023–2024)

Background The NHS Jewish BRCA Testing Programme is offering germline BRCA1 and BRCA2 genetic testing to people with ≥1 Jewish grandparent. Who have an increased likelihood of having an Ashkenazi Jewish (AJ) founder germline pathogenic variant (gPV) compared with the general population. Testing is offered via a self-referral, home-based saliva sampling pathway, supported by a genetic counsellor telephone helpline. A first-of-its-kind in the United Kingdom (UK) for population genetic testing, outside of research. Methods We reviewed data from germline testing of 5389 people who registered during the soft-launch phase (January 2023–January 2024) and their families to observe trends in uptake and outcomes of testing. Results Of the 5389 self-referrals, 4339 (80.5%) consented to testing. Of those with results returned, 2.3% (98/4,274) had a gPV (89.8% AJ founder and 10.2% non-AJ founder). Notably, the detection rate was higher in men (42/790, 5.3%) compared with women (56/3484, 1.6%), with the proportion reporting known BRCA variants within the family prior to consent also significantly increased (13.1% compared with 9.2%, respectively). Conclusion Overall detection rates of gPVs are similar to those reported elsewhere from Jewish population testing. The pathway, particularly for males, may attract uptake of testing by those previously aware of familial gPVs.

Validation of the BOADICEA model in a prospective cohort of BRCA1/2 pathogenic variant carriers

Background No validation has been conducted for the BOADICEA multifactorial breast cancer risk prediction model specifically in BRCA1/2 pathogenic variant (PV) carriers to date. Here, we evaluated the performance of BOADICEA in predicting 5-year breast cancer risks in a prospective cohort of BRCA1/2 PV carriers ascertained through clinical genetic centres. Methods We evaluated the model calibration and discriminatory ability in the prospective TRANsIBCCS cohort study comprising 1614 BRCA1 and 1365 BRCA2 PV carriers (209 incident cases). Study participants had lifestyle, reproductive, hormonal, anthropometric risk factor information, a polygenic risk score based on 313 SNPs and family history information. Results The full multifactorial model considering family history together with all other risk factors was well calibrated overall (E/O=1.07, 95% CI: 0.92 to 1.24) and in quintiles of predicted risk. Discrimination was maximised when all risk factors were considered (Harrell’s C-index=0.70, 95% CI: 0.67 to 0.74; area under the curve=0.79, 95% CI: 0.76 to 0.82). The model performance was similar when evaluated separately in BRCA1 or BRCA2 PV carriers. The full model identified 5.8%, 12.9% and 24.0% of BRCA1/2 PV carriers with 5-year breast cancer risks of <1.65%, <3% and <5%, respectively, risk thresholds commonly used for different management and risk-reduction options. Conclusion BOADICEA may be used to aid personalised cancer risk management and decision-making for BRCA1 and BRCA2 PV carriers. It is implemented in the free-access CanRisk tool ( https://www.canrisk.org/ ).

Pathogenic variant detection rate varies considerably in male breast cancer families and sporadic cases: minimal additional contribution beyond BRCA2, BRCA1 and CHEK2

Background Male breast cancer (MBC) affects around 1 in 1000 men and is known to have a higher underlying component of high and moderate risk gene pathogenic variants (PVs) than female breast cancer, particularly in BRCA2. However, most studies only report overall detection rates without assessing detailed family history. Methods We reviewed germline testing in 204 families including at least one MBC for BRCA1, BRCA2, CHEK2 c.1100DelC and an extended panel in 93 of these families. Individuals had MBC (n=118), female breast cancer (FBC)(n=80), ovarian cancer (n=3) or prostate cancer-(n=3). Prior probability of having a BRCA1/2 PV was assessed using the Manchester Scoring System (MSS). Results In the 204 families, BRCA2 was the major contributor, with 51 (25%) having PVs, followed by BRCA1 and CHEK2, with five each (2.45%) but no additional PVs identified, including in families with high genetic likelihood on MSS. Detection rates were 85.7% (12/14) in MSS ≥40 and 65.5% with MSS 30–39 but only 12.8% (6/47) for sporadic breast cancer. PV rates were low and divided equally between BRCA1/2 and CHEK2. Conclusion As expected, BRCA2 PVs predominate in MBC families with rates 10-fold those in CHEK2 and BRCA1. The MSS is an effective tool in assessing the likelihood of BRCA1/2 PVs.

Clinical implications of VUS reclassification in a single-centre series from application of ACMG/AMP classification rules specified for BRCA1/2

Background BRCA1/2 testing is crucial to guide clinical decisions in patients with hereditary breast/ovarian cancer, but detection of variants of uncertain significance (VUSs) prevents proper management of carriers. The ENIGMA (Evidence-based Network for the Interpretation of Germline Mutant Alleles) BRCA1/2 Variant Curation Expert Panel (VCEP) has recently developed BRCA1/2 variant classification guidelines consistent with ClinGen processes, specified against the ACMG/AMP (American College of Medical Genetics and Genomics/Association for Molecular-Pathology) classification framework. Methods The ClinGen-approved BRCA1/2-specified ACMG/AMP classification guidelines were applied to BRCA1/2 VUSs identified from 2011 to 2022 in a series of patients, retrieving information from the VCEP documentation, public databases, literature and ENIGMA unpublished data. Then, we critically re-evaluated carrier families based on new results and checked consistency of updated classification with main sources for clinical interpretation of BRCA1/2 variants. Results Among 166 VUSs detected in 231 index cases, 135 (81.3%) found in 197 index cases were classified by applying BRCA1/2-specified ACMG/AMP criteria: 128 (94.8%) as Benign/Likely Benign and 7 (5.2%) as Pathogenic/Likely Pathogenic. The average time from the first report as ‘VUS’ to classification using this approach was 49.4 months. Considering that 15 of these variants found in 64 families had already been internally reclassified prior to this work, this study provided 121 new reclassifications among the 151 (80.1%) remaining VUSs, relevant to 133/167 (79.6%) families. Conclusions These results demonstrated the effectiveness of new BRCA1/2 ACMG/AMP classification guidelines for VUS classification within a clinical cohort, and their important clinical impact. Furthermore, they suggested a cadence of no more than 3 years for regular review of VUSs, which however requires time, expertise and resources.

Risk-reducing decisions regarding germline BRCA pathogenic variant: focusing on the timing of genetic testing and RRSO

Background In Japan, the public insurance policy was revised in 2020 to cover hereditary breast and ovarian cancer (HBOC), including genetic testing and surveillance, for patients with breast cancer (BC). Consequently, the demand for risk-reducing salpingo-oophorectomy (RRSO) has increased. This study aimed to clarify the changes in the demand and timing of genetic testing and RRSO associated with public insurance coverage for HBOC in Japan. Methods This retrospective analysis included 350 women with germline BRCA (gBRCA) pathogenic variants (PVs) who had visited gynaecologists; they received gBRCA genetic testing at 45.1±10.6 (20–74) years. The use of medical testing and preventive treatment was compared between the preinsurance and postinsurance groups using Mann-Whitney U and Fisher’s exact tests. Results The findings indicate that RRSO rates doubled from 31.4% to 62.6% among patients with gBRCA-PV. The implementation rate was 32.4% among unaffected carriers and 70.3% among BC-affected patients. Younger patients received genetic testing with significantly shorter intervals between BC diagnosis and genetic testing and between genetic testing and RRSO. Conclusion Overall, the insurance coverage for HBOC patients with BC has increased the frequency of RRSO in Japan. However, a comparison between the number of probands and family members indicated that the diagnosis among family members is inadequate. The inequality in the use of genetic services by socioeconomic groups is an issue of further concern.

Estimating cancer risk in carriers of Lynch syndrome variants in UK Biobank

Background Lynch syndrome (LS) is an inherited cancer predisposition syndrome caused by genetic variants affecting DNA mismatch repair (MMR) genes MLH1 , MSH2 , MSH6 and PMS2 . Cancer risk in LS is estimated from cohorts of individuals ascertained by individual or family history of cancer, which may upwardly bias estimates. Methods 830 carriers of pathogenic or likely pathogenic ( path_MMR ) MMR gene variants classified by InSiGHT were identified in 454 756 UK Biobank (UKB) participants using whole-exome sequence. Nelson-Aalen survival analysis was used to estimate cumulative incidence of colorectal, endometrial and breast cancer (BC). Results Cumulative incidence of colorectal and endometrial cancer (EC) by age 70 years was elevated in path_MMR carriers compared with non-carriers (colorectal: 11.8% (95% confidence interval (CI): 9.5% to 14.6%) vs 1.7% (95% CI: 1.6% to 1.7%), endometrial: 13.4% (95% CI: 10.2% to 17.6%) vs 1.0% (95% CI: 0.9% to 1.0%)), but the magnitude of this increase differed between genes. Cumulative BC incidence by age 70 years was not elevated in path_MMR carriers compared with non-carriers (8.9% (95% CI: 6.3% to 12.4%) vs 7.5% (95% CI: 7.4% to 7.6%)). Cumulative cancer incidence estimates in UKB were similar to estimates from the Prospective Lynch Syndrome Database for all genes and cancers, except there was no evidence for elevated EC risk in carriers of pathogenic PMS2 variants in UKB. Conclusion These results support offering incidentally identified carriers of any path_MMR surveillance to manage colorectal cancer risk. Incidentally identified carriers of pathogenic variants in MLH1 , MSH2 and MSH6 would also benefit from interventions to reduce EC risk. The results suggest that BC is not an LS-related cancer.

Comprehensive evidence for the pathogenicity of the BRCA2 c.7847C>T (p.Ser2616Phe) variant specific to the Japanese population

Background The BRCA2 c.7847C>T (p.Ser2616Phe) variant is specific to the Japanese population and has long remained a variant of uncertain significance. Because BRCA1/2 genetic testing serves as a companion diagnostic for poly (ADP-ribose) polymerase inhibitor therapy in Japan, unresolved classification has limited access to targeted treatment. Methods We conducted a nationwide study using the national Hereditary Breast and Ovarian Cancer registry. Pathogenicity was assessed through quantitative cosegregation analysis, a systematic review of functional and clinical evidence and evaluation of variant frequency in population databases. Evidence was integrated using the ClinGen ENIGMA BRCA1/2 Variant Curation Expert Panel framework. Results We identified 44 carriers from 35 distinct Japanese families. Quantitative cosegregation analysis yielded a combined likelihood ratio of approximately 60, satisfying the PP1_Strong criterion. This was supported by robust evidence from multiple functional studies, including Mixed-All-Nominated-in-One-BRCA, homology-directed repair and saturation genome editing assays (PS3) and a reported case of Fanconi anaemia (PM3_Moderate). This variant is rare, with an allele frequency of 6.20×10 –7 in gnomAD and 1.06×10 –4 in ToMMo 61KJPN (PM2_Supporting). Although the BayesDel noAF score met the benign criterion (BP4), other in silico tools indicated deleterious effects. In total, the accumulated evidence reached 10 points, corresponding to an estimated odds of pathogenicity of 895:1, exceeding the ‘Pathogenic’ threshold. Conclusion By integrating newly collected genetic data with functional and clinical evidence, we provide robust support for reclassifying the BRCA2 c.7847C>T (p.Ser2616Phe) variant as ‘Pathogenic’. This reclassification is crucial for ensuring that eligible Japanese patients gain access to appropriate targeted therapies.

Lynch syndrome diagnostic testing pathways in endometrial cancers: a nationwide English registry-based study

Background For female patients with Lynch syndrome (LS), endometrial cancer (EC) is often their first cancer diagnosis. A testing pathway of somatic tumour testing triage followed by germline mismatch repair (MMR) gene testing is an effective way of identifying the estimated 3% of EC caused by LS. Methods A retrospective national population-based observational study was conducted using comprehensive national data collections of functional, somatic and germline MMR tests available via the English National Cancer Registration Dataset. For all EC diagnosed in 2019, the proportion tested, median time to test, yield of abnormal results and factors influencing testing pathway initiation were examined. Results There was an immunohistochemistry (IHC) or microsatellite instability (MSI) test recorded for 17.8% (1408/7928) of patients diagnosed with EC in 2019. Proportions tested varied by Cancer Alliance and age. There was an MLH1 promoter hypermethylation test recorded for 43.1% (149/346) of patients with MLH1 protein IHC loss or MSI. Of patients with EC eligible from tumour-testing, 25% (26/104) had a germline MMR test recorded. Median time from cancer diagnosis to germline MMR test was 315 days (IQR 222–486). Conclusion This analysis highlights the regional variation in recorded testing, patient attrition, delays and missed opportunities to diagnose LS, providing an informative baseline for measuring the impact of the national guidance from the National Institute for Health and Care Excellence on universal reflex LS testing in EC, implemented in 2020.

Advances in genetic technologies result in improved diagnosis of mismatch repair deficiency in colorectal and endometrial cancers

Background Testing cancers for mismatch repair deficiency (dMMR) by immunohistochemistry (IHC) is a quick and inexpensive means of triaging individuals for germline Lynch syndrome testing. The aim of this study was to evaluate tumour dMMR and the prevalence of Lynch syndrome in patients referred to the Manchester Centre for Genomic Medicine, which serves a population of 5.6 million. Methods Tumour testing used IHC for MMR proteins with targeted BRAF and MLH1 promotor methylation testing followed by germline mutation and somatic testing as appropriate. Results In total, 3694 index tumours were tested by IHC (2204 colorectal cancers (CRCs), 739 endometrial cancers (ECs) and 761 other), of which 672/3694 (18.2%) had protein loss, including 348 (9.4%) with MLH1 loss. MLH1 loss was significantly higher for 739 ECs (15%) vs 2204 CRCs (10%) (p=0.0003) and was explained entirely by higher rates of somatic MLH1 promoter hypermethylation (87% vs 41%, p<0.0001). Overall, 65/134 (48.5%) patients with MLH1 loss and no MLH1 hypermethylation or BRAF c.1799T>A had constitutional MLH1 pathogenic variants. Of 456 patients with tumours showing loss of MSH2/MSH6, 216 (47.3%) had germline pathogenic variants in either gene. Isolated PMS2 loss was most suggestive of a germline MMR variant in 19/26 (73%). Of those with no germline pathogenic variant, somatic testing identified likely causal variants in 34/48 (71%) with MLH1 loss and in MSH2/MSH6 in 40/47 (85%) with MSH2/MSH6 loss. Conclusions Reflex testing of EC/CRC leads to uncertain diagnoses in many individuals with dMMR following IHC but without germline pathogenic variants or MLH1 hypermethylation. Tumour mutation testing is effective at decreasing this by identifying somatic dMMR in >75% of cases.

Association between genetic polymorphisms and endometrial cancer risk: a systematic review

Introduction Endometrial cancer is one of the most commonly diagnosed cancers in women. Although there is a hereditary component to endometrial cancer, most cases are thought to be sporadic and lifestyle related. The aim of this study was to systematically review prospective and retrospective case–control studies, meta-analyses and genome-wide association studies to identify genomic variants that may be associated with endometrial cancer risk. Methods We searched MEDLINE, Embase and CINAHL from 2007 to 2019 without restrictions. We followed PRISMA 2009 guidelines. The search yielded 3015 hits in total. Following duplicate exclusion, 2674 abstracts were screened and 453 full-texts evaluated based on our pre-defined screening criteria. 149 articles were eligible for inclusion. Results We found that single nucleotide polymorphisms (SNPs) in HNF1B, KLF, EIF2AK, CYP19A1, SOX4 and MYC were strongly associated with incident endometrial cancer. Nineteen variants were reported with genome-wide significance and a further five with suggestive significance. No convincing evidence was found for the widely studied MDM2 variant rs2279744. Publication bias and false discovery rates were noted throughout the literature. Conclusion Endometrial cancer risk may be influenced by SNPs in genes involved in cell survival, oestrogen metabolism and transcriptional control. Larger cohorts are needed to identify more variants with genome-wide significance.

Economic evaluation of personalised versus conventional risk assessment for women who have undergone testing for hereditary breast and ovarian cancer genes: a modelling study

Background The management of women with germline pathogenic variants (GPVs) in breast (BC) and ovarian cancer (OC) susceptibility genes is focused on surveillance and risk-reducing surgery/medication. Most women are assigned an average range of risk and treated accordingly, but it is possible to personalise this. Here, we explore the economic impact of risk personalisation. Method We compared two strategies for risk stratification for female participants: conventional risk assessment (CRA), which only involves information from genetic testing and personalised risk assessment (PRA), using genetic and non-genetic risk modifiers. Three different versions of PRA were compared, which were combinations of polygenic risk score and questionnaire-based factors. A patient-level Markov model was designed to estimate the overall National Health Service cost and quality-adjusted life years (QALYs) after risk assessment. Results were given for 20 different groups of women based on their GPV status and family history. Results Across the 20 scenarios, the results showed that PRA was cost-effective compared with CRA using a £20 000 per QALY threshold in women with a GPV in PALB2 who have OC or BC+OC family history, and women with a GPV in ATM, CHEK2, RAD51C or RAD51D. For women with a GPV in BRCA1 or BRCA2, women with no pathogenic variant and women with a GPV in PALB2 who have unknown family history or BC family history, CRA was more cost-effective. PRA was cost-effective compared with CRA in specific situations predominantly associated with moderate-risk BC GPVs (RAD51C/RAD51D/CHEK2/ATM), while CRA was cost-effective compared with PRA predominantly with high-risk BC GPVs (BRCA1/BRCA2/PALB2). Conclusion PRA was cost-effective in specific situations compared with CRA in the UK for assessment of women with or without GPVs in BC and OC susceptibility genes.

Testicular Sertoli cell tumour and potentially testicular Leydig cell tumour are features of DICER1 syndrome

DICER1 syndrome is a rare paediatric autosomal dominant inherited disorder predisposing to various benign and malignant tumours. It is caused by a germline pathogenic variant in DICER1, and the second hit for tumour development is usually a missense hotspot pathogenic variant in the DICER1 ribonuclease IIIb domain. While DICER1 predisposing variants account for about 60% of ovarian Sertoli-Leydig cell tumours, no DICER1-related testicular stromal tumours have been described. Here we report the first two cases of testicular stromal tumours in children carrying a DICER1 germline pathogenic variant: a case of Sertoli cell tumour and a case of Leydig cell tumour diagnosed at 2 and 12 years of age, respectively. A somatic DICER1 hotspot pathogenic variant was detected in the Sertoli cell tumour. This report extends the spectrum of DICER1-related tumours to include testicular Sertoli cell tumour and potentially testicular Leydig cell tumour. Diagnosis of a testicular Sertoli cell tumour should prompt DICER1 genetic testing so that patients with a DICER1 germline pathogenic variant can benefit from established surveillance guidelines. DICER1 genetic evaluation may be considered for testicular Leydig cell tumour. Our findings suggest that miRNA dysregulation underlies the aetiology of some testicular stromal tumours.

Oncologist-led BRCA counselling improves access to cancer genetic testing in middle-income Asian country, with no significant impact on psychosocial outcomes

Background Identifying patients with BRCA mutations is clinically important to inform on the potential response to treatment and for risk management of patients and their relatives. However, traditional referral routes may not meet clinical needs, and therefore, mainstreaming cancer genetics has been shown to be effective in some high-income and high health-literacy settings. To date, no study has reported on the feasibility of mainstreaming in low-income and middle-income settings, where the service considerations and health literacy could detrimentally affect the feasibility of mainstreaming. Methods The Mainstreaming Genetic Counselling for Ovarian Cancer Patients (MaGiC) study is a prospective, two-arm observational study comparing oncologist-led and genetics-led counselling. This study included 790 multiethnic patients with ovarian cancer from 23 sites in Malaysia. We compared the impact of different method of delivery of genetic counselling on the uptake of genetic testing and assessed the feasibility, knowledge and satisfaction of patients with ovarian cancer. Results Oncologists were satisfied with the mainstreaming experience, with 95% indicating a desire to incorporate testing into their clinical practice. The uptake of genetic testing was similar in the mainstreaming and genetics arm (80% and 79%, respectively). Patient satisfaction was high, whereas decision conflict and psychological impact were low in both arms of the study. Notably, decisional conflict, although lower than threshold, was higher for the mainstreaming group compared with the genetics arm. Overall, 13.5% of patients had a pathogenic variant in BRCA1 or BRCA2, and there was no difference between psychosocial measures for carriers in both arms. Conclusion The MaGiC study demonstrates that mainstreaming cancer genetics is feasible in low-resource and middle-resource Asian setting and increased coverage for genetic testing.

UK consensus recommendations for clinical management of cancer risk for women with germline pathogenic variants in cancer predisposition genes: RAD51C, RAD51D, BRIP1 and PALB2

Germline pathogenic variants (GPVs) in the cancer predisposition genes BRCA1, BRCA2, MLH1, MSH2, MSH6, BRIP1, PALB2, RAD51D and RAD51C are identified in approximately 15% of patients with ovarian cancer (OC). While there are clear guidelines around clinical management of cancer risk in patients with GPV in BRCA1, BRCA2, MLH1, MSH2 and MSH6, there are few guidelines on how to manage the more moderate OC risk in patients with GPV in BRIP1, PALB2, RAD51D and RAD51C, with clinical questions about appropriateness and timing of risk-reducing gynaecological surgery. Furthermore, while recognition of RAD51C and RAD51D as OC predisposition genes has been established for several years, an association with breast cancer (BC) has only more recently been described and clinical management of this risk has been unclear. With expansion of genetic testing of these genes to all patients with non-mucinous OC, new data on BC risk and improved estimates of OC risk, the UK Cancer Genetics Group and CanGene-CanVar project convened a 2-day meeting to reach a national consensus on clinical management of BRIP1, PALB2, RAD51D and RAD51C carriers in clinical practice. In this paper, we present a summary of the processes used to reach and agree on a consensus, as well as the key recommendations from the meeting.

APC germline pathogenic variants and epithelial ovarian cancer: causal or coincidental findings?

Abstract APC germline pathogenic variants result in predisposition to familial adenomatous polyposis and extraintestinal tumours such as desmoid fibromatosis, medulloblastomas and thyroid cancers. They have also been recently involved in ovarian microcystic stromal tumours. APC inactivation has been described at the tumour level in epithelial ovarian cancers (EOCs). Here, we report the identification of APC germline pathogenic variants in two patients diagnosed with premenopausal EOC in early 30s, with no other pathogenic variant detected in the known ovarian cancer predisposing genes. Subsequent tumour analysis showed neither a second hit of APC inactivation nor β-catenin activation. Both tumours did not have a homologous recombination (HR) deficiency, pointing towards the implication of other genes than those involved in HR. APC may contribute to the carcinogenesis of EOC in a multifactorial context. Further studies are required to clarify the role of APC in predisposition to EOC.

Enhancing the BOADICEA cancer risk prediction model to incorporate new data on RAD51C , RAD51D , BARD1 updates to tumour pathology and cancer incidence

Background BOADICEA (Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm) for breast cancer and the epithelial tubo-ovarian cancer (EOC) models included in the CanRisk tool ( www.canrisk.org ) provide future cancer risks based on pathogenic variants in cancer-susceptibility genes, polygenic risk scores, breast density, questionnaire-based risk factors and family history. Here, we extend the models to include the effects of pathogenic variants in recently established breast cancer and EOC susceptibility genes, up-to-date age-specific pathology distributions and continuous risk factors. Methods BOADICEA was extended to further incorporate the associations of pathogenic variants in BARD1 , RAD51C and RAD51D with breast cancer risk. The EOC model was extended to include the association of PALB2 pathogenic variants with EOC risk. Age-specific distributions of oestrogen-receptor-negative and triple-negative breast cancer status for pathogenic variant carriers in these genes and CHEK2 and ATM were also incorporated. A novel method to include continuous risk factors was developed, exemplified by including adult height as continuous. Results BARD1 , RAD51C and RAD51D explain 0.31% of the breast cancer polygenic variance. When incorporated into the multifactorial model, 34%–44% of these carriers would be reclassified to the near-population and 15%–22% to the high-risk categories based on the UK National Institute for Health and Care Excellence guidelines. Under the EOC multifactorial model, 62%, 35% and 3% of PALB2 carriers have lifetime EOC risks of <5%, 5%–10% and >10%, respectively. Including height as continuous, increased the breast cancer relative risk variance from 0.002 to 0.010. Conclusions These extensions will allow for better personalised risks for BARD1 , RAD51C , RAD51D and PALB2 pathogenic variant carriers and more informed choices on screening, prevention, risk factor modification or other risk-reducing options.

Contribution of large genomic rearrangements in PALB2 to familial breast cancer: implications for genetic testing

Background PALB2 is the most important contributor to familial breast cancer after BRCA1 and BRCA2. Large genomic rearrangements (LGRs) in BRCA1 and BRCA2 are routinely assessed in clinical testing and are a significant contributor to the yield of actionable findings. In contrast, the contribution of LGRs in PALB2 has not been systematically studied. Methods We performed targeted sequencing and real-time qPCR validation to identify LGRs in PALB2 in 5770 unrelated patients with familial breast cancer and 5741 cancer-free control women from the same Australian population. Results Seven large deletions ranging in size from 0.96 kbp to 18.07 kbp involving PALB2 were identified in seven cases, while no LGRs were identified in any of the controls. Six LGRs were considered pathogenic as they included one or more exons of PALB2 and disrupted the WD40 domain at the C terminal end of the PALB2 protein while one LGR only involved a partial region of intron 10 and was considered a variant of unknown significance. Altogether, pathogenic LGRs identified in this study accounted for 10.3% (6 of 58) of the pathogenic PALB2 variants detected among the 5770 families with familial breast cancer. Conclusions Our data show that a clinically important proportion of PALB2 pathogenic mutations in Australian patients with familial breast cancer are LGRs. Such observations have provided strong support for inclusion of PALB2 LGRs in routine clinical genetic testing.

Recurrent BRCA2 exon 3 deletion in Assyrian families

We identified six patients from five families with a recurrent mutation: NM_000059.3 (BRCA2) exon 3 deletion. All families self-identified as Assyrian. Assyrians are an ethnoreligious population of ancient Mesopotamia, now mostly living in modern day Iraq, Syria, Turkey and Iran. They are historically a socially isolated population with intermarriage within their community, living as a religious and language minority in mostly Muslim countries. The probands of each family presented with a classic BRCA2-associated cancer including early-onset breast cancer, epithelial serous ovarian cancer, male breast cancer and/or high-grade prostate cancer, and family history that was also significant for BRCA2-associated cancer. BRCA2 exon 3 deletion is classified as pathogenic and has been previously described in the literature, but it has not been described as a founder mutation in a particular population. We characterise this recurrent BRCA2 pathogenic variant in five Assyrian families in a single centre cohort.

Exploring the spectrum of central nervous system tumours in carriers of germline POT1 variants

Background Pathogenic variants in the protection of telomerase 1 ( POT1 ) gene are associated with predisposition to a broad spectrum of malignancies, although the specific genotype–phenotype correlation has not yet been fully elucidated. To further characterise the phenotypic spectrum, we describe six families with germline POT1 variants and evaluate existing literature to highlight the possible association between variants in POT1 , telomere dysregulation and predisposition to malignant central nervous system (CNS) tumours. Methods Genetic analyses were performed using an Illumina sequencing platform. All variants were examined by in silico analysis in Alamut as well as Rare Exome Variant Ensemble Learner (REVEL), and one variant was additionally examined by RNA analysis. Telomere length assessment was performed through RepeatDX Europe. Results We identified four missense and two frameshift POT1 germline variants: c.255G>C, p.(Lys85Asn), c.322G>A, p.(Gly108Arg), c.323G>A, p.(Gly108Glu), c.676C>T, p.(His226Tyr), c.707del, p.(Gly236Glufs*16) and c.709del, p.(Ser237Alafs*15). The variants c.255G>C and c.322G>A were observed in two patients with astrocytoma and c.676C>T in a patient with oligodendroglioma, corresponding to the most prevalent CNS tumour histopathology described in POT1 carriers in previous publications. Longer telomeres were found in probands with the CNS tumour phenotype. Conclusion Our findings support a possible association between pathogenic POT1 germline variants and increased risk of CNS tumours mainly oligodendroglioma, astrocytoma and glioblastoma. We highlight the potential importance of missense variants and telomeric measurement in tailoring of surveillance and advocate further studies to guide future personalised surveillance strategies.

Exploration of possible association of BRIP1 pathogenic variants with central nervous system cancers in an institutional cohort

BRIP1 (OMIM: 605882), associated with hereditary ovarian cancer, has recently been described in association with central nervous system (CNS) tumours. Institutional germline database review identified 43 families with BRIP1 pathogenic germline variants (PGVs); 7 families (16.3%) reported 8 CNS tumours. Somatic database review identified 1143 individuals with CNS tumours who underwent somatic sequencing, of whom 7 had BRIP1 pathogenic variants (PVs) (0.6%); 1 of 2 germline-tested individuals had a BRIP1 PGV. Though BRIP1 PVs are rare in CNS tumours, a substantial proportion of BRIP1 carriers have a positive family history. Obtaining and documenting the clinical and pathological characteristics of reported CNS tumours in BRIP1 individuals and families is key to exploring a possible association.

Effects of higher-than-expected control population allele frequency on classification of loss-of-function variants in cancer susceptibility genes

A query was sent to the cancer predisposition gene variant database Cancer Variant Interpretation Group UK, on the nonsense variant in NM_032043.3(BRIP1):c.2392C>T,p.(Arg798Ter). The submitter classified this as a variant of uncertain significance, providing very strong variant effect evidence with the intention of adding supporting pedigree information, according to the guidelines used for classification. However, the relatively high population frequency in the UKB cohort of 367/439 920 (0.083%) was a concern as it is higher than expected for the disease frequency, which would reduce the predicted pathogenicity score. This situation highlights the increasing concerns over the use of population data in pathogenicity classification of truncating/loss-of-function (LoF) variants in known cancer predisposition genes, particularly since the addition of UKB control data. Here, we have conducted a series of case-control comparisons for common truncating variants in known breast/ovarian cancer-associated genes, as well as LZTR1-related schwannomatosis, to address this issue using our Manchester cancer screening population compared with controls in UKB data. Our data show strong ORs for these common truncating variants. We propose that for truncating variants in cancer susceptibility genes with a significant case-control OR, apparently conflicting population frequency evidence criteria should be avoided.

Recontact to return new or updated PALB2 genetic results in the clinical laboratory setting

Objective The purpose of this study was to recontact individuals with clinically actionable test results identified through a retrospective research study and to provide a framework for laboratories to recontact patients. Methods Genetic testing was conducted on 2977 individuals originally referred for BRCA1 and BRCA2 hereditary breast and ovarian cancer testing that had a negative genetic test result. A gene panel was used to identify pathogenic variants in known or newly discovered genes that could explain the underlying cause of disease; however, analysis was restricted to PALB2 for the purposes of this study. A patient recontact decision tree was developed to assist in the returning of updated genetic test results to clinics and patients. Results Novel clinically actionable pathogenic variants were identified in the PALB2 gene in 18 participants (0.6%), the majority of whom were recontacted with their new or updated genetic test results. Eight individuals were unable to be recontacted; five individuals had already learnt about their new or updated findings from genetic testing outside the context of this study; three individuals prompted cascade testing in family members; two individuals were deceased. Conclusion Novel pathogenic variants in PALB2 were identified in 18 individuals through retrospective gene panel testing. Recontacting these individuals regarding these new or updated findings had a range of outcomes. The process of conveying genomic results within this framework can be effectively accomplished while upholding patient autonomy, potentially leading to advantageous outcomes for patients and their families.

Mosaic BRCA1 promoter methylation contribution in hereditary breast/ovarian cancer pedigrees

Purpose Mosaic BRCA1 promoter methylation (BRCA1meth) increases the risk of early-onset breast cancer, triple-negative breast cancer and ovarian cancer. As mosaic BRCA1meth are believed to occur de novo, their role in family breast/ovarian cancer has not been assessed. Patients Blood-derived DNA from 20 unrelated affected cases from families with aggregation of breast/ovarian cancer, but with no germline pathogenic variants in BRCA1/2, PALB2 or RAD51C/D, were screened by methylation-sensitive high-resolution melting. CpG analysis was performed by pyrosequencing on blood and buccal swab. Two probands carried a pathogenic variant in a moderate-penetrance gene (ATM and BARD1), and 8 of 18 others (44%) carried BRCA1meth (vs none of the 20 age-matched controls). Involvement of BRCA1 in tumourigenesis in methylated probands was demonstrated in most tested cases by detection of a loss of heterozygosity and a homologous recombination deficiency signature. Among the eight methylated probands, two had relatives with breast cancer with detectable BRCA1meth in blood, including one with high methylation levels in two non-tumour tissues. Conclusions The high prevalence of mosaic BRCA1meth in patients with breast/ovarian cancer with affected relatives, as well as this first description of a family aggregation of mosaic BRCA1meth, shows how this de novo event can contribute to hereditary breast/ovarian cancer pedigrees.

Sensitivity and specificity of loss of heterozygosity analysis for the classification of rare germline variants in BRCA1/2: results of the observational AGO-TR1 study (NCT02222883)

Variant-specific loss of heterozygosity (LOH) analyses may be useful to classify BRCA1/2 germline variants of unknown significance (VUS). The sensitivity and specificity of this approach, however, remains unknown. We performed comparative next-generation sequencing analyses of the BRCA1/2 genes using blood-derived and tumour-derived DNA of 488 patients with ovarian cancer enrolled in the observational AGO-TR1 trial (NCT02222883). Overall, 94 pathogenic, 90 benign and 24 VUS were identified in the germline. A significantly increased variant fraction (VF) of a germline variant in the tumour indicates loss of the wild-type allele; a decreased VF indicates loss of the variant allele. We demonstrate that significantly increased VFs predict pathogenicity with high sensitivity (0.84, 95% CI 0.77 to 0.91), poor specificity (0.63, 95% CI 0.53 to 0.73) and poor positive predictive value (PPV; 0.71, 95% CI 0.62 to 0.79). Significantly decreased VFs predict benignity with low sensitivity (0.26, 95% CI 0.17 to 0.35), high specificity (1.0, 95% CI 0.96 to 1.00) and PPV (1.0, 95% CI 0.85 to 1.00). Variant classification based on significantly increased VFs results in an unacceptable proportion of false-positive results. A significantly decreased VF in the tumour may be exploited as a reliable predictor for benignity, with no false-negative result observed. When applying the latter approach, VUS identified in four patients can now be considered benign. Trial registration number NCT02222883.

Assessment of mismatch repair deficiency in ovarian cancer

Background Hereditary causes of ovarian cancer include Lynch syndrome, which is due to inherited pathogenic variants affecting one of the four mismatch repair genes involved in DNA repair. The aim of this study was to evaluate tumour mismatch repair deficiency and prevalence of Lynch syndrome in high-risk women referred to the Manchester Centre for Genomic Medicine with ovarian cancer over the past 20 years. Methods Women with ovarian cancer diagnosed before the age of 35 years and/or with a suggestive personal or family history of Lynch syndrome cancers underwent tumour testing with immunohistochemistry for mismatch repair deficiency and, where indicated, MLH1 promoter methylation testing followed by constitutional testing for Lynch syndrome. Results In total, 261 ovarian cancers were tested and 27 (10.3%; 95% CI 6.9% to 14.7%) showed mismatch repair deficiency by immunohistochemistry. Three of 7 with MLH1 loss showed MLH1 promoter hypermethylation, and 18 of the remaining 24 underwent constitutional testing for Lynch syndrome. A further 15 women with mismatch repair proficient tumours underwent constitutional testing because of a strong family history of Lynch syndrome cancers. Pathogenic variants were identified in 9/33 (27%) women who underwent constitutional testing, aged 33–59 years (median 48 years), including one whose tumour was mismatch repair proficient. Most Lynch syndrome tumours were of endometrioid histological subtype. Conclusions Tumour mismatch repair deficiency identified by immunohistochemistry is a useful prescreen for constitutional testing in women with ovarian cancer with personal or family histories suggestive of Lynch syndrome.

Population-based targeted sequencing of 54 candidate genes identifies PALB2 as a susceptibility gene for high-grade serous ovarian cancer

Purpose The known epithelial ovarian cancer (EOC) susceptibility genes account for less than 50% of the heritable risk of ovarian cancer suggesting that other susceptibility genes exist. The aim of this study was to evaluate the contribution to ovarian cancer susceptibility of rare deleterious germline variants in a set of candidate genes. Methods We sequenced the coding region of 54 candidate genes in 6385 invasive EOC cases and 6115 controls of broad European ancestry. Genes with an increased frequency of putative deleterious variants in cases versus controls were further examined in an independent set of 14 135 EOC cases and 28 655 controls from the Ovarian Cancer Association Consortium and the UK Biobank. For each gene, we estimated the EOC risks and evaluated associations between germline variant status and clinical characteristics. Results The ORs associated for high-grade serous ovarian cancer were 3.01 for PALB2 (95% CI 1.59 to 5.68; p=0.00068), 1.99 for POLK (95% CI 1.15 to 3.43; p=0.014) and 4.07 for SLX4 (95% CI 1.34 to 12.4; p=0.013). Deleterious mutations in FBXO10 were associated with a reduced risk of disease (OR 0.27, 95% CI 0.07 to 1.00, p=0.049). However, based on the Bayes false discovery probability, only the association for PALB2 in high-grade serous ovarian cancer is likely to represent a true positive. Conclusions We have found strong evidence that carriers of PALB2 deleterious mutations are at increased risk of high-grade serous ovarian cancer. Whether the magnitude of risk is sufficiently high to warrant the inclusion of PALB2 in cancer gene panels for ovarian cancer risk testing is unclear; much larger sample sizes will be needed to provide sufficiently precise estimates for clinical counselling.

The avoiding late diagnosis of ovarian cancer (ALDO) project; a pilot national surveillance programme for women with pathogenic germline variants inBRCA1andBRCA2

BackgroundOur study aimed to establish ‘real-world’ performance and cost-effectiveness of ovarian cancer (OC) surveillance in women with pathogenic germlineBRCA1/2variants who defer risk-reducing bilateral salpingo-oophorectomy (RRSO).MethodsOur study recruited 875 femaleBRCA1/2-heterozygotes at 13 UK centres and via an online media campaign, with 767 undergoing at least one 4-monthly surveillance test with the Risk of Ovarian Cancer Algorithm (ROCA) test. Surveillance performance was calculated with modelling of occult cancers detected at RRSO. The incremental cost-effectiveness ratio (ICER) was calculated using Markov population cohort simulation.ResultsOur study identified 8 OCs during 1277 women screen years: 2 occult OCs at RRSO (both stage 1a), and 6 screen-detected; 3 of 6 (50%) were ≤stage 3a and 5 of 6 (83%) were completely surgically cytoreduced. Modelled sensitivity, specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) for OC were 87.5% (95% CI, 47.3 to 99.7), 99.9% (99.9–100), 75% (34.9–96.8) and 99.9% (99.9–100), respectively. The predicted number of quality-adjusted life years (QALY) gained by surveillance was 0.179 with an ICER cost-saving of -£102,496/QALY.ConclusionOC surveillance for women deferring RRSO in a ‘real-world’ setting is feasible and demonstrates similar performance to research trials; it down-stages OC, leading to a high complete cytoreduction rate and is cost-saving in the UK National Health Service (NHS) setting. While RRSO remains recommended management, ROCA-based surveillance may be considered for femaleBRCA-heterozygotes who are deferring such surgery.

MSH2 is the very young onset ovarian cancer predisposition gene, not BRCA1

Comprehensive epithelial tubo-ovarian cancer risk prediction model incorporating genetic and epidemiological risk factors

Background Epithelial tubo-ovarian cancer (EOC) has high mortality partly due to late diagnosis. Prevention is available but may be associated with adverse effects. A multifactorial risk model based on known genetic and epidemiological risk factors (RFs) for EOC can help identify women at higher risk who could benefit from targeted screening and prevention. Methods We developed a multifactorial EOC risk model for women of European ancestry incorporating the effects of pathogenic variants (PVs) in BRCA1 , BRCA2 , RAD51C , RAD51D and BRIP1 , a Polygenic Risk Score (PRS) of arbitrary size, the effects of RFs and explicit family history (FH) using a synthetic model approach. The PRS, PV and RFs were assumed to act multiplicatively. Results Based on a currently available PRS for EOC that explains 5% of the EOC polygenic variance, the estimated lifetime risks under the multifactorial model in the general population vary from 0.5% to 4.6% for the first to 99th percentiles of the EOC risk distribution. The corresponding range for women with an affected first-degree relative is 1.9%–10.3%. Based on the combined risk distribution, 33% of RAD51D PV carriers are expected to have a lifetime EOC risk of less than 10%. RFs provided the widest distribution, followed by the PRS. In an independent partial model validation, absolute and relative 5-year risks were well calibrated in quintiles of predicted risk. Conclusion This multifactorial risk model can facilitate stratification, in particular among women with FH of cancer and/or moderate-risk and high-risk PVs. The model is available via the CanRisk Tool ( www.canrisk.org ).

Surgical decision making in premenopausal BRCA carriers considering risk-reducing early salpingectomy or salpingo-oophorectomy: a qualitative study

BackgroundAcceptance of the role of the fallopian tube in ‘ovarian’ carcinogenesis and the detrimental sequelae of surgical menopause in premenopausal women following risk-reducing salpingo-oophorectomy (RRSO) has resulted in risk-reducing early-salpingectomy with delayed oophorectomy (RRESDO) being proposed as an attractive alternative risk-reducing strategy in women who decline/delay oophorectomy. We present the results of a qualitative study evaluating the decision-making process among BRCA carriers considering prophylactic surgeries (RRSO/RRESDO) as part of the multicentre PROTECTOR trial (ISRCTN:25173360).MethodsIn-depth semistructured 1:1 interviews conducted using a predeveloped topic-guide (development informed by literature review and expert consultation) until informational saturation reached. Wording and sequencing of questions were left open with probes used to elicit additional information. All interviews were audio-recorded, transcribed verbatim, transcripts analysed using an inductive theoretical framework and data managed using NVIVO-v12.ResultsInformational saturation was reached following 24 interviews. Seven interconnected themes integral to surgical decision making were identified: fertility/menopause/cancer risk reduction/surgical choices/surgical complications/sequence of ovarian-and-breast prophylactic surgeries/support/satisfaction. Women for whom maximising ovarian cancer risk reduction was relatively more important than early menopause/quality-of-life preferred RRSO, whereas those more concerned about detrimental impact of menopause chose RRESDO. Women managed in specialist familial cancer clinic settings compared with non-specialist settings felt they received better quality care, improved hormone replacement therapy access and were more satisfied.ConclusionMultiple contextual factors (medical, physical, psychological, social) influence timing of risk-reducing surgeries. RRESDO offers women delaying/declining premenopausal oophorectomy, particularly those concerned about menopausal effects, a degree of ovarian cancer risk reduction while avoiding early menopause. Care of high-risk women should be centralised to centres with specialist familial gynaecological cancer risk management services to provide a better-quality, streamlined, holistic multidisciplinary approach.

Variants of uncertain clinical significance in hereditary breast and ovarian cancer genes: best practices in functional analysis for clinical annotation

Germline DNA tests to identify pathogenic variants in genes linked to hereditary breast and ovarian cancer susceptibility have become widely available. However, the clinical utility of genetic testing depends on reliable evidence-based classification of sequence variants. Determination of pathogenicity traditionally relies on painstaking pedigree-based segregation analyses. However, the rapid increase in usage of germline DNA tests has led to the discovery of a large number of variants of uncertain clinical significance (VUS). For most VUS there is insufficient information for segregation analysis and therefore assessment of functional consequences is increasingly being used to support clinical annotation. Functional assays need to be accurate, robust, and reproducible to be used for clinical purposes. Here we use the lessons learned from

Gene fusions in tumourigenesis with particular reference to ovarian cancer

Gene fusion, a genomic event that generates a novel gene from two independent genes, has long been known to be implicated in tumourigenesis and cancer progression. It has thus served as a diagnostic and prognostic biomarker in cancer, as well as an ideal therapeutic target in cancer therapy. Gene fusion can arise from chromosomal rearrangement and alternative splicing of transcripts, resulting in deregulation of proto-oncogenes or creation of an oncogenic novel gene. Largely facilitated by next generation sequencing technologies, a plethora of novel gene fusions have been identified in a variety of cancers, which leaves us the challenge of functionally characterising these candidate gene fusions. In this review, we summarise the molecular mechanisms, the oncogenic consequences and the therapeutic implications of verified gene fusions. We also discuss recent studies on gene fusions in both common and rare subtypes of ovarian tumours and how these findings can be translated to cancer therapies to benefit patients carrying these gene fusions.

Multiregion whole-genome sequencing depicts intratumour heterogeneity and punctuated evolution in ovarian clear cell carcinoma

BackgroundOvarian clear cell carcinoma (OCCC) arises from endometriosis and represents a difficult-to-treat gynaecological malignancy, in part, because its spatial intratumour heterogeneity and temporal evolutionary trajectories have not been explicitly defined.MethodsWe performed whole-genome sequencing on six pathologically confirmed patients with OCCC. An R package named KataegisPortal was developed to identify and annotate loci of localised hypermutations. Immunohistochemical staining was conducted on a tissue microarray containing 143 OCCC specimens.ResultsMultiregion analysis demonstrated considerable degrees of subclonal diversification, ascribable to dynamic mutagenic processes, as well as macroevolutionary events including the acquisition of aneuploidy and chromoplexy. KataegisPortal unveiled APOBEC-mediated kataegis in the early phases of OCCC pathogenesis. We further showed evidence that APOBEC3A and APOBEC3B were frequently expressed in OCCC and possibly regulated by the MAPK pathway. Notably, APOBEC3B-expressing OCCC displayed favourable prognosis and appreciable immunogenicity manifested by marked cytotoxic T-cell infiltration.ConclusionsThese results point to an appealing model of punctuated tumour evolution underlying OCCC neoplastic transformation and progression, which may pose formidable challenges of early detection and intervention, and indicate the intratumour heterogeneity of cancer-driving alterations, yielding important implications for molecular diagnosis and targeted treatment of this lethal disease.

Retesting of women who are negative for a BRCA1 and BRCA2 mutation using a 20-gene panel

Background The value of retesting women who previously tested negative for a pathogenic variant (mutation) in BRCA1 and BRCA2 using an expanded panel of breast and ovarian cancer genes is unclear. Methods We studied 110 BRCA1/2-negative women who were retested using a panel of 20 breast and/or ovarian cancer susceptibility genes at the Advanced Molecular Diagnostics Laboratory (AMDL) at Mount Sinai Hospital in Toronto between March 2017 and March 2019. All patients had previously tested negative for BRCA pathogenic variants at the AMDL between January 2012 and March 2018 and were subsequently referred for retesting by their physician. Results Overall, six pathogenic variants in genes other than BRCA1 and BRCA2 were found (prevalence 5.5%). There were two pathogenic variants found in RAD51C, and one found in each of BRIP1, PALB2, PMS2 and PTEN. The prevalence of pathogenic variants was 6.5% for women affected with cancer (6 of 93), including 4.9% for women with breast cancer (4 of 82) and 22.2% for women with ovarian cancer (2 of 9). None of the 17 unaffected women had a clinically significant or pathogenic variant. There were 44 women (40%) for whom the result of the panel test was inconclusive due to the detection of a variant of uncertain significance. Conclusions Our findings indicate that the retesting of BRCA1/2-negative individuals with an expanded panel of 20 breast and ovarian cancer genes can produce clinically relevant results, with a yield of 5.5% for pathogenic variants in genes other than BRCA1 and BRCA2.

Familial risk of epithelial ovarian cancer after accounting for gynaecological surgery: a population-based study

Background Uptake of risk-reducing surgery has increased among women at high risk of epithelial ovarian cancer. We sought to characterise familial risk of epithelial ovarian cancer histotypes in a population-based study after accounting for gynaecological surgeries, including bilateral oophorectomy. Methods We compared risk of epithelial ovarian cancer in relatives of 3536 epithelial ovarian cancer cases diagnosed in 1966–2016 and relatives of 35 326 matched controls. We used Cox competing risk models, incorporating bilateral oophorectomy as a competing risk, to estimate the relative risk of ovarian cancer in first-degree (FDR), second-degree (SDR) and third-degree (TDR) relatives from 1966 to 2016. We also estimated relative risks in time periods before (1966–1994, 1995–2004) and after (2005–2016) formal recommendations were made for prophylactic oophorectomy among women with pathogenic variants in BRCA1/2. Results The relative risks of epithelial ovarian cancer in FDRs, SDRs and TDRs of cases versus controls were 1.68 (95% CI 1.39 to 2.04), 1.51 (95% CI 1.30 to 1.75) and 1.34 (95% CI 1.20 to 1.48), respectively. Relative risks were greatest for high-grade serous, mucinous and ‘other epithelial’ histotypes. Relative risks were attenuated for case FDRs, but not for SDRs or TDRs, from 2005 onwards, consistent with the timing of recommendations for prophylactic surgery. Conclusion Familial risk of epithelial ovarian cancer extends to TDRs, especially for high-grade serous and mucinous histotypes. Distant relatives share genes but minimal environment, highlighting the importance of germline inherited genetics in ovarian cancer aetiology. Increased ovarian cancer risk in distant relatives has implications for counselling and recommendations for prophylactic surgeries that, from our data, appear only to reach FDRs.

Practice guidelines for BRCA1/2 tumour testing in ovarian cancer

The purpose of this document is to provide pre-analytical, analytical and post-analytical considerations and recommendations to Canadian clinical laboratories developing, validating and offering next-generation sequencing (NGS)-based BRCA1 and BRCA2 (BRCA1/2) tumour testing in ovarian cancers. This document was drafted by the members of the Canadian College of Medical Geneticists (CCMG) somatic BRCA Ad Hoc Working Group, and representatives from the Canadian Association of Pathologists. The document was circulated to the CCMG members for comment. Following incorporation of feedback, this document has been approved by the CCMG board of directors. The CCMG is a Canadian organisation responsible for certifying medical geneticists and clinical laboratory geneticists, and for establishing professional and ethical standards for clinical genetics services in Canada. The current CCMG Practice Guidelines were developed as a resource for clinical laboratories in Canada; however, they are not inclusive of all information laboratories should consider in the validation and use of NGS for BRCA1/2 tumour testing in ovarian cancers.