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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/)., Competing Interests: Competing interests: ACA and DFE are named creators of the BOADICEA model which has been licensed by Cambridge Enterprise (University of Cambridge). All the other authors declare no conflict of interest., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY. Published by BMJ.)

Breast cancer (BC) risk for BRCA1 and BRCA2 mutation carriers varies by genetic and familial factors. About 50 common variants have been shown to modify BC risk for mutation carriers. All but three, were identified in general population studies. Other mutation carrier-specific susceptibility variants may exist but studies of mutation carriers have so far been underpowered. We conduct a novel case-only genome-wide association study comparing genotype frequencies between 60,212 general population BC cases and 13,007 cases with BRCA1 or BRCA2 mutations. We identify robust novel associations for 2 variants with BC for BRCA1 and 3 for BRCA2 mutation carriers, P < 10 -8 , at 5 loci, which are not associated with risk in the general population. They include rs60882887 at 11p11.2 where MADD, SP11 and EIF1, genes previously implicated in BC biology, are predicted as potential targets. These findings will contribute towards customising BC polygenic risk scores for BRCA1 and BRCA2 mutation carriers.

Background: BRCA1/2 mutations confer high lifetime risk of breast cancer, although other factors may modify this risk. Whether height or body mass index (BMI) modifies breast cancer risk in BRCA1/2 mutation carriers remains unclear., Methods: We used Mendelian randomization approaches to evaluate the association of height and BMI on breast cancer risk, using data from the Consortium of Investigators of Modifiers of BRCA1/2 with 14 676 BRCA1 and 7912 BRCA2 mutation carriers, including 11 451 cases of breast cancer. We created a height genetic score using 586 height-associated variants and a BMI genetic score using 93 BMI-associated variants. We examined both observed and genetically determined height and BMI with breast cancer risk using weighted Cox models. All statistical tests were two-sided., Results: Observed height was positively associated with breast cancer risk (HR = 1.09 per 10 cm increase, 95% confidence interval [CI] = 1.0 to 1.17; P = 1.17). Height genetic score was positively associated with breast cancer, although this was not statistically significant (per 10 cm increase in genetically predicted height, HR = 1.04, 95% CI = 0.93 to 1.17; P = .47). Observed BMI was inversely associated with breast cancer risk (per 5 kg/m2 increase, HR = 0.94, 95% CI = 0.90 to 0.98; P = .007). BMI genetic score was also inversely associated with breast cancer risk (per 5 kg/m2 increase in genetically predicted BMI, HR = 0.87, 95% CI = 0.76 to 0.98; P = .02). BMI was primarily associated with premenopausal breast cancer., Conclusion: Height is associated with overall breast cancer and BMI is associated with premenopausal breast cancer in BRCA1/2 mutation carriers. Incorporating height and BMI, particularly genetic score, into risk assessment may improve cancer management., (© The Author(s) 2018. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

To establish whether existing mutation prediction models can identify which male breast cancer (MBC) patients should be offered BRCA1 and BRCA2 diagnostic DNA screening, we compared the performance of BOADICEA (Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm), BRCAPRO (BRCA probability) and the Myriad prevalence table ("Myriad"). These models were evaluated using the family data of 307 Dutch MBC probands tested for BRCA1/2, 58 (19%) of whom were carriers. We compared the numbers of observed vs predicted carriers and assessed the Area Under the Receiver Operating Characteristic (ROC) Curve (AUC) for each model. BOADICEA predicted the total number of BRCA1/2 mutation carriers quite accurately (observed/predicted ratio: 0.94). When a cut-off of 10% and 20% prior probability was used, BRCAPRO showed a non-significant better performance (observed/predicted ratio BOADICEA: 0.81, 95% confidence interval [CI]: [0.60-1.09] and 0.79, 95% CI: [0.57-1.09], vs., Brcapro: 1.02, 95% CI: [0.75-1.38] and 0.94, 95% CI: [0.68-1.31], respectively). Myriad underestimated the number of carriers in up to 69% of the cases. BRCAPRO showed a non-significant, higher AUC than BOADICEA (0.798 vs 0.776). Myriad showed a significantly lower AUC (0.671). BRCAPRO and BOADICEA can efficiently identify MBC patients as BRCA1/2 mutation carriers. Besides their general applicability, these tools will be of particular value in countries with limited healthcare resources., (© 2017 The Authors. Clinical Genetics published by John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: It is unknown whether a history of breast cancer (BC) affects the outcome of BRCA1/2-associated epithelial ovarian cancer (EOC). This was investigated in the current analysis., Methods: We included 386 BRCA1/2-associated EOC patients diagnosed between 1980 and 2015. Progression-free survival (PFS), progression-free interval (PFI), overall survival (OS) and ovarian cancer-specific survival (OCSS) were compared between EOC patients with and without previous BC., Results: BRCA-associated EOC patients with, vs without, a BC history had a significantly worse PFS and PFI (multivariate hazard ratio (HR mult ) 1.47; 95% confidence interval (CI) 1.03-2.08 and HR mult 1.43; 95% CI 1.01-2.03), and a non-significantly worse OS (HR mult 1.15; 95% CI 0.84-1.57) and OCSS (HR mult 1.18; 95% CI 0.85-1.62). Ovarian cancer-specific survival was significantly worse for the subgroup treated with adjuvant chemotherapy for BC (HR mult 1.99; 95% CI 1.21-3.31)., Conclusions: Our results suggest that BRCA1/2-associated EOC patients with a previous BC have a worse outcome than EOC patients without BC, especially when treated with adjuvant chemotherapy.

Background: Paternal transmission of a BRCA mutation has been reported to increase the risk of breast cancer in offspring more than when the mutation is maternally inherited. As this effect might be caused by referral bias, the aim of this study was to assess the parent-of-origin effect of the BRCA1/2 mutation on the breast cancer lifetime risk, when adjusted for referral bias., Methods: A Dutch national cohort including 1,314 proven BRCA1/2 mutation carriers and covering 54,752 person years. Data were collected by family cancer clinics, via questionnaires and from the national Dutch Cancer Registry. The parent-of-origin effect was assessed using Cox regression analyses, both unadjusted and adjusted for referral bias. Referral bias was operationalized by number of relatives with cancer and by personal cancer history., Results: The mutation was of paternal origin in 330 (42%, P < 0.001) BRCA1 and 222 (42%, P < 0.001) BRCA2 carriers. Paternal origin increased the risk of prevalent breast cancer for BRCA1 [HR, 1.54; 95% confidence interval (CI), 1.19-2.00] and BRCA2 carriers (HR, 1.40; 95% CI, 0.95-2.06). Adjusted for referral bias by several family history factors, these HRs ranged from 1.41 to 1.83 in BRCA1 carriers and 1.27 to 1.62 in BRCA2 carriers. Adjusted for referral bias by personal history, these HRs were 0.66 (95% CI, 0.25-1.71) and 1.14 (95% CI, 0.42-3.15), respectively., Conclusion: A parent-of-origin effect is present after correction for referral bias by family history, but correction for the personal cancer history made the effect disappear., Impact: There is no conclusive evidence regarding incorporating a BRCA1/2 parent-of-origin effect in breast cancer risk prediction models. Cancer Epidemiol Biomarkers Prev; 25(8); 1251-8. ©2016 AACR., (©2016 American Association for Cancer Research.)

Fanconi anemia (FA) is a rare recessive disorder with chromosomal instability, congenital abnormalities, and a high cancer risk. The breast cancer susceptibility gene BRCA2 (FANCD1) is one of the 16 genes involved in this recessive disease. We have identified a novel mutation of the splice donor site of intron 1 in the noncoding region of BRCA2 in a Japanese FA family. This mutation may account for the FA phenotype in a patient originally reported to have biallelic mutations in BRCA2. Subsequent functional studies revealed that one of the mutations, K2729N, was a neutral change. As reported here, a more careful analysis resulted in the identification of a novel splice site mutation. Functional analysis using a mouse embryonic stem cell-based assay revealed that it causes aberrant splicing, reduced transcript levels and hypersensitivity to DNA damaging agents, suggesting that it is likely to be pathogenic. Although similar pathogenic variants in the noncoding region of BRCA1 and 2 were not identified in a cohort of 752 familial breast cancer cases, we still think this finding is relevant for mutation analysis in Hereditary Breast and Ovarian Cancer Syndrome families in a diagnostic setting., (© 2014 WILEY PERIODICALS, INC.)

Background: Recent studies suggested an improved overall survival (OS) for BRCA2- versus BRCA1-associated epithelial ovarian cancer (EOC), whereas the impact of chemotherapy is not yet clear. In a nationwide cohort, we examined the results of primary treatment, progression-free survival (PFS), treatment-free interval (TFI), and OS of BRCA1 versus BRCA2 EOC patients., Methods: Two hundred and forty-five BRCA1- and 99 BRCA2-associated EOC patients were identified through all Dutch university hospitals. Analyses were carried out with the Pearson's Chi-square test, Kaplan-Meier, and Cox regression methods., Results: BRCA1 patients were younger at EOC diagnosis than BRCA2 patients (51 versus 55 years; P < 0.001), without differences regarding histology, tumor grade, and International Federation of Gynecology and Obstetrics (FIGO) stage. Complete response rates after primary treatment, including chemotherapy, did not differ between BRCA1 (86%) and BRCA2 patients (90%). BRCA1 versus BRCA2 patients had a shorter PFS (median 2.2 versus 3.9 years, respectively; P = 0.006), TFI (median 1.7 versus 2.8 years; P = 0.009), and OS (median 6.0 versus 9.7 years; P = 0.04). Differences could not be explained by age at diagnosis, FIGO stage or type of treatment., Conclusions: PFS and OS were substantially longer in BRCA2- than in BRCA1-associated EOC patients. While response rates after primary treatment were similarly high in both groups, TFI, as surrogate for chemosensitivity, was significantly longer in BRCA2 patients.

BRCA2 and PALB2 function together in the Fanconi anemia (FA)-Breast Cancer (BRCA) pathway. Mono-allelic and bi-allelic BRCA2 and PALB2 mutation carriers share many clinical characteristics. Mono-allelic germline mutations of BRCA2 and PALB2 are risk alleles of female breast cancer and have also been reported in familial pancreatic cancer, and bi-allelic mutations cause a severe form of Fanconi anemia. In view of these similarities, we investigated whether the prevalence of PALB2 mutations was increased in breast cancer families with the occurrence of BRCA2 associated tumours other than female breast cancer. PALB2 mutation analysis was performed in 110 non-BRCA1/2 cancer patients: (a) 53 ovarian cancer patients from female breast-and/or ovarian cancer families; (b) 45 breast cancer patients with a first or second degree relative with pancreatic cancer; and (c) 12 male breast cancer patients from female breast cancer families. One truncating PALB2 mutation, c.509&#95;510delGA, resulting in p.Arg170X, was found in a male breast cancer patient. We conclude that germline mutations of PALB2 do not significantly contribute to cancer risk in non-BRCA1/2 cancer families with at least one patient with ovarian cancer, male breast cancer, and/or pancreatic cancer.