BRCA1 and BRCA2 mutation status and cancer family history of Danish women affected with multifocal or bilateral breast cancer at a young age

Tumor Characteristics of Bilateral Breast Cancer Compared with Unilateral Breast Cancer

BACKGROUND

Bilateral breast cancer (BC) has an incidence of 1 to 3 %. This study aimed to describe the clinicopathologic characteristics and management of bilateral BC, estimate disease-free survival (DFS), and compare DFS with unilateral BC.

METHODS

A retrospective analysis was performed for patients who had bilateral invasive BC or unilateral invasive BC and contralateral ductal carcinoma in situ (DCIS) treated at Mayo Clinic Rochester from 2008 to 2022. A 4:1 matched cohort of patients with unilateral invasive BC was used for comparison. The groups were compared using Wilcoxon rank-sum or chi-square tests. Disease-free survival was analyzed using the Kaplan-Meier method and log-rank test, with Cox proportional hazards regression used for multivariable analysis.

RESULTS

The study identified 278 cases of bilateral breast cancer (177 cases of bilateral invasive cancer and 101 cases of unilateral invasive cancer with contralateral DCIS), representing 4.1 % of invasive BCs. Biologic subtype was concordant between sides in 79.8 % of the patients. Initial surgery was bilateral mastectomy for 76.6 %, bilateral lumpectomy for 20.5 %, and unilateral mastectomy with unilateral lumpectomy for 2.9 % of the patients. Pathogenic variants in breast cancer predisposition genes were present in 21.7 % of those tested. The patients who had bilateral BC presented with a higher cT category than the patients who had unilateral BC (p = 0.02), and a higher proportion presented with ILC (17.3 % vs 10.9 %; p = 0.004), estrogen receptor-positive (ER+) disease (89.2 % vs 84.2 %; p = 0.04), multicentric/multifocal disease (37.1 % vs 24.3 %; p < 0.001), breast cancer pathogenic variant (21.7 % vs 12.4 %; p = 0.02), and palpable presentation (48.2 % vs 40.8 %; p = 0.03). The patients with bilateral BC showed DFS similar to that for the unilateral BC cohort (p = 0.71).

CONCLUSIONS

Bilateral BCs most commonly are biologically concordant between sides. Bilateral BC presented more commonly with larger tumors, lobular histology, ER+ status, multicentricity or multifocality, pathogenic variant, and palpable disease. Bilateral BC is not associated with worse DFS than unilateral BC.

Prevalence of specific and recurrent/founder pathogenic variants in BRCA genes in breast and ovarian cancer in North Africa

Background

Elucidation of specific and recurrent/founder pathogenic variants (PVs) in BRCA (BRCA1 and BRCA2) genes can make the genetic testing, for breast cancer (BC) and/or ovarian cancer (OC), affordable for developing nations.

Methods

To establish the knowledge about BRCA PVs and to determine the prevalence of the specific and recurrent/founder variants in BRCA genes in BC and/or OC women in North Africa, a systematic review was conducted in Morocco, Algeria, and Tunisia.

Results

Search of the databases yielded 25 relevant references, including eleven studies in Morocco, five in Algeria, and nine in Tunisia. Overall, 15 studies investigated both BRCA1 and BRCA2 genes, four studies examined the entire coding region of the BRCA1 gene, and six studies in which the analysis was limited to a few BRCA1 and/or BRCA2 exons. Overall, 76 PVs (44 in BRCA1 and32 in BRCA2) were identified in 196 BC and/or OC patients (129 BRCA1 and 67 BRCA2 carriers). Eighteen of the 76 (23.7%) PVs [10/44 (22.7%) in BRCA1 and 8/32 (25%) in BRCA2] were reported for the first time and considered to be novel PVs. Among those identified as unlikely to be of North African origin, the BRCA1 c.68_69del and BRCA1 c.5266dupC Jewish founder alleles and PVs that have been reported as recurrent/founder variants in European populations (ex: BRCA1 c.181T>G, BRCA1 c1016dupA). The most well characterized PVs are four in BRCA1 gene [c.211dupA (14.7%), c.798_799detTT (14%), c.5266dup (8.5%), c.5309G>T (7.8%), c.3279delC (4.7%)] and one in BRCA2 [c.1310_1313detAAGA (38.9%)]. The c.211dupA and c.5309G>T PVs were identified as specific founder variants in Tunisia and Morocco, accounting for 35.2% (19/54) and 20.4% (10/49) of total established BRCA1 PVs, respectively. c.798_799delTT variant was identified in 14% (18/129) of all BRCA1 North African carriers, suggesting a founder allele. A broad spectrum of recurrent variants including BRCA1 3279delC, BRCA1 c.5266dup and BRCA2 c.1310_1313detAAGA was detected in 42 patients. BRCA1 founder variants explain around 36.4% (47/129) of BC and outnumber BRCA2 founder variants by a ratio of ≈3:1.

Conclusions

Testing BC and/or OC patients for the panel of specific and recurrent/founder PVs might be the most cost-effective molecular diagnosis strategy.

Genetic Drivers of Ileal Neuroendocrine Tumors

Simple Summary

Although ileal neuroendocrine tumors are the most common tumors of the small intestine, they are not well-defined at the genetic level. Unlike most cancers, they have an unusually low number of mutations, and also lack recurrently mutated genes. Moreover ileal NETs have been difficult to study in the laboratory because there were no animal models and because cell lines were generally unavailable. But recent advances, including the first ileal NET mouse model as well as methods for culturing patient tumor samples, have been described and have already helped to identify IGF2 and CDK4 as two of the genetic drivers for this tumor type. These advances may help in the development of new treatments for patients.

Abstract

The genetic causes of ileal neuroendocrine tumors (ileal NETs, or I-NETs) have been a mystery. For most types of tumors, key genes were revealed by large scale genomic sequencing that demonstrated recurrent mutations of specific oncogenes or tumor suppressors. In contrast, genomic sequencing of ileal NETs demonstrated a distinct lack of recurrently mutated genes, suggesting that the mechanisms that drive the formation of I-NETs may be quite different than the cell-intrinsic mutations that drive the formation of other tumor types. However, recent mouse studies have identified the IGF2 and RB1 pathways in the formation of ileal NETs, which is supported by the subsequent analysis of patient samples. Thus, ileal NETs no longer appear to be a cancer without genetic causes.

Application of Multilayer Evidence for Annotation of C-Terminal BRCA2 Variants

Simple Summary

The potential pathogenic role of germline BRCA2 c.9976A>T and c.10095delinsGAATTATATCT was evaluated in hereditary breast and ovarian cancer (HBOC) patients by investigating 2491 probands and verified in an independent cohort of 122,209 patients. Although the c.10095delinsGAATTATATCT variant was more prevalent among patients compared to control populations, no increased risk for cancer was found. No association between c.9976A>T and clinicopathological parameters or elevated risk for HBOC cases was detected. However, lung cancer was more prevalent in families carrying c.9976A>T compared to pathogenic BRCA1/BRCA2 carrier families. An increased frequency of pancreatic cancer was found in families where c.9976A>T occurred together with other pathogenic BRCA1 variants. The C-terminal stop codon variants showed no association with other pathogenic BRCA2 variants. No loss of heterozygosity (LOH) in tumor tissue and no allelic imbalance in RNA level were confirmed. The c.9976A>T variant may be considered as a potential risk for lung cancer, and a potential modifying factor in pancreatic cancer when it occurs along with the pathogenic BRCA1 variant, although this observation should be validated in a larger sample cohort.

Abstract

The clinical relevance of the BRCA2 C-terminal stop codon variants is controversial. The pathogenic role of the germline BRCA2 c.9976A>T and c.10095delinsGAATTATATCT variants in hereditary breast and ovarian cancer (HBOC) patients was evaluated. An association with clinicopathological parameters was performed in 2491 independent probands diagnosed with HBOC and in 122,209 cancer patients reported earlier. Loss-of-heterozygosity (LOH) in tumor samples and allelic imbalance in RNA extracted from peripheral blood cells were investigated. Neither c.10095delinsGAATTATATCT or c.9976A>T variants showed significant association with clinicopathological parameters or elevated risk for HBOC-associated tumors. Lung cancer was more prevalent in families carrying the c.9976A>T variant compared to pathogenic BRCA1 or BRCA2 carrier families. An increased prevalence of pancreatic cancer was found in families where c.9976A>T occurred together with other pathogenic BRCA1 variants. An increased risk for familial pancreatic, lung and upper aero-digestive tract cancers was confirmed in the validation set. Regarding BRCA2 C-terminal variants, no linkage with other pathogenic BRCA2 variants, no LOH in tumor tissue and no allelic imbalance in RNA level were confirmed. The c.9976A>T variant may be considered as a potential risk for lung cancer, and a potential modifying factor in pancreatic cancer when it occurs along with the pathogenic BRCA1 variant, although this observation should be validated in a larger sample cohort.

Multifocal breast cancers are more prevalent in BRCA2 versus BRCA1 mutation carriers

Multifocal (MF)/multicentric (MC) breast cancer is generally considered to be where two or more breast tumours are present within the same breast, and is seen in ~10% of breast cancer cases. This study investigates the prevalence of multifocality/multicentricity in a cohort of BRCA1/2 mutation carriers with breast cancer from Northern Ireland via cross-sectional analysis. Data from 211 women with BRCA1/2 mutations (BRCA1-91, BRCA2-120) and breast cancer were collected including age, tumour focality, size, type, grade and receptor profile. The prevalence of multifocality/multicentricity within this group was 25% but, within subgroups, prevalence amongst BRCA2 carriers was more than double that of BRCA1 carriers (p = 0.001). Women affected by MF/MC tumours had proportionately higher oestrogen receptor positivity (p = 0.001) and lower triple negativity (p = 0.004). These observations are likely to be driven by the higher BRCA2 mutation prevalence observed within this cohort. The odds of a BRCA2 carrier developing MF/MC cancer were almost four-fold higher than a BRCA1 carrier (odds ratio: 3.71, CI: 1.77-7.78, p = 0.001). These findings were subsequently validated in a second, large independent cohort of patients with BRCA-associated breast cancers from a UK-wide multicentre study. This confirmed a significantly higher prevalence of MF/MC tumours amongst BRCA2 mutation carriers compared with BRCA1 mutation carriers. This has important implications for clinicians involved in the treatment of BRCA2-associated breast cancer, both in the diagnostic process, in ensuring that tumour focality is adequately assessed to facilitate treatment decision-making, and for breast surgeons, particularly if breast conserving surgery is being considered as a treatment option for these patients.

Determination of Pathogenicity of Breast Cancer 1 Gene Variants using the American College of Medical Genetics and Genomics and the Association for Molecular Pathology Guidelines

Objectives

Molecular diagnostic laboratories screen for mutations in disease-causing genes in order to confirm a clinical diagnosis. The classification of DNA variants as 'pathogenic' or 'likely pathogenic' mutations creates a workflow bottleneck, which becomes increasingly challenging as greater number of genes are screened. The classification challenge is also acute if there are conflicting reports regarding pathogenicity and differing classification criteria between laboratories. This study aimed to compare two procedures for the classification of variants in the breast cancer (BRCA)1 gene.

Methods

This bioinformatic study was conducted at LabPLUS, Auckland, New Zealand, from February to June 2017. DNA was extracted from peripheral blood samples of 30 patients and gene library construction was carried out using a commercially available targeted panel for the BRCA1 and BRCA2 genes. The genes were subsequently sequenced and the sequence data analysed. The guidelines published by the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP) provides a comprehensive framework for the interpretation of variants in genes that are associated with Mendelian disorders. The use of these guidelines were compared to the variant classifications that were achieved by reference to those reported in the BRCA Exchange database.

Results

The results showed concordance between the two classification protocols for a panel of 30 BRCA1 gene variants, although the transparency in following the ACMG/AMP guidelines provides a diagnostic laboratory with a generalisable approach that allows laboratory-directed revisions to be undertaken in light of new information.

Conclusion

The ACMG/AMP-based guidelines were applied to a cohort of patients with BRCA1 gene variants. The use of these guidelines provides a system which creates consistency in variant interpretation and supports subsequent clinical management.

Non-BRCA1/2 Variants Detected in a High-Risk Chilean Cohort With a History of Breast and/or Ovarian Cancer

METHODS

Data were retrospectively collected from the registry of the High-Risk Breast and Ovarian Cancer Program at Clínica Las Condes, Santiago, Chile. Data captured included index case diagnosis, ancestry, family history, and genetic test results.

RESULTS

Three hundred fifteen individuals underwent genetic testing during the study period. The frequency of germline pathogenic and likely pathogenic variants in a breast or ovarian cancer predisposition gene was 20.3%. Of those patients who underwent testing with a panel of both high- and moderate-penetrance genes, 10.5% were found to have pathogenic or likely pathogenic variants in non-BRCA1/2 genes.

CONCLUSION

Testing for non-BRCA1 and -2 mutations may be clinically relevant for individuals who are suspected to have a hereditary breast or ovarian cancer syndrome in Chile. Comprehensive genetic testing of individuals who are at high risk is necessary to further characterize the genetic susceptibility to cancer in Chile.

Immunohistochemical features of multifocal and multicentric lobular breast carcinoma

PURPOSE

Patient age, tumor size, axillary lymph node status, expression of estrogen, progesterone and HER2 receptors, as well as the histological grade, are widely accepted prognostic and predictive parameters in breast carcinoma. In invasive lobular carcinoma (ILC), the prognostic factors, such as nodal status and tumor size are believed to be the most valuable ones. The aim of this was set to determine the possible linkage between MFity/MCity of ILC and immunohistochemical predictive (ER, PR, HER2) and prognostic parameters (BRCA1, p53, E-cadherin, Ki-67).

MATERIAL/METHODS

Out of 2486 cases diagnosed with BC from south-eastern Serbia, the presence ILC was noted in 334 cases. Immunohistochemical characterization of predictive and prognostic parameters in ILC was done.

RESULTS

The occurrence of multifocal (MFC) and multicentric carcinoma (MCC) was observed in 18.9% of ILC. Bilateral (BL) BCs were found to be statistically significantly more frequent in younger women, compared to those with MFC, MCC or nonMFC/MCC/BL. No significant correlation was found between MFC/MCC and the presence of axillary lymph node metastases, and expression of immunohistochemical predictive and prognostic parameters. Based on literature data and the findings from the current work, MFity/MCtiy might represent negative morphologic prognostic parameters in ILC.

CONCLUSIONS

In 334 cases analyzed, no statistically significant correlations were observed between MF/MC and the expression of immunohistochemical predictive and prognostic parameters.

Spectrum and frequencies of BRCA1/2 mutations in Bulgarian high risk breast cancer patients

BACKGROUND

About 3885 women are diagnosed with breast cancer and 1285 die from the disease each year in Bulgaria. However no genetic testing to identify the mutations in high-risk families has been provided so far.

METHODS

We evaluated 200 Bulgarian women with primary invasive breast cancer and with personal/ family history of breast cancer for the presence of unequivocally damaging germline mutations in BRCA1/2 using Sanger sequencing.

RESULTS

Of the 200 patients, 39 (19.5 %) carried a disease predisposing mutation, including 28 (14 %) with a BRCA1 mutation and 11 (5.5 %) with a BRCA2 mutation. At BRCA1, 6 different mutations were identified, including 2 frameshifts, 1 nonsense and 1 missense that had been previously reported (c.5030_5033delCTAA, c.5263_5264insC, c.4603G > T, c.181 T > G), and 2 frameshifts, which were novel to this study (c.464delA, c.5397_5403delCCCTTGG). At BRCA2, 7 different frameshift mutations were identified, including 5 previously reported (5851_5854delAGTT, c.5946delT, c.5718_5719delCT, c.7910_7914delCCTTT,c.9098_9099insA) and 2 novel (c.8532_8533delAA, c.9682delA). A BRCA1 mutation was found in 18.4 % of women diagnosed with breast cancer at/or under the age of 40 compared to 11.2 % of women diagnosed at a later age; a BRCA2 mutation was found in 4 % of women diagnosed at/or under the age of 40 compared to 6.5 % of women diagnosed at a later age. A mutation was present in 26.8 % patients with a positive family history and in 14.4 % of women with a negative family history. The most prevalent mutation observed in 22 patients (11 %) was BRCA1 c.5263_5264insC, a known Slavic mutation with founder effect in Eastern European and AJ communities. Other recurrent mutations were BRCA2 c.9098-9099insA (2 %), BRCA1 c.181T > G (1 %) and BRCA2 c.5851_5854delAGTT (1 %). Notably, BRCA1 c.5263_5264insC represented 56 % of all mutations identified in this series. Of the 22 patients with BRCA1 c.5263_5264insC, 9 were diagnosed with early onset breast cancer, 11 with TNBCs, 4 with bilateral breast cancer, and 6 with both breast and ovarian cancer.

CONCLUSIONS

This is the first comprehensive study of the BRCA1/2 mutation spectrum in Bulgaria and will assist the establishment of efficient protocols for genetic testing and individualized risk assessment for Bulgarian breast/ovarian cancer patients and healthy individuals at a high-risk.

Are synchronous and metachronous bilateral breast cancers different? An immunohistochemical analysis aimed at intrinsic tumor phenotype

The biology and pathomechanism of bilateral breast cancers is not fully understood. We compared the morphological and immunohistochemical characteristics of primary tumors in patients with synchronous bilateral breast cancers and metachronous bilateral breast cancers, with special focus on intrinsic tumor phenotype.

METHODS

Tumor morphology and expression of 8 immunohistochemical markers were assessed in tissue microarrays containing primary breast tumor cores from 113 metachronous bilateral breast cancers and 61 synchronous bilateral breast cancers. Analyzed markers included hormone receptors (estrogen receptor, progesterone receptor), HER2, Ki67, cytokeratin 5/6, E-cadherin, vimentin and epidermal growth factor receptor. Cutoff levels are provided in the table.

RESULTS

Metachronous bilateral breast cancers tumors had lower estrogen receptor expression (p=0.047) and higher expression of cytokeratin 5/6 (p=0.017) and of vimentin (p=0.008); in multivariate analysis only vimentin retained the significance (p=0.01). Ten (13%) and 11 (26%) of metachronous bilateral breast cancers and synchronous bilateral breast cancers had luminal A phenotype, 39 (50%) and 15 (36%) were luminal B HER2-negative, 13 (17%) and 12 (28%) - luminal B HER2-positive, 3 (4%) and 2 (5%) - HER2-positive (not luminal), and 12 (16%) and 2 (5%) had triple negative phenotype (p=0.07).

CONCLUSION

Metachronous bilateral breast cancers, compared to synchronous bilateral breast cancers, are characterized by more aggressive phenotype, expressed by lower expression of estrogen receptor and stronger expression of cytokeratin 5/6 and vimentin; this does not, however, translate into differences in the distribution of intrinsic tumor phenotypes.

Functional assays for analysis of variants of uncertain significance in BRCA2

Missense variants in the BRCA2 gene are routinely detected during clinical screening for pathogenic mutations in patients with a family history of breast and ovarian cancer. These subtle changes frequently remain of unknown clinical significance because of the lack of genetic information that may help establish a direct correlation with cancer predisposition. Therefore, alternative ways of predicting the pathogenicity of these variants are urgently needed. Since BRCA2 is a protein involved in important cellular mechanisms such as DNA repair, replication, and cell cycle control, functional assays have been developed that exploit these cellular activities to explore the impact of the variants on protein function. In this review, we summarize assays developed and currently utilized for studying missense variants in BRCA2. We specifically depict details of each assay, including variants of uncertain significance analyzed, and describe a validation set of (genetically) proven pathogenic and neutral missense variants to serve as a golden standard for the validation of each assay. Guidelines are proposed to enable implementation of laboratory-based methods to assess the impact of the variant on cancer risk.

Functional analysis of BRCA1 missense variants of uncertain significance in Japanese breast cancer families

Germline mutations in the tumor suppressor genes BRCA1 and BRCA2 are responsible for a large proportion of familial breast cancer cases, and therefore, BRCA1 and BRCA2 genetic testing has become increasingly common in clinical practice. However, variants of uncertain significance (VUS) have been detected in 16.3% of Japanese patients suspected of having hereditary breast and ovarian cancers. The clinical importance of VUS is unknown, and their incidence has led to issues in risk counseling, assessment and treatment of cancer patients. In the present study, we performed functional analyses of two VUS in BRCA1, A1752G and Y1853C that were detected in two independent breast cancer patients who were suspected of having hereditary breast cancer. Segregation analysis revealed that Y1853C, but not A1752G, was cosegregated in affected family members. Conservation, transcription and structure analyses also supported the pathogenic potential of Y1853C. Detailed segregation and in silico and in vitro analyses will enhance our understanding of VUS and improve the management of cancer patients and their families.

Are bilateral breast cancers different from breast cancers coexisting with ovarian cancer? An immunohistochemical analysis aimed at intrinsic tumor phenotype

RATIONALE

Bilateral breast cancers (BBC) and breast cancers coexisting with ovarian cancer (BOCS) are associated with genetic predisposition more frequently than sporadic cases. We compared the phenotypes of these tumors to better understand their pathomechanisms and aid the guiding of their clinical management.

MATERIALS AND METHODS

Tumor morphology and expression of ER, PgR, HER2, Ki67, CK5/6, E-cadherin, vimentin and EGFR were assessed in a tissue microarray containing cores from 174 BBC, 23 BOCS and 2 BBC + BOCS.

RESULTS

BOCS tumors were characterized by higher incidence of EGFR expression, HER2 negativity and lower incidence of intraductal component. HER2-positive phenotypes were marginally more frequent in the BBC group and triple negative tumors - in BOCS.

CONCLUSION

Breast cancers from BOCS patients are characterized by more aggressive phenotype, most probably related to their more frequent association with BRCA1 mutation.

Analysis of 30 putative BRCA1 splicing mutations in hereditary breast and ovarian cancer families identifies exonic splice site mutations that escape in silico prediction

Screening for pathogenic mutations in breast and ovarian cancer genes such as BRCA1/2, CHEK2 and RAD51C is common practice for individuals from high-risk families. However, test results may be ambiguous due to the presence of unclassified variants (UCV) in the concurrent absence of clearly cancer-predisposing mutations. Especially the presence of intronic or exonic variants within these genes that possibly affect proper pre-mRNA processing poses a challenge as their functional implications are not immediately apparent. Therefore, it appears necessary to characterize potential splicing UCV and to develop appropriate classification tools. We investigated 30 distinct BRCA1 variants, both intronic and exonic, regarding their spliceogenic potential by commonly used in silico prediction algorithms (HSF, MaxEntScan) along with in vitro transcript analyses. A total of 25 variants were identified spliceogenic, either causing/enhancing exon skipping or activation of cryptic splice sites, or both. Except from a single intronic variant causing minor effects on BRCA1 pre-mRNA processing in our analyses, 23 out of 24 intronic variants were correctly predicted by MaxEntScan, while HSF was less accurate in this cohort. Among the 6 exonic variants analyzed, 4 severely impair correct pre-mRNA processing, while the remaining two have partial effects. In contrast to the intronic alterations investigated, only half of the spliceogenic exonic variants were correctly predicted by HSF and/or MaxEntScan. These data support the idea that exonic splicing mutations are commonly disease-causing and concurrently prone to escape in silico prediction, hence necessitating experimental in vitro splicing analysis.

Breast cancer in young women in a limited-resource environment

BACKGROUND

Despite the higher incidence of breast cancer in young women in developing countries, there is a paucity of data on their management. We present the clinicopathological features and outcome of treatment of women 35 years or younger with breast cancer in a resource-restricted environment.

METHODS

A total of 141 patients who were diagnosed with primary breast cancer at 35 years or younger from January 2000 to June 2008 were retrieved from the cancer registry of a breast clinic at a tertiary hospital and a private breast health center in South Africa. Clinicopathological features, treatment, and survival were analyzed.

RESULTS

Two patients presented with TNM stage 0 (1.4%), 14 with stage I (9.9%), 47 with stage II (33.35%), 47 with stage III (33.3%), and 31 with stage IV (21.9%). Tumor grade was 3 in 47%, grade 2 in 37%, and grade 1 in 16% of patients. One hundred and four patients with stage 0-III disease underwent treatment with curative intent, 83 had a mastectomy, and 12 had breast-conserving surgery. Ninety patients (86.5%) had chemotherapy, 68 (65.4%) had radiotherapy, and 50 (48.1%) had hormonal therapy. Of 93 patients who completed primary therapy, 4 developed contralateral cancers, 3 had locoregional recurrence, 8 developed synchronous locoregional and distant recurrence, and 19 relapsed with distant metastasis only. The 2-year disease-free and overall survival for stage 0-III disease was 48 and 56%, respectively.

CONCLUSIONS

Young women with breast cancer in a resource-limited environment have similar adverse clinicopathological features to those in developed countries. Their disease is more advanced at presentation with poorer outcome. Increased awareness, better systemic therapy, and more comprehensive genetic studies are essential to improve the dismal outcome.

Founder BRCA1/2 mutations in the Europe: implications for hereditary breast-ovarian cancer prevention and control

Detection of mutations in hereditary breast and ovarian cancer-related BRCA1 and BRCA2 genes is an effective method of cancer prevention and early detection. Different ethnic and geographical regions have different BRCA1 and BRCA2 mutation spectrum and prevalence. Along with the emerging targeted therapy, demand and uptake for rapid BRCA1/2 mutations testing will increase in a near future. However, current patients selection and genetic testing strategies in most countries impose significant lag in this practice. The knowledge of the genetic structure of particular populations is important for the developing of effective screening protocol and may provide more efficient approach for the individualization of genetic testing. Elucidating of founder effect in BRCA1/2 genes can have an impact on the management of hereditary cancer families on a national and international healthcare system level, making genetic testing more affordable and cost-effective. The purpose of this review is to summarize current evidence about the BRCA1/2 founder mutations diversity in European populations.

Impact of x chromosome genes in explaining the excess risk of cancer in males

The authors examined cancer incidence sex ratios in Denmark for 1943-2003 by age group. At nongenital/nonbreast sites, incidences were consistently higher in males. While environmental factors dominate cancer risk, the authors hypothesized that the higher risk in males might be explained by unspecified X chromosome genes' protecting female cells from genotoxic damage. If so, cancer susceptibility would be passed from parent to offspring differently by sex. The authors compared relative risks in offspring of parents with and without cancer histories. For all comparisons, relative risks were similar in offspring of fathers with cancer (relative risk (RR) = 1.14, 95% confidence interval: 1.08, 1.20). Risks in offspring were higher for parents diagnosed before age 50 years and for cancers at the same site rather than different sites. Genital cancer risks were increased in same-sex offspring of parents with genital cancers. Breast cancer risks were high in both daughters (RR = 2.37) and sons (RR = 4.63) of mothers with breast cancer and in daughters (RR = 5.96) of fathers with breast cancer. Thus, X chromosome genetic factors were not responsible for the excess risk of cancer in males. Susceptibility to genital cancer was increased in same-sex offspring, and breast cancer risks were increased in both sons and daughters when either parent had had breast cancer.

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 dependent on whether a mutation is identified in an affected relative.

BRCA1 and BRCA2 mutation prevalence and clinical characteristics of a population-based series of ovarian cancer cases from Denmark

PURPOSE

To evaluate the prevalence of BRCA1 and BRCA2 mutations and associations with clinical correlates of disease in a population-based series of ovarian cancer cases from Denmark.

METHODS

DNA sequencing and multiplex ligation-dependent probe amplification analysis were used to analyze the BRCA1 and BRCA2 genes for coding sequence mutations and large genomic rearrangements in 445 confirmed cases of ovarian cancer. We evaluated associations between mutation status and clinical characteristics, including cancer risks for first-degree relatives and clinicopathologic features of tumors.

RESULTS

Deleterious BRCA1 or BRCA2 mutations were identified in 26 cases; thus, mutations in these genes are responsible for at least 5.8% of ovarian cancer cases in this population. Five different mutations were identified in more than one individual, suggesting that they may be founder mutations in Denmark. We identified several differences between mutation carriers and noncarriers: mutation carriers were diagnosed at a significantly early age (median, 49 and 61 years, respectively; P = 0.0001); the frequency of BRCA1 mutation carriers was 23% for women diagnosed <40 years, 15% for 40 to 49 years, 4% for 50 to 59 years, and 2% for > or =60 years (P = 0.00002); ovarian cancer in carriers was diagnosed at a later stage (P = 0.002) and tumors were of poorer grade (P = 0.0001); and first-degree relatives of mutation carriers had greater relative risks of both ovarian cancer [10.6 (95% confidence interval, 4.2-26.6); P < 0.0001] and breast cancer <60 years [8.7 (95% confidence interval, 3.0-25.0); P < 0.0001].

CONCLUSION

These data may have a significant effect on risk assessment and clinical management of individuals from Denmark who are predisposed to ovarian cancer because they carry a BRCA1 or BRCA2 mutation.

BRCA1 and BRCA2 mutations in Danish families with hereditary breast and/or ovarian cancer

A national study of BRCA1 and BRCA2 mutations in Danish HBOC (Hereditary Breast Ovarian Cancer) families revealed a total number of 322 mutation positive families, 206 (64%) BRCA1 and 116 (36%) BRCA2 positive families from a population of 5.5 million inhabitants. Seven hundred and twenty six mutation positive individuals were identified: 402 female BRCA1 carriers, 79 male BRCA1 carriers, 213 female BRCA2 carriers, and 32 male BRCA2 carriers by April 2006. Most of the mutations were frame shift or nonsense mutations, while large genomic rearrangements were rare. Most mutations were only identified in one family. A few mutations were detected repeatedly. In BRCA1 the most common mutations were: 2594delC in 32 families (16%), 3438G>T in 19 families (9%), 5382insC in 16 families (8%), 3829delT in 11 families (5%). In BRCA2 the most common mutations were: 6601delA in 13 families (11%), 1538del4 in 12 families (10%), 6714del4 in 10 families (9%). There was a tendency towards a higher frequency of BRCA2 mutations in West Denmark compared to East Denmark. The frequencies of specific BRCA1 and BRCA2 mutations were slightly different in the two regions. The mutations occurring in West Denmark have also been observed in other Scandinavian countries whereas the mutations occurring in East Denmark were more often reported from other European countries and the Baltic countries. The pattern of mutation distributions are comparable with observations from other Scandinavian and European studies and indicate that the Danish BRCA1 and BRCA2 mutations are a mixture of Scandinavian mutations and other European mutations including two of the Ashkenazi mutations. Even though a tendency towards founder mutations was observed most mutations were only detected once. Based on these observations we recommend that the mutation screening strategy of the BRCA1 and BRCA2 genes in Danish HBOC families comprises full screening of both genes including analysis for large genomic rearrangements.

Occurrence of both breast and ovarian cancer in a woman is a marker for the BRCA gene mutations: a population-based study from western Sweden

AIM

This study aimed to analyze whether the occurrence of both breast and ovarian cancer in a woman serves as a marker for BRCA gene mutations.

MATERIAL AND METHODS

This population-based study included 256 women in western Sweden who developed both invasive breast and ovarian tumors between 1958 and 1999. Archival paraffin tissue blocks of their tumors were retrieved for DNA-extraction to analyze the founder mutation, BRCA1 c.3171_3175dup (c.3171ins5), which is most common in this geographic area and four other common Scandinavian BRCA1 gene mutations and one BRCA2 mutation. Together, account these mutations for approximately 75% of the BRCA1/2 gene mutations in the clinical unit.

RESULTS

Ninteen percent (95% confidence interval (CI) 14-24%) of the women carried one of the analyzed BRCA1 gene mutations but none of the women were positive for the analyzed BRCA2 mutation. One-third of the women with both tumors before age 60 were mutation carriers. BRCA1 c.3171_3175dup (c.3171ins5) constituted 84% of all identified mutations. Although the majority of breast cancers were invasive ductal and atypical medullary types, a variety of other breast malignancies were seen among mutation carriers. Serous ovarian carcinomas predominated among ovarian tumors. A variety of other ovarian tumors, including three granulosa-theca cell tumors, were also observed among mutation carriers.

CONCLUSIONS

The occurrence of both breast and ovarian cancer in a woman is associated with a high likelihood of a constitutional BRCA1 mutation. These women and their families might therefore be considered for mutation screening after appropriate genetic counselling.

Evaluation of two different models to predict BRCA1 and BRCA2 mutations in a cohort of Danish hereditary breast and/or ovarian cancer families

To meet the increasing demand for BRCA1 and BRCA2 mutation analysis, a robust system for selecting families who have a higher chance of a mutation has become important. Several models have been developed to help predict which samples are more likely to be mutation positive than others. We have undertaken a complete BRCA1 and BRCA2 mutation analysis in 267 Danish families with high-risk family history. We found deleterious mutations in 28% (76) of the families, 68% (52) of those in BRCA1 and 32% (24) in BRCA2. We compared our results with two popular manual models developed to estimate the chance of a positive result. One is the recently published Manchester model and the other is the Frank 2 model updated by Myriad Genetic Laboratories, Inc. Neither of the models would have suggested screening all mutation-positive samples. The Manchester model would have suggested screening 124 of the families in the cohort, thereby detecting 54 of 76 mutations (sensitivity 71%; specificity 63%), whereas the Frank 2/Myriad model would have found 60 of 76 mutations by screening 169 samples if a 10% likelihood was adapted (sensitivity 79%; specificity 43%). The updated Manchester model suggested screening 172 families whereby 64 mutations would have been detected (sensitivity 84%; specificity 44%). We conclude that although both models would have reduced the number of samples screened significantly, up to 28% of the mutations would not have been found by applying these models to this Danish cohort of families. This raises the question whether models designed for specific populations can be used in a wider setting.

Genetic implications of bilateral breast cancer: a population based cohort study

BACKGROUND

Women with breast cancer are at high risk of bilateral breast cancer. We aimed to assess the incidence of bilateral breast cancer in relation to age and time since diagnosis of first cancer.

METHODS

We analysed a population-based cohort of 123757 women with a first primary breast cancer diagnosed in Sweden from 1970 to 2000 for frequency of bilateral breast cancers and deaths by means of record linkage. Second primary breast cancers were categorised as synchronous bilateral breast cancers if diagnosed within 3 months of the first primary cancer or as metachronous if diagnosed more than 3 months after diagnosis of first primary cancer.

FINDINGS

We identified 6550 women who had developed bilateral breast cancer. Age-incidence patterns of synchronous and unilateral breast cancer were similar, although the absolute rates of synchronous bilateral cancer were 50-100 times lower than those of unilateral cancer. A woman aged 80 years or older is at least twice as likely to be diagnosed with synchronous bilateral breast cancer than is a woman younger than 40 years. In the first 20 years after diagnosis of primary breast cancer, incidence of metachronous bilateral cancer decreased from about 800 per 10(5) person-years to 400 per 10(5) person-years in patients diagnosed with primary breast cancer before the age of 45 years, whereas incidence remained at 500-600 per 10(5) person-years in those age 45 years or older at diagnosis. After 30 years' follow-up, cumulative risk of metachronous bilateral breast cancer was about 15% irrespective of age at first primary breast cancer.

INTERPRETATION

The higher than expected risk of synchronous bilateral breast cancer could be explained by non-genetic factors. By contrast, incidence of metachronous bilateral cancer fits neither a model of highly penetrant genes nor aggregation of environmental risk factors.

Clinical, molecular and geographical features of hereditary breast/ovarian cancer in latvia

Introduction

The aim of the study is to evaluate the incidence and phenotype-genotype characteristics of hereditary breast and ovarian cancer syndromes in Latvia in order to develop the basis of clinical management for patients and their relatives affected by this syndrome.

Materials and methods

In 2002-2004 in two Latvian oncology hospitals (Liepãja Oncology Hospital and Daugavpils Oncology Hospital) cancer family histories were collected from 287 consecutive patients with breast and ovarian cancer. In all cases, when it was possible to obtain the blood sample, DNA testing for founder mutations in the BRCA1 gene was performed.

Results

Among 287 family cancer histories analysed in 8 (2.8%) cases criteria of hereditary breast cancer (HBC) were fulfilled and in 5 (1.7%) cases hereditary breast and ovarian cancer (HBOC) was diagnosed. In 50 (17.4%) cases we have suspicion of hereditary breast cancer (HBC susp.) and in 8 (2.8%) cases - suspicion of hereditary breast and ovarian cancer (HBOC susp.). We have one (0.3%) case with hereditary ovarian cancer (HOC). DNA testing of founder mutations in the BRCA1 gene (exon 20 (5382 insC) exon 5 (300T/G), exon 11, 17 (4153delA)) for 178/287 (62%) patients was performed. In 9/287 (4.9%) cases we found a mutation in the BRCA1 gene. 4 mutations were detected in exon 11, 17 (4153delA) and 4 mutations in exon 20 (5382 insC) and 1 in exon 5.

Conclusions

Existing pedigree/clinical data suggest that in Latvia the clinical frequency of hereditary breast and ovarian cancer is around 5% of consecutive breast and ovarian cancer patients and suspicion of the syndrome is observed in another 20% of cases. Frequency of BRCA1 founder mutations is 5% of all consecutive breast and ovarian cancers. Considerable geographical differences in the clinical and molecular frequency of hereditary breast ovarian cancer have been observed in Latvia.

BRCA1 and BRCA2 germline mutation spectrum and frequencies in Belgian breast/ovarian cancer families

Worldwide variation in the distribution of BRCA1 and BRCA2 mutations is well recognised, and for the Belgian population no comprehensive studies about BRCA1/2 mutation spectra or frequencies have been published. We screened the complete coding region of both genes in 451 individuals from 349 Belgian families referred to a family cancer clinic and identified 49 families with a BRCA1 and 26 families with a BRCA2 mutation. Six major recurrent mutations (BRCA1 IVS5+3A>G, 2478–2479insG, E1221X and BRCA2 IVS6+1G>A, 6503-6504delTT, 9132delC) accounted for nearly 60% of all mutations identified. Besides 75 true pathogenic mutations, we identified several variants of unknown clinical significance. In combination with a family history, an early average age of female breast cancer diagnosis (P<0.001), and the presence of a relative with ovarian cancer (P<0.0001) or multiple primary breast cancers (P=0.002), increased the chance for finding a mutation. Male breast cancer was indicative of a BRCA2 mutation segregating in the family (P=0.002). Mutations in the 5′-end of BRCA1 and BRCA2 were associated with a significantly increased risk for ovarian cancer relative to the central portion of the gene. Our study suggests a role for additional breast cancer susceptibility genes in the Belgian population, since mutation detection ratios were low in high-risk breast cancer-only families as compared to breast–ovarian cancer families. Given the large proportion of recurring mutations, molecular testing can now be organised in a more cost-effective way. Our data allow optimisation of genetic counselling and disease prevention in Belgian breast/ovarian cancer families.

BRCA1 and BRCA2 Mutations in Women from Shanghai China

Little is known about the frequency of germ-line mutations in the breast cancer susceptibility genes BRCA1 and BRCA2 among Asian populations. We investigated the distribution of BRCA1 and BRCA2 germ-line mutations and polymorphisms in a cohort of women from Shanghai, China. Study subjects totaled 1306, and included 645 women with breast cancer, 342 women with benign breast disease, and 319 unaffected controls, born between 1924 and 1958, selected from women enrolled in a randomized trial of Breast Self-Examination in Shanghai, China. Women were selected without regard to family history of breast or ovarian cancer. All of the coding regions and exon-intron boundaries were screened. Data were analyzed with respect to age at diagnosis, and family history of breast and ovarian cancer. The prevalence of known disease-associated mutations in women with breast cancer was 1.1% each, for BRCA1 and BRCA2. Among breast cancer cases with a family history of breast or ovarian cancer, 8.1% and 2.7% carried likely BRCA1 and BRCA2 disease-associated mutations, respectively. Overall, these results suggest that inherited susceptibility to breast cancer due to germ-line BRCA1/2 mutations among women with a family history of breast cancer is comparable between women from Shanghai and Caucasian women of Western European descent. Most alterations observed appear unique to the Chinese population, suggesting a resource that will be useful for assessing risk among both Chinese women and United States women of Chinese descent.

Prevalence of BRCA1 and BRCA2 germline mutations in young breast cancer patients: a population-based study

Our aim was to estimate the prevalence of mutations in the BRCA1 and BRCA2 genes among unselected incident cases of breast cancer in young women. We identified 158 incident breast cancer cases diagnosed before age 46 years in predefined geographic areas in Girona and Tarragona, Spain, during 1995-1997. Of these, 136 (86%) provided information on family history of cancer and were screened for BRCA1 and BRCA2 mutations. Nine of the 136 (6.6%) were found to carry BRCA deleterious mutations (MUT) (1 BRCA1 and 8 BRCA2), and 20 were detected with rare BRCA variants of unknown significance (UV). Both MUT and US BRCA alterations were more frequent in younger patients: 7 (11.6%) MUT and 12 (19.3%) UV carriers were found in the group of 62 patients younger than 40 years, whereas 2 (2.7%) MUT and 9 (12%) US carriers were identified in the group of 74 patients aged 40-45. Family history of breast and ovarian cancers suggestive of hereditary condition (at least 2 first- or second-degree relatives affected with breast cancer or at least 1 relative affected with ovarian cancer or early-onset breast cancer) was absent for 5 of 9 MUT carriers. This suggests that BRCA screening policies based on family history of cancer would miss a considerable proportion of BRCA mutations. Mutations in the BRCA1 and BRCA2 genes explain at least 10% of breast cancer cases diagnosed before age 40 years. The contribution of these genes to early-onset breast cancer is likely to be even higher given that certain UV cases might be disease-associated.

Molecular pathogenesis of bilateral breast cancer

Bilateral breast cancer (biBC) offers intriguing possibilities for molecular genetic investigations, however it is disproportionally less studied than its unilateral counterpart. By now, genetic research has succeeded to resolve at least two important aspects of biBC pathogenesis. First, it has been confirmed, that the vast majority if not all biBC arise due to clonally independent events but not due to contralateral metastatic spread. Second, unselected biBC cases have been shown to have a modest prevalence of BRCA germ-line mutations (approximately 5%), although a considerable frequency of BRCA defects (up to 20%) has been observed in early-onset and/or familial forms of the disease. Other data related to biBC appear to be at suggestive stage. Recent reports demonstrate, that the tumors forming biBC pair may show similarities of their molecular portraits, especially if they develop synchronously. This observations imply that the host factors may determine not only the level of breast cancer susceptibility, but also the molecular variant of the disease development. Apart from this, biBC may serve as a very demonstrative case group in the studies of breast cancer predisposing low-penetrance gene polymorphisms, because it is more likely to accumulate unfavorable allele combinations than the unilateral patients. The utility of this approach has been already exemplified by several scientific publications. Further research on the biBC molecular pathogenesis may significantly contribute to the general understanding of the process of malignant transformation.