BRCA1 and BRCA2 germline testing in Cretan isolates reveals novel and strong founder effects

Germline BRCA1 and BRCA2 loss-of-function variants have been linked to increased breast and ovarian cancer risk, with more than 5,000 distinct pathogenic variants being reported worldwide. Among individuals of Greek descent, the BRCA1/2 variant spectrum is heterogeneous, but characterized by strong founder effects. As patients from certain geographical regions of Greece (like Crete) were underrepresented in previous studies, we hypothesized that isolated Cretans, a southern Greece islanders' population with distinct demographic, cultural and genetic features, could harbor founder BRCA1/2 mutations. A total of 304 breast or/and ovarian cancer patients of Cretan descent, fulfilling NCCN criteria for genetic testing, were tested by NGS or Sanger sequencing, followed by MLPA. Haplotype analysis was subsequently performed to investigate potential founder effects of recurrent alleles. Overall, 16.5% (50/304) of the tested patients carried 22 different pathogenic variants; 48% in BRCA1, 52% in BRCA2. Three variants, namely two in BRCA2 (Δexons 12 and 13 and c.7806-2A>T) and one in BRCA1 (c.5492del), constituting approximately half (48%) of all detected pathogenic variants, were shown to have a founder effect, with all carriers sharing common haplotypes. Remarkably, these variants were confined to Cretans and have not been identified in other regions of Greece. The high prevalence of specific BRCA1/2 pathogenic variants among Cretans, provides the possibility of cost- and time-efficient screening of the Cretan population. Integrating this knowledge in local public health services may have a significant impact on cancer prevention, and may serve as a starting point for the implementation of testing on a population level.     

Recurrent BRCA1 Mutation,but no BRCA2 Mutation,in Vietnamese Patients with Ovarian Carcinoma Detected with Next Generation Sequencing

Background: Identification of germline and somatic BRCA1/2 mutations in ovarian cancer is important for genetic counseling and treatment decision making with poly ADP ribose polymerase inhibitors. Unfortunately, data on the frequency of BRCA1/2 mutations in Vietnamese patients are scare. Methods: We aim to explore the occurrence of BRCA1/2 mutations in 101 Vietnamese patients with ovarian cancer including serous (n = 58), endometrioid (n = 14), mucinous (n = 24), and clear cell (n = 5) carcinomas. BRCA1/2 mutations were detected from formalin-fixed parafin-embedded tumor samples using the OncomineTM BRCA Research Assay on Personal Genome Machine Platform with Ion Reporter Software for sequencing data analysis. The presence of pathogenic mutations was confirmed by Sanger sequencing. Results: We found no BRCA2 mutation in the entire cohort. Four types of pathogenic mutations in BRCA1 (Ser454Ter, Gln541Ter, Arg1751Ter, and Gln1779AsnfsTer14) were detected in 8 unrelated patients (7.9%) belonging to serous and endometrioid carcinoma groups. Except for the c.1360_1361delAG (Ser454Ter) mutation in BRCA1 exon 11 that was somatic, the other mutations in exons 11, 20, and 22 were germline.  Interestingly, the recurrent Arg1751Ter mutation in BRCA1 exon 20 appeared in 4 patients, suggesting that this is a founder mutation in Vietnamese patients. Conclusion: Mutational analysis of tumor tissue using next generation sequencing allowed the detection of both germline and somatic BRCA1/2 mutations.     

BRCA1 and BRCA2 Common Mutations in Iranian Breast Cancer Patients: a Meta Analysis

Background: To date several common mutations in BRCA1 and BRCA2 associated with breast cancer havebeen reported in different populations. However, the common BRCA1 and BRCA2 mutations among breastcancer patients in Iran have not been described in detail. Materials and Methods: To comprehensively assessthe frequency and distribution of the most common BRCA1 and BRCA2 mutations in Iranian breast cancerpatients, we conducted this meta-analysis on 13 relevant published studies indentified in a literature searchon PubMed and SID. Results: A total of 11 BRCA1 and BRCA2 distinct common mutations were identified,reported twice or more in the articles, of which 10 (c.2311T>C, c.3113A>G, c.4308T>C, c.4837A>G, c.2612C>T,c.3119G>A, c.3548A>G, c.5213G>A c.IVS16-92A/G, and c.IVS16-68A/G) mutations were in BRCA1, and 1(c.4770A>G) was in BRCA2. The mutations were in exon 11, exon 13, intron 16, and exon 20 of BRCA1 andexon 11 of BRCA2. All have been previously reported in different populations. Conclusions: These meta analysisresults should be helpful in understanding the possibility of any first true founder mutation of BRCA1/BRCA2in the Iranian population. In addition, they will be of significance for diagnostic testing, genetic counseling andfor epidemiological studies.     

The Contribution of BRCA1 and BRCA2 to Ovarian Cancer

Germline mutations of the BRCA1 and BRCA2 genes confer a high life‐time risk of ovarian cancer. They represent the most significant and well characterised genetic risk factors so far identified for the disease. The frequency with which BRCA1/2 mutations occur in families containing multiple cases of ovarian cancer or breast and ovarian cancer, and in population‐based ovarian cancer series varies geographically and between different ethnic groups. There are differences in the frequency of common mutations and in the presence of specific founder mutations in different populations. BRCA1 and BRCA2 are responsible for half of all families containing two or more ovarian cancer cases. In population‐based studies, BRCA1 and BRCA2 mutations are present in 5–15% of all ovarian cancer cases. Often, individuals in which mutations are identified in unselected cases have no family history of either ovarian or breast cancer. The ability to identify BRCA1/2 mutations has been one of the few major success stories over the last few years in the clinical management of ovarian cancer. Currently, unaffected individuals can be screened for mutations if they have a family history of the disease. If a mutation is identified in the family, and if an individual is found be a mutation carrier, they can be offered clinical intervention strategies that can dramatically reduce their ovarian cancer risks. In some populations with frequent founder mutations screening may not be dependant on whether a mutation is identified in an affected relative.     

Cancer risks among BRCA1 and BRCA2 mutation carriers

BRCA1 and BRCA2 mutations increase breast and ovarian cancer risks substantially enough to warrant risk reduction surgery, despite variable risk estimates. Underlying this variability are methodological issues, and also complex genetic and nongenetic effects. Although many modifying factors are unidentified, known factors can already be incorporated in individualised risk prediction.     

Prevalence and clinical characterization of BRCA1 and BRCA2 mutations in Korean patients with epithelial ovarian cancer

This study was performed to investigate the prevalence, clinical characteristics, and treatment response according to BRCA1 and BRCA2 (BRCA) mutations in Korean patients with epithelial ovarian cancer (EOC). Two-hundred and ninety-eight Korean women diagnosed with high-grade serous and/or endometrioid EOC from 2010 to 2015 were tested for germline and 86 specimens for somatic BRCA mutations, regardless of the family history. Clinical characteristics including survival outcomes were compared in patients with and without BRCA mutations (NCT02963688). A total of 43 different germline BRCA mutations were identified in 78 patients among 298 patients (26.2%). Somatic BRCA mutations were identified in 11 (12.8%) patients among patients without germline BRCA mutations. Haplotype analysis demonstrated no founder mutations in our Korean patient cohort. Insignificant differences in age at diagnosis, primary site, and residual disease after surgery were observed between patients with and without BRCA mutations. In multivariate analysis for overall survival (OS), the presence of BRCA mutation was significantly associated with OS (P = .049) in addition to platinum sensitivity (P < .001), indicating it is an independent prognostic factor for survival regardless of platinum sensitivity to first-line chemotherapy. In addition, a higher response rate to subsequent chemotherapy after recurrence was observed in EOC patients with BRCA mutations resulting in better OS. In the current study, the prevalence of BRCA mutations in Korean patients with EOC was higher than previously reported in other ethnic groups. We demonstrated characteristics and treatment response in Korean EOC patients with BRCA mutations. These findings may provide valuable information to be considered in future clinical trials including Asian patients.     

Challenges and Considerations on Risk-Reducing Surgery in BRCA1/2 Patients with Advanced Breast Cancer

Cancer survivors harboring inherited pathogenic variants in the breast cancer (BC) susceptibility genes BRCA1 or BRCA2 are at increased risk of ovarian cancer (OC) and also of contralateral BC. For these women, risk-reducing surgery (RRS) may contribute to risk management. However, women with locally advanced or metastatic breast cancer (ABC) were excluded from clinical trials evaluating the benefit of these procedures in the BRCA1/2 carriers, and thus, current guidelines do not recommend RRS in this specific setting. Although ABC remains an incurable disease, recent advances in treatment have led to increased survival, which, together with improvement in RRS techniques, raise questions about the potential role of RRS in the management of BRCA1/2 ABC patients. When should RRS be discussed as an option for BRCA1/2 patients diagnosed with ABC? To address this issue, we report two clinical cases that reflect new challenges in routine oncology practice. Team experience and patient motivations may shape multidisciplinary decisions in the absence of evidence-based data. A wise rationale may be the analysis of the competing risks of death by a previous ABC against risk of death by a secondary BC or OC, tailored to patient preferences.     

BRCA1 and BRCA2 mutations in Turkish breast/ovarian families and young breast cancer patients

To date, BRCA1 and BRCA2 mutations in breast and/or ovarian patients have not been characterized in the Turkish population. We investigated the presence of BRCA mutations in 53 individuals with a personal and family history of breast and/or ovarian cancer, and 52 individuals with a personal history of breast cancer diagnosed below age 50 without additional family history. We have identified 11 mutations (nine BRCA1 and two BRCA2) using combined techniques involving protein truncation test, direct sequencing and heteroduplex analysis. We found eight out of 53 patients (15.1%) with a family history to carry BRCA gene mutations (seven BRCA1 and one BRCA2). Of these, four were found in 43 families presenting only breast cancer histories, and four were found in families presenting ovarian cancer with or without breast cancer. We also demonstrated two BRCA1 and one BRCA2 mutations in three out of 52 (5.8%) early-onset breast cancer cases without additional family history. Three of nine BRCA1 and both BRCA2 mutations detected in this study were not reported previously. These mutations may be specific to the Turkish population. The BRCA1 5382insC mutation, specific to Ashkenazi and Russian populations, was found twice in our study group, representing a possible founder mutation in the Turkish population.     

Prevalence of BRCA1 and BRCA2 Germline Mutations in Patients of African Descent with Early-Onset and Familial Colombian Breast Cancer

BackgroundPathogenic germline mutations in the BRCA1 and BRCA2 (BRCA1/2) genes contribute to hereditary breast/ovarian cancer (OC) in White/mestizo Colombian women. As there is virtually no genetic data on breast cancer (BC) in Colombians of African descent, we conducted a comprehensive BRCA1/2 mutational analysis of 60 Afro-Colombian families affected by breast/OC.Materials and MethodsMutation screening of the complete BRCA1/2 genes for small-scale mutations and large genomic alterations was performed in these families using next-generation sequencing and multiplex ligation-dependent probe amplification analysis.ResultsFour pathogenic germline mutations, including one novel mutation, were identified, comprising 3 in BRCA1 and one in BRCA2. The prevalence of BRCA1/2 mutations, including one BRCA1 founder mutation (c.5123C>A) previously identified in this sample set, was 3.9% (2/51) in female BC-affected families and 33.3% (3/9) in those affected by both breast and OC. Haplotype analysis of 2 BRCA2_c.2701delC carriers (one Afro-Colombian and one previously identified White/mestizo Colombian patient with BC) suggested that the mutation arose in a common ancestor.ConclusionOur data showed that 2/5 (40%) mutations (including the one previously identified in this sample set) are shared by White/mestizo Colombian and Afro-Colombian populations. This suggests that these 2 populations are closely related. Nevertheless, variations in the BRCA1/2 mutational spectrum among Afro-Colombian subgroups from different regions of the country were observed, suggesting that specific genetic risk assessment strategies need to be developed.     

Prevalence of BRCA1 and BRCA2 mutations in Pakistani breast and ovarian cancer patients

Among Asian countries, Pakistan has the highest rates of breast and ovarian cancer. To assess the contribution of the BRCA1 and BRCA2 germ line mutations to these high rates, we conducted the first study of 176 Pakistani breast and ovarian cancer patients, selected on family history and on age of diagnosis. Comprehensive BRCA mutation screening was performed using a range of techniques, including denaturing high-pressure liquid chromatography, single strand conformational polymorphism analysis and protein truncation test, followed by DNA sequencing. Thirty deleterious germ-line mutations were identified in the 176 families (17.0%), including 23 in BRCA1 and 7 in BRCA2. Four mutations, 185delAG, 185insA, S1503X and R1835X, were recurrent; these accounted for 52% of all identified BRCA1 mutations. Haplotype analyses suggested founder effects for 3 of these. The prevalence of BRCA1 or BRCA2 mutations was 42.8% for families with multiple cases of breast cancer, and was 50.0% for the breast/ovarian cancer families. The prevalence of mutations was 11.9% for single cases of early-onset breast cancer (< or =30 years) and was 9.0% for single cases of early-onset ovarian cancer (< or =45 years). Our findings show that BRCA mutations account for a substantial proportion of hereditary breast/ovarian cancer and early-onset breast and ovarian cancer cases in Pakistan.     

No Association between BRCA1 Immunohistochemical Expression and Tumor Grade,Stage or Overall Survival in Platinum-Treated Epithelial Ovarian Cancer Patients

Background: The aim of this work is to assess the frequency of BRCA1 protein immunohistochemical (IHC)expression in epithelial ovarian cancer (EOC) and to evaluate the association of BRCA1 expression with clinicaland pathological characteristics and the overall survival (OS) of patients treated with postoperative platinumbasedchemotherapeutic agents. Materials and Methods: This retrospective study was conducted on 35 cases ofepithelial ovarian cancer selected from the files of the Pathology Department, Faculty of Medicine, MansouraUniversity, Egypt. Immunohistochemistry (IHC) was performed for BRCA1 gene protein. BRCA1 expressionwas compared to patient’s age, tumor histology, grade, stage and OS time. Statistical analysis was carried outwith the SPSS version 16.0 to assess significant associations. Results: BRCA1 nuclear expression was detectedin 40% of EOC, in which a mild increase in the percentage of positive cases was observed with serous histology,stage IV, and grade 3 carcinomas. There was a significant statistical difference in BRCA1 expression with regardto histological subtypes of EOC (p=0.048), but not grade or stage. Mean OS and survival rate were slightly betterfor BRCA1 expressing group, but there was no statistically significant difference (p=0.528). Conclusions: Noassociation between BRCA1 immunohistochemical expression and tumor grade, stage or overall survival wasnoted in platinum-treated epithelial ovarian cancer patients.     

Somatic mutations in the BRCA2 gene and high frequency of allelic loss of BRCA2 in sporadic male breast cancer

Breast cancer occurs rarely in men and risk factors for the disease include germline mutations of the BRCA2 gene. High frequency of allelic loss at the BRCA2 locus has been reported in sporadic breast tumors, but somatic mutations of BRCA2 are very rare. Here we report the first case of somatic BRCA2 mutation in male breast cancer with demonstrated loss of heterozygosity. We analyzed a series of 27 archival samples from male breast cancer patients for BRCA2 mutations and loss of heterozygosity at BRCA2 locus. The mutation analysis of BRCA2 gene was performed using SSCA-HA and sequencing methods. PCR was used to detect LOH at 3 highly polymorphic microsatellite markers spanning BRCA2 region on 13q by comparing the allelic pattern in matched tumor and blood DNA samples. In this study LOH at the BRCA2 locus was observed in 82.6% of informative cases, confirming previous observations on high frequency of LOH affecting the BRCA2 region in male breast cancer. We identified 5 somatic BRCA2 mutations in a set of 23 sporadic male breast cancers (21%). Two silent and 1 missense alterations were novel BRCA2 variants. Here we also report first somatic frameshift BRCA2 mutation in male breast cancer 8138del5. In 3 tumors with somatic BRCA2 alterations, 1 missense, 1 silent and frameshift LOH at chromosome 13q12-13 were detected and losses involved a wild-type allele of BRCA2 gene.     

BRCA1 and BRCA2 Mutations in Breast and Ovarian Cancer Syndrome: Reflection on the Creighton University Historical Series of High Risk Families

Over the last four decades, Henry Lynch has collected pedigrees and samples from high risk breast and/or ovarian cancer families, generating a unique resource for the study of breast cancer susceptibility. These families have made a major contribution to increasing our knowledge in the cancer genetic susceptibility field, allowing the discovery of a genetic association between breast and ovarian cancer predisposition, contributing to the mapping of the BRCA1 and BRCA2 genes, advancing the idea of the existence of other breast cancer susceptibility genes, allowing the evaluation of BRCA-associated cancer risks and psychosocial aspects of BRCA testing and so on. Ten years after the cloning of BRCA1 and BRCA2, we report the current status of these families and compare the observed BRCA1/2 mutation detection rate with the estimations obtained by linkage analysis of the Breast Cancer Linkage Consortium families.     

Survival outcomes of metastatic breast cancer patients by germline BRCA1/2 status in a large multicenter real-world database

The outcomes and best treatment strategies for germline BRCA1/2 mutation (gBRCAm) carriers with metastatic breast cancer (MBC) remain uncertain. We compared the overall survival and the first line progression free survival (PFS1) of patients with a gBRCAm identified at initiation of first-line treatment with those of BRCA wild-type (WT) and not-tested (NT) individuals in the ESME real-world database of MBC patients between 2008 and 2016 (NCT03275311). Among the 20 624 eligible patients, 325 had a gBRCAm, 1138 were WT and 19 161 NT. Compared with WT, gBRCAm carriers were younger, and had more aggressive diseases. At a median follow-up of 50.5 months, median OS was 30.6 (95%CI: 21.9-34.3), 35.8 (95%CI: 32.2-37.8) and 39.3 months (95% CI: 38.3-40.3) in the gBRCAm, WT and NT subgroups, respectively. Median PFS1 was 7.9 (95%CI: 6.6-9.3), 7.8 (95%CI: 7.3-8.5) and 9.7 months (95%CI, 9.5-10.0). In the multivariable analysis conducted in the whole cohort, gBRCAm status had however no independent prognostic impact on OS and PFS1. Though, in the triple-negative subgroup, gBRCAm patients had better OS and PFS1 (HR vs WT = 0.76; 95%CI: 0.60-0.97; P = .027 and 0.69; 95% CI: 0.55-0.86; P = .001, respectively). In contrast, in patients with HR+/HER2 negative cancers, PFS1 appeared significantly and OS non significantly lower for gBRCAm carriers (PFS1: HR vs WT = 1.23; 95%CI: 1.03-1.46; P = .024; OS:HR = 1.22, 95% CI: 0.97-1.52, P = .089). In conclusion, gBRCA1/2 status appears to have divergent survival effects in MBC according to IHC subtype.     

Japanese nationwide observational multicenter study of tumor BRCA1/2 variant testing in advanced ovarian cancer

The association between germline BRCA1 and BRCA2 pathogenic variants (mutations: gBRCAm) and ovarian cancer risk is well established. Germline testing alone cannot detect somatic BRCA1/2 pathogenic variants (sBRCAm), which is calculated based on the proportion of tumor BRCAm (tBRCAm) from tumor samples and gBRCAm. Homologous recombination deficiency (HRD) results mainly from genetic/epigenetic alterations in homologous recombination repair-related genes and can be evaluated by genomic instability status. In Japan, the prevalence of tBRCAm, sBRCAm, and HRD remains unclear. This multicenter, cross-sectional, observational study, CHaRacterIzing the croSs-secTional approach to invEstigate the prevaLence of tissue BRCA1/2 mutations in newLy diagnosEd advanced ovarian cancer patients (CHRISTELLE), evaluated the prevalence of tBRCAm, sBRCAm, and HRD in tumor specimens from newly diagnosed patients with ovarian cancer who underwent gBRCA testing. Of the 205 patients analyzed, 26.8% had a tBRCAm, including tBRCA1m (17.6%) and tBRCA2m (9.3%). The overall prevalence of tBRCAm, gBRCAm, sBRCAm, and HRD-positive status was 26.8%, 21.5%, 6.3%, and 60.0%, respectively. The calculated sBRCAm/tBRCAm ratio was 23.6% (13/55), and the prevalence of gBRCA variant of uncertain significance was 3.9%. These results suggest gBRCA testing alone cannot clearly identify the best course of treatment, highlighting the importance of sBRCA testing in Japan. The present results also suggest that testing for tBRCA and HRD should be encouraged in advanced ovarian cancer patients to drive precision medicine.     

BRCA1 and BRCA2: Chemosensitivity, Treatment Outcomes and Prognosis

BRCA1 and BRCA2 are important breast and ovarian cancer susceptibility genes, and mutations in these two genes confer lifetime risks of breast cancer of up to 80% and ovarian cancer risks of up to 40%. Clinico-pathological studies have identified features that are specific to BRCA1-related breast cancer, but this has been more difficult for BRCA2-related breast cancer. Ovarian cancers due to BRCA1 or BRCA2 mutations cannot usually be distinguished from their non-hereditary counterparts on morphological grounds, but micro-array data suggest that differences do exist. Prognostic studies have shown that breast cancer in a BRCA1 mutation carrier is likely to have a similar, or worse, outcome than that occurring in a BRCA2- or non-carrier of the same age. By contrast, most studies indicate that women developing a BRCA1/2-related ovarian cancer have an improved survival compared with non-carriers, particularly if they receive platinum-based therapy. In support of this, in vitro chemo-sensitivity studies have found that human cells lacking BRCA1 may be particularly sensitive to cisplatinum and to other drugs that cause double-strand breaks in DNA. Nevertheless, in breast cancer, little is known regarding clinically important differences in response to chemotherapy between BRCA1/2 mutation carriers and non-carriers, and between different chemotherapeutic regimens within existing series of BRCA1/2 mutation carriers. There are no published prospective studies. It is hoped that, in the near future, randomised controlled trials will be started with the aim of answering these important clinical questions.