Publications by authors named "Adalgeir Arason"

36 Publications

The predictive ability of the 313 variant-based polygenic risk score for contralateral breast cancer risk prediction in women of European ancestry with a heterozygous BRCA1 or BRCA2 pathogenic variant.

Genet Med 2021 Jun 10. Epub 2021 Jun 10.

Department of Cancer Epidemiology and Genetics, Masaryk Memorial Cancer Institute, Brno, Czech Republic.

Purpose: To evaluate the association between a previously published 313 variant-based breast cancer (BC) polygenic risk score (PRS) and contralateral breast cancer (CBC) risk, in BRCA1 and BRCA2 pathogenic variant heterozygotes.

Methods: We included women of European ancestry with a prevalent first primary invasive BC (BRCA1 = 6,591 with 1,402 prevalent CBC cases; BRCA2 = 4,208 with 647 prevalent CBC cases) from the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA), a large international retrospective series. Cox regression analysis was performed to assess the association between overall and ER-specific PRS and CBC risk.

Results: For BRCA1 heterozygotes the estrogen receptor (ER)-negative PRS showed the largest association with CBC risk, hazard ratio (HR) per SD = 1.12, 95% confidence interval (CI) (1.06-1.18), C-index = 0.53; for BRCA2 heterozygotes, this was the ER-positive PRS, HR = 1.15, 95% CI (1.07-1.25), C-index = 0.57. Adjusting for family history, age at diagnosis, treatment, or pathological characteristics for the first BC did not change association effect sizes. For women developing first BC < age 40 years, the cumulative PRS 5th and 95th percentile 10-year CBC risks were 22% and 32% for BRCA1 and 13% and 23% for BRCA2 heterozygotes, respectively.

Conclusion: The PRS can be used to refine individual CBC risks for BRCA1/2 heterozygotes of European ancestry, however the PRS needs to be considered in the context of a multifactorial risk model to evaluate whether it might influence clinical decision-making.
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http://dx.doi.org/10.1038/s41436-021-01198-7DOI Listing
June 2021

Transcriptome-wide association study of breast cancer risk by estrogen-receptor status.

Genet Epidemiol 2020 07 1;44(5):442-468. Epub 2020 Mar 1.

Department of Radiation Oncology, Hannover Medical School, Hannover, Germany.

Previous transcriptome-wide association studies (TWAS) have identified breast cancer risk genes by integrating data from expression quantitative loci and genome-wide association studies (GWAS), but analyses of breast cancer subtype-specific associations have been limited. In this study, we conducted a TWAS using gene expression data from GTEx and summary statistics from the hitherto largest GWAS meta-analysis conducted for breast cancer overall, and by estrogen receptor subtypes (ER+ and ER-). We further compared associations with ER+ and ER- subtypes, using a case-only TWAS approach. We also conducted multigene conditional analyses in regions with multiple TWAS associations. Two genes, STXBP4 and HIST2H2BA, were specifically associated with ER+ but not with ER- breast cancer. We further identified 30 TWAS-significant genes associated with overall breast cancer risk, including four that were not identified in previous studies. Conditional analyses identified single independent breast-cancer gene in three of six regions harboring multiple TWAS-significant genes. Our study provides new information on breast cancer genetics and biology, particularly about genomic differences between ER+ and ER- breast cancer.
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http://dx.doi.org/10.1002/gepi.22288DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7987299PMC
July 2020

Fine-mapping of 150 breast cancer risk regions identifies 191 likely target genes.

Nat Genet 2020 01 7;52(1):56-73. Epub 2020 Jan 7.

Unit of Medical Genetics, Department of Medical Oncology and Hematology, Fondazione IRCCS Istituto Nazionale dei Tumori di Milano, Milan, Italy.

Genome-wide association studies have identified breast cancer risk variants in over 150 genomic regions, but the mechanisms underlying risk remain largely unknown. These regions were explored by combining association analysis with in silico genomic feature annotations. We defined 205 independent risk-associated signals with the set of credible causal variants in each one. In parallel, we used a Bayesian approach (PAINTOR) that combines genetic association, linkage disequilibrium and enriched genomic features to determine variants with high posterior probabilities of being causal. Potentially causal variants were significantly over-represented in active gene regulatory regions and transcription factor binding sites. We applied our INQUSIT pipeline for prioritizing genes as targets of those potentially causal variants, using gene expression (expression quantitative trait loci), chromatin interaction and functional annotations. Known cancer drivers, transcription factors and genes in the developmental, apoptosis, immune system and DNA integrity checkpoint gene ontology pathways were over-represented among the highest-confidence target genes.
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http://dx.doi.org/10.1038/s41588-019-0537-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6974400PMC
January 2020

Association of Genomic Domains in and with Prostate Cancer Risk and Aggressiveness.

Cancer Res 2020 02 13;80(3):624-638. Epub 2019 Nov 13.

Unité de Prévention et d'Epidémiologie Génétique, Centre Léon Bérard, Lyon, France.

Pathogenic sequence variants (PSV) in or () are associated with increased risk and severity of prostate cancer. We evaluated whether PSVs in were associated with risk of overall prostate cancer or high grade (Gleason 8+) prostate cancer using an international sample of 65 and 171 male PSV carriers with prostate cancer, and 3,388 and 2,880 male PSV carriers without prostate cancer. PSVs in the 3' region of (c.7914+) were significantly associated with elevated risk of prostate cancer compared with reference bin c.1001-c.7913 [HR = 1.78; 95% confidence interval (CI), 1.25-2.52; = 0.001], as well as elevated risk of Gleason 8+ prostate cancer (HR = 3.11; 95% CI, 1.63-5.95; = 0.001). c.756-c.1000 was also associated with elevated prostate cancer risk (HR = 2.83; 95% CI, 1.71-4.68; = 0.00004) and elevated risk of Gleason 8+ prostate cancer (HR = 4.95; 95% CI, 2.12-11.54; = 0.0002). No genotype-phenotype associations were detected for PSVs in . These results demonstrate that specific PSVs may be associated with elevated risk of developing aggressive prostate cancer. SIGNIFICANCE: Aggressive prostate cancer risk in BRCA2 mutation carriers may vary according to the specific BRCA2 mutation inherited by the at-risk individual.
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http://dx.doi.org/10.1158/0008-5472.CAN-19-1840DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7553241PMC
February 2020

The c.4096+3A>G Variant Displays Classical Characteristics of Pathogenic Mutations in Hereditary Breast and Ovarian Cancers, But Still Allows Homozygous Viability.

Genes (Basel) 2019 11 1;10(11). Epub 2019 Nov 1.

Department of Pathology, Landspitali - The National University Hospital of Iceland, 101 Reykjavik, Iceland.

Mutations in result in predisposal to breast and ovarian cancers, but many variants exist with unknown clinical significance (VUS). One is c.4096+3A>G, which affects production of the full-length transcript, while augmenting transcripts lacking most or all of exon 11. Nonetheless, homozygosity of this variant has been reported in a healthy woman. We saw this variant cosegregate with breast and ovarian cancer in several family branches of four Icelandic pedigrees, with instances of phenocopies and a homozygous woman with lung cancer. We found eight heterozygous carriers (0.44%) in 1820 unselected breast cancer cases, and three (0.15%) in 1968 controls ( = 0.13). Seeking conclusive evidence, we studied tumors from carriers in the pedigrees for wild-type-loss of heterozygosity (wtLOH) and -characteristic prevalence of estrogen receptor (ER) negativity. Of 15 breast and six ovarian tumors, wtLOH occurred in nine breast and all six ovarian tumours, and six of the nine breast tumors with wtLOH were ER-negative. These data accord with a pathogenic -mutation. Our findings add to the current knowledge of and the role of its exon 11 in cancer pathogenicity, and will be of use in clinical genetic counselling.
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http://dx.doi.org/10.3390/genes10110882DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6896150PMC
November 2019

High expression of the vacuole membrane protein 1 (VMP1) is a potential marker of poor prognosis in HER2 positive breast cancer.

PLoS One 2019 23;14(8):e0221413. Epub 2019 Aug 23.

Cell Biology Unit at the Pathology Department, Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland.

Background: Fusion genes result from genomic structural changes, which can lead to alterations in gene expression that supports tumor development. The aim of the study was to use fusion genes as a tool to identify new breast cancer (BC) genes with a role in BC progression.

Methods: Fusion genes from breast tumors and BC cell lines were collected from publications. RNA-Seq data from tumors and cell lines were retrieved from databanks and analyzed for fusions with SOAPfuse or the analysis was purchased. Fusion genes identified in both tumors (n = 1724) and cell lines (n = 45) were confirmed by qRT-PCR and sequencing. Their individual genes were ranked by selection criteria that included correlation of their mRNA level with copy number. The expression of the top ranked gene was measured by qRT-PCR in normal tissue and in breast tumors from an exploratory cohort (n = 141) and a validation cohort (n = 277). Expression levels were correlated with clinical and pathological factors as well as the patients' survival. The results were followed up in BC cohorts from TCGA (n = 818) and METABRIC (n = 2509).

Results: Vacuole membrane protein 1 (VMP1) was the most promising candidate based on specific selection criteria. Its expression was higher in breast tumor tissue than normal tissue (p = 1x10-4), and its expression was significantly higher in HER2 positive than HER2 negative breast tumors in all four cohorts analyzed. High expression of VMP1 associated with breast cancer specific survival (BCSS) in cohort 1 (hazard ratio (HR) = 2.31, CI 1.27-4.18) and METABRIC (HR = 1.26, CI 1.02-1.57), and also after adjusting for HER2 expression in cohort 1 (HR = 2.03, CI 1.10-3.72). BCSS was not significant in cohort 2 or TCGA cohort, which may be due to differences in treatment regimens.

Conclusions: The results suggest that high VMP1 expression is a potential marker of poor prognosis in HER2 positive BC. Further studies are needed to elucidate how VMP1 could affect pathways supportive of tumorigenesis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0221413PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6707546PMC
March 2020

Genome-wide association and transcriptome studies identify target genes and risk loci for breast cancer.

Nat Commun 2019 04 15;10(1):1741. Epub 2019 Apr 15.

Molecular Oncology Laboratory, CIBERONC, Hospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), 28040, Madrid, Spain.

Genome-wide association studies (GWAS) have identified more than 170 breast cancer susceptibility loci. Here we hypothesize that some risk-associated variants might act in non-breast tissues, specifically adipose tissue and immune cells from blood and spleen. Using expression quantitative trait loci (eQTL) reported in these tissues, we identify 26 previously unreported, likely target genes of overall breast cancer risk variants, and 17 for estrogen receptor (ER)-negative breast cancer, several with a known immune function. We determine the directional effect of gene expression on disease risk measured based on single and multiple eQTL. In addition, using a gene-based test of association that considers eQTL from multiple tissues, we identify seven (and four) regions with variants associated with overall (and ER-negative) breast cancer risk, which were not reported in previous GWAS. Further investigation of the function of the implicated genes in breast and immune cells may provide insights into the etiology of breast cancer.
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http://dx.doi.org/10.1038/s41467-018-08053-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6465407PMC
April 2019

Mutational spectrum in a worldwide study of 29,700 families with BRCA1 or BRCA2 mutations.

Hum Mutat 2018 05 12;39(5):593-620. Epub 2018 Mar 12.

Lunenfeld-Tanenbaum Research Institute, Toronto, Canada.

The prevalence and spectrum of germline mutations in BRCA1 and BRCA2 have been reported in single populations, with the majority of reports focused on White in Europe and North America. The Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA) has assembled data on 18,435 families with BRCA1 mutations and 11,351 families with BRCA2 mutations ascertained from 69 centers in 49 countries on six continents. This study comprehensively describes the characteristics of the 1,650 unique BRCA1 and 1,731 unique BRCA2 deleterious (disease-associated) mutations identified in the CIMBA database. We observed substantial variation in mutation type and frequency by geographical region and race/ethnicity. In addition to known founder mutations, mutations of relatively high frequency were identified in specific racial/ethnic or geographic groups that may reflect founder mutations and which could be used in targeted (panel) first pass genotyping for specific populations. Knowledge of the population-specific mutational spectrum in BRCA1 and BRCA2 could inform efficient strategies for genetic testing and may justify a more broad-based oncogenetic testing in some populations.
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http://dx.doi.org/10.1002/humu.23406DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5903938PMC
May 2018

Prediction of Breast and Prostate Cancer Risks in Male BRCA1 and BRCA2 Mutation Carriers Using Polygenic Risk Scores.

J Clin Oncol 2017 Jul 27;35(20):2240-2250. Epub 2017 Apr 27.

Julie Lecarpentier, Karoline B. Kuchenbaecker, Daniel Barrowdale, Joe Dennis, Lesley McGuffog, Goska Leslie, Andrew Lee, Ali Amin Al Olama, Jonathan P. Tyrer, Debra Frost, Steve Ellis, Douglas F. Easton, and Antonis C. Antoniou, University of Cambridge; Karoline B. Kuchenbaecker, The Wellcome Trust Sanger Institute, Hinxton; Marc Tischkowitz, Addenbrooke's Treatment Centre, Addenbrooke's Hospital, Cambridge; D. Gareth Evans, Manchester University, Central Manchester University Hospitals NHS Foundation Trust, Manchester; Alex Henderson, Newcastle Upon Tyne Hospitals NHS Trust, Newcastle upon Tyne; Carole Brewer, Royal Devon and Exeter Hospital, Exeter; Diana Eccles, Southampton University Hospitals NHS Trust, Southampton; Jackie Cook, Sheffield Children's Hospital, Sheffield; Kai-ren Ong, Birmingham Women's Hospital Healthcare NHS Trust, Edgbaston, Birmingham; Lisa Walker, Churchill Hospital, Oxford; Lucy E. Side, Great Ormond Street Hospital for Children NHS Trust; Shirley Hodgson, St George's, University of London; Louise Izatt, Guy's and St Thomas' NHS Foundation Trust; Ros Eeles, The Institute of Cancer Research and Royal Marsden NHS Foundation Trust; Nick Orr, The Institute of Cancer Research, London; Mary E. Porteous, Western General Hospital, Edinburgh; Rosemarie Davidson, South Glasgow University Hospitals, Glasgow; Julian Adlard, Chapel Allerton Hospital, Leeds, United Kingdom; Valentina Silvestri, Piera Rizzolo, Anna Sara Navazio, Virginia Valentini, Veronica Zelli, and Laura Ottini, Sapienza University of Rome, Rome; Angela Toss, Veronica Medici, and Laura Cortesi, University of Modena and Reggio Emilia, Modena; Ines Zanna and Domenico Palli, Cancer Research and Prevention Institute, Florence; Paolo Radice, Siranoush Manoukian, Bernard Peissel, and Jacopo Azzollini, Fondazione Istituto Di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Nazionale Tumori (INT); Paolo Peterlongo, Italian Foundation for Cancer Research Institute of Molecular Oncology (IFOM), Milan; Alessandra Viel and Giulia Cini, CRO Aviano, National Cancer Institute, Aviano; Giuseppe Damante, University of Udine, Udine; Stefania Tommasi, Istituto Nazionale Tumori "Giovanni Paolo II", Bari; Elisa Alducci, Silvia Tognazzo, and Marco Montagna, Veneto Institute of Oncology IOV - IRCCS, Padua; Maria A. Caligo, University and University Hospital of Pisa, Pisa, Italy; Penny Soucy and Jacques Simard, Centre Hospitalier Universitaire de Québec Research Center and Laval University, Quebec City, Quebec; Anna Marie Mulligan and Irene L. Andrulis, University of Toronto; Gord Glendon and Irene L. Andrulis, Mount Sinai Hospital, Toronto, Ontario, Canada; Melissa Southey, Ian Campbell, Paul James, and Gillian Mitchell, University of Melbourne, Parkville, Victoria; Amanda B. Spurdle, Helene Holland, and Georgia Chenevix-Trench, QIMR Berghofer Medical Research Institute, Brisbane, Queensland; Ian Campbell, Paul James, and Gillian Mitchell, Peter MacCallum Cancer Centre, East Melbourne, New South Wales, Australia; Esther M. John, Cancer Prevention Institute of California, Fremont; Linda Steele, Yuan Chun Ding, Susan L. Neuhausen, and Jeffrey N. Weitzel, City of Hope, Duarte, CA; Thomas A. Conner and Saundra S. Buys, Huntsman Cancer Institute; David E. Goldgar, University of Utah School of Medicine, Salt Lake City, UT; Andrew K. Godwin, University of Kansas Medical Center, Kansas City; Priyanka Sharma, University of Kansas Medical Center, Westwood, KS; Timothy R. Rebbeck, Harvard TH Chan School of Public Health and Dana Farber Cancer Institute, Boston, MA; Joseph Vijai, Mark Robson, Anne Lincoln, Jacob Musinsky, Pragna Gaddam, and Kenneth Offit, Memorial Sloan Kettering Cancer Center, New York, NY; Jennifer T. Loud and Mark H. Greene, National Cancer Institute, Bethesda, MD; Amanda Ewart Toland and Leigha Senter, The Ohio State University, Columbus, OH; Dezheng Huo, Sarah M. Nielsen, and Olufunmilayo I. Olopade, University of Chicago Medical Center, Chicago, IL; Katherine L. Nathanson and Susan M. Domchek, University of Pennsylvania, Philadelphia; Christa Lorenchick and Rachel C. Jankowitz, University of Pittsburgh Medical Center, Pittsburgh, PA; Fergus J. Couch, Mayo Clinic, Rochester, MN; Ramunas Janavicius, State Research Institute Innovative Medicine Center, Vilnius, Lithuania; Thomas V.O. Hansen, Rigshospitalet, Copenhagen University Hospital, Copenhagen; Anders Bojesen and Henriette Roed Nielsen, Vejle Hospital, Vejle; Anne-Bine Skytte, Lone Sunde, and Uffe Birk Jensen, Aarhus University Hospital, Aarhus; Inge Sokilde Pedersen, Aalborg University Hospital, Aalborg; Lotte Krogh, Torben A. Kruse, and Mads Thomassen, Odense University Hospital, Odense, Denmark; Ana Osorio, National Cancer Research Centre and Spanish Network on Rare Diseases; Miguel de la Hoya, Vanesa Garcia-Barberan, Trinidad Caldes, and Pedro Perez Segura, Hospital Clinico San Carlos, El Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid; Judith Balmaña, University Hospital, Vall d'Hebron; Sara Gutiérrez-Enríquez and Orland Diez, Vall d'Hebron Institute of Oncology; Orland Diez, University Hospital Vall d'Hebron; Alex Teulé, Jesús Del Valle, Lidia Feliubadalo, Miquel Angel Pujana, and Conxi Lazaro, Bellvitge Biomedical Research Institute, Catalan Institute of Oncology, Barcelona; Angel Izquierdo, Esther Darder, and Joan Brunet, Institut d'Investigació Biomèdica de Girona, Catalan Institute of Oncology, Girona, Spain; Florentia Fostira, National Centre for Scientific Research "Demokritos," Athens, Greece; Ute Hamann, German Cancer Research Center (DKFZ); Christian Sutter, University Hospital Heidelberg, Heidelberg; Alfons Meindl, Klinikumrechts der Isar, Technical University Munich; Nina Ditsch, Ludwig-Maximilian University, Munich; Andrea Gehrig, University Würzburg, Würzburg; Bernd Dworniczak, University of Münster, Münster; Christoph Engel, University of Leipzig; Dorothea Wand, University Hospital, Leipzig; Dieter Niederacher, University Hospital Düsseldorf, Heinrich-Heine University, Düsseldorf; Doris Steinemann, Hannover Medical School, Hannover; Eric Hahnen, Jan Hauke, Kerstin Rhiem, Barbara Wappenschmidt, and Rita K. Schmutzler, University Hospital Cologne, Cologne; Karin Kast, University Hospital Carl Gustav Carus, Technical University Dresden, Dresden; Norbert Arnold, University Hospital of Schleswig-Holstein, Christian-Albrechts University Kiel, Kiel; Shan Wang-Gohrke, University Hospital Ulm, Ulm, Germany; Christine Lasset, Francesca Damiola, and Laure Barjhoux, Centre Léon Bérard; Sylvie Mazoyer, University of Lyon, Lyon; Dominique Stoppa-Lyonnet and Muriel Belotti, Institut Curie, Paris, France; Mattias Van Heetvelde, Bruce Poppe, Kim De Leeneer, and Kathleen B.M. Claes, Ghent University, Gent, Belgium; Johanna I. Kiiski, Sofia Khan, and Heli Nevanlinna, University of Helsinki; Johanna I. Kiiski, Kristiina Aittomäki, Sofia Khan, and Heli Nevanlinna, Helsinki University Hospital, Helsinki, Finland; Christi J. van Asperen, Leiden University Medical Center, Leiden, the Netherlands; Tibor Vaszko, Miklos Kasler, and Edith Olah, National Institute of Oncology, Budapest, Hungary; Adalgeir Arason, Bjarni A. Agnarsson, Oskar Th. Johannsson, and Rosa B. Barkardottir, Landspitali University Hospital and Biomedical Centre, University of Iceland, Reykjavik, Iceland; Manuel R. Teixeira and Pedro Pinto, Portuguese Oncology Institute; Manuel R. Teixeira, Porto University, Porto, Portugal; Jong Won Lee, Ulsan College of Medicine and Asan Medical Center; Min Hyuk Lee and Jihyoun Lee, Soonchunhyang University and Hospital; Sung-Won Kim and Eunyoung Kang, Daerim St Mary's Hospital; Sue Kyung Park, Seoul National University College of Medicine, Seoul; Zisun Kim, Soonchunhyang University Bucheon Hospital, Bucheon, Korea; Yen Y. Tan, Andreas Berger, and Christian F. Singer, Medical University of Vienna, Vienna, Austria; Sook-Yee Yoon and Soo-Hwang Teo, Sime Darby Medical Centre, Subang Jaya, Malaysia; and Anna von Wachenfeldt, Karolinska University Hospital, Stockholm, Sweden.

Purpose BRCA1/2 mutations increase the risk of breast and prostate cancer in men. Common genetic variants modify cancer risks for female carriers of BRCA1/2 mutations. We investigated-for the first time to our knowledge-associations of common genetic variants with breast and prostate cancer risks for male carriers of BRCA1/ 2 mutations and implications for cancer risk prediction. Materials and Methods We genotyped 1,802 male carriers of BRCA1/2 mutations from the Consortium of Investigators of Modifiers of BRCA1/2 by using the custom Illumina OncoArray. We investigated the combined effects of established breast and prostate cancer susceptibility variants on cancer risks for male carriers of BRCA1/2 mutations by constructing weighted polygenic risk scores (PRSs) using published effect estimates as weights. Results In male carriers of BRCA1/2 mutations, PRS that was based on 88 female breast cancer susceptibility variants was associated with breast cancer risk (odds ratio per standard deviation of PRS, 1.36; 95% CI, 1.19 to 1.56; P = 8.6 × 10). Similarly, PRS that was based on 103 prostate cancer susceptibility variants was associated with prostate cancer risk (odds ratio per SD of PRS, 1.56; 95% CI, 1.35 to 1.81; P = 3.2 × 10). Large differences in absolute cancer risks were observed at the extremes of the PRS distribution. For example, prostate cancer risk by age 80 years at the 5th and 95th percentiles of the PRS varies from 7% to 26% for carriers of BRCA1 mutations and from 19% to 61% for carriers of BRCA2 mutations, respectively. Conclusion PRSs may provide informative cancer risk stratification for male carriers of BRCA1/2 mutations that might enable these men and their physicians to make informed decisions on the type and timing of breast and prostate cancer risk management.
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http://dx.doi.org/10.1200/JCO.2016.69.4935DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5501359PMC
July 2017

Association of breast cancer risk in BRCA1 and BRCA2 mutation carriers with genetic variants showing differential allelic expression: identification of a modifier of breast cancer risk at locus 11q22.3.

Breast Cancer Res Treat 2017 01 28;161(1):117-134. Epub 2016 Oct 28.

Center for Medical Genetics, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium.

Purpose: Cis-acting regulatory SNPs resulting in differential allelic expression (DAE) may, in part, explain the underlying phenotypic variation associated with many complex diseases. To investigate whether common variants associated with DAE were involved in breast cancer susceptibility among BRCA1 and BRCA2 mutation carriers, a list of 175 genes was developed based of their involvement in cancer-related pathways.

Methods: Using data from a genome-wide map of SNPs associated with allelic expression, we assessed the association of ~320 SNPs located in the vicinity of these genes with breast and ovarian cancer risks in 15,252 BRCA1 and 8211 BRCA2 mutation carriers ascertained from 54 studies participating in the Consortium of Investigators of Modifiers of BRCA1/2.

Results: We identified a region on 11q22.3 that is significantly associated with breast cancer risk in BRCA1 mutation carriers (most significant SNP rs228595 p = 7 × 10). This association was absent in BRCA2 carriers (p = 0.57). The 11q22.3 region notably encompasses genes such as ACAT1, NPAT, and ATM. Expression quantitative trait loci associations were observed in both normal breast and tumors across this region, namely for ACAT1, ATM, and other genes. In silico analysis revealed some overlap between top risk-associated SNPs and relevant biological features in mammary cell data, which suggests potential functional significance.

Conclusion: We identified 11q22.3 as a new modifier locus in BRCA1 carriers. Replication in larger studies using estrogen receptor (ER)-negative or triple-negative (i.e., ER-, progesterone receptor-, and HER2-negative) cases could therefore be helpful to confirm the association of this locus with breast cancer risk.
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http://dx.doi.org/10.1007/s10549-016-4018-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5222911PMC
January 2017

Oestrogen receptor status, treatment and breast cancer prognosis in Icelandic BRCA2 mutation carriers.

Br J Cancer 2016 09 18;115(7):776-83. Epub 2016 Aug 18.

Icelandic Cancer Registry, Icelandic Cancer Society, Reykjavik, Iceland.

Background: The impact of an inherited BRCA2 mutation on the prognosis of women with breast cancer has not been well documented. We studied the effects of oestrogen receptor (ER) status, other prognostic factors and treatments on survival in a large cohort of BRCA2 mutation carriers.

Methods: We identified 285 breast cancer patients with a 999del5 BRCA2 mutation and matched them with 570 non-carrier patients. Clinical information was abstracted from patient charts and pathology records and supplemented by evaluation of tumour grade and ER status using archived tissue specimens. Univariate and multivariate hazard ratios (HR) were estimated for breast cancer-specific survival using Cox regression. The effects of various therapies were studied in patients treated from 1980 to 2012.

Results: Among mutation carriers, positive ER status was associated with higher risk of death than negative ER status (HR=1.94; 95% CI=1.22-3.07, P=0.005). The reverse association was seen for non-carriers (HR=0.71; 95% CI: 0.51-0.97; P=0.03).

Conclusions: Among BRCA2 carriers, ER-positive status is an adverse prognostic factor. BRCA2 carrier status should be known at the time when treatment decisions are made.
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http://dx.doi.org/10.1038/bjc.2016.249DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5046206PMC
September 2016

Identification of independent association signals and putative functional variants for breast cancer risk through fine-scale mapping of the 12p11 locus.

Breast Cancer Res 2016 06 21;18(1):64. Epub 2016 Jun 21.

Institute of Biochemistry and Genetics, Ufa Scientific Center of Russian Academy of Sciences, Ufa, Russia.

Background: Multiple recent genome-wide association studies (GWAS) have identified a single nucleotide polymorphism (SNP), rs10771399, at 12p11 that is associated with breast cancer risk.

Method: We performed a fine-scale mapping study of a 700 kb region including 441 genotyped and more than 1300 imputed genetic variants in 48,155 cases and 43,612 controls of European descent, 6269 cases and 6624 controls of East Asian descent and 1116 cases and 932 controls of African descent in the Breast Cancer Association Consortium (BCAC; http://bcac.ccge.medschl.cam.ac.uk/ ), and in 15,252 BRCA1 mutation carriers in the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA). Stepwise regression analyses were performed to identify independent association signals. Data from the Encyclopedia of DNA Elements project (ENCODE) and the Cancer Genome Atlas (TCGA) were used for functional annotation.

Results: Analysis of data from European descendants found evidence for four independent association signals at 12p11, represented by rs7297051 (odds ratio (OR) = 1.09, 95 % confidence interval (CI) = 1.06-1.12; P = 3 × 10(-9)), rs805510 (OR = 1.08, 95 % CI = 1.04-1.12, P = 2 × 10(-5)), and rs1871152 (OR = 1.04, 95 % CI = 1.02-1.06; P = 2 × 10(-4)) identified in the general populations, and rs113824616 (P = 7 × 10(-5)) identified in the meta-analysis of BCAC ER-negative cases and BRCA1 mutation carriers. SNPs rs7297051, rs805510 and rs113824616 were also associated with breast cancer risk at P < 0.05 in East Asians, but none of the associations were statistically significant in African descendants. Multiple candidate functional variants are located in putative enhancer sequences. Chromatin interaction data suggested that PTHLH was the likely target gene of these enhancers. Of the six variants with the strongest evidence of potential functionality, rs11049453 was statistically significantly associated with the expression of PTHLH and its nearby gene CCDC91 at P < 0.05.

Conclusion: This study identified four independent association signals at 12p11 and revealed potentially functional variants, providing additional insights into the underlying biological mechanism(s) for the association observed between variants at 12p11 and breast cancer risk.
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http://dx.doi.org/10.1186/s13058-016-0718-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4962376PMC
June 2016

Male breast cancer in BRCA1 and BRCA2 mutation carriers: pathology data from the Consortium of Investigators of Modifiers of BRCA1/2.

Breast Cancer Res 2016 Feb 9;18(1):15. Epub 2016 Feb 9.

Center for Medical Genetics, North Shore University Health System, Evanston, IL, USA.

Background: BRCA1 and, more commonly, BRCA2 mutations are associated with increased risk of male breast cancer (MBC). However, only a paucity of data exists on the pathology of breast cancers (BCs) in men with BRCA1/2 mutations. Using the largest available dataset, we determined whether MBCs arising in BRCA1/2 mutation carriers display specific pathologic features and whether these features differ from those of BRCA1/2 female BCs (FBCs).

Methods: We characterised the pathologic features of 419 BRCA1/2 MBCs and, using logistic regression analysis, contrasted those with data from 9675 BRCA1/2 FBCs and with population-based data from 6351 MBCs in the Surveillance, Epidemiology, and End Results (SEER) database.

Results: Among BRCA2 MBCs, grade significantly decreased with increasing age at diagnosis (P = 0.005). Compared with BRCA2 FBCs, BRCA2 MBCs were of significantly higher stage (P for trend = 2 × 10(-5)) and higher grade (P for trend = 0.005) and were more likely to be oestrogen receptor-positive [odds ratio (OR) 10.59; 95 % confidence interval (CI) 5.15-21.80] and progesterone receptor-positive (OR 5.04; 95 % CI 3.17-8.04). With the exception of grade, similar patterns of associations emerged when we compared BRCA1 MBCs and FBCs. BRCA2 MBCs also presented with higher grade than MBCs from the SEER database (P for trend = 4 × 10(-12)).

Conclusions: On the basis of the largest series analysed to date, our results show that BRCA1/2 MBCs display distinct pathologic characteristics compared with BRCA1/2 FBCs, and we identified a specific BRCA2-associated MBC phenotype characterised by a variable suggesting greater biological aggressiveness (i.e., high histologic grade). These findings could lead to the development of gender-specific risk prediction models and guide clinical strategies appropriate for MBC management.
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http://dx.doi.org/10.1186/s13058-016-0671-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4746828PMC
February 2016

Association of type and location of BRCA1 and BRCA2 mutations with risk of breast and ovarian cancer.

JAMA 2015 Apr;313(13):1347-61

Department of Medicine and Genetics, University of California, San Francisco.

Importance: Limited information about the relationship between specific mutations in BRCA1 or BRCA2 (BRCA1/2) and cancer risk exists.

Objective: To identify mutation-specific cancer risks for carriers of BRCA1/2.

Design, Setting, And Participants: Observational study of women who were ascertained between 1937 and 2011 (median, 1999) and found to carry disease-associated BRCA1 or BRCA2 mutations. The international sample comprised 19,581 carriers of BRCA1 mutations and 11,900 carriers of BRCA2 mutations from 55 centers in 33 countries on 6 continents. We estimated hazard ratios for breast and ovarian cancer based on mutation type, function, and nucleotide position. We also estimated RHR, the ratio of breast vs ovarian cancer hazard ratios. A value of RHR greater than 1 indicated elevated breast cancer risk; a value of RHR less than 1 indicated elevated ovarian cancer risk.

Exposures: Mutations of BRCA1 or BRCA2.

Main Outcomes And Measures: Breast and ovarian cancer risks.

Results: Among BRCA1 mutation carriers, 9052 women (46%) were diagnosed with breast cancer, 2317 (12%) with ovarian cancer, 1041 (5%) with breast and ovarian cancer, and 7171 (37%) without cancer. Among BRCA2 mutation carriers, 6180 women (52%) were diagnosed with breast cancer, 682 (6%) with ovarian cancer, 272 (2%) with breast and ovarian cancer, and 4766 (40%) without cancer. In BRCA1, we identified 3 breast cancer cluster regions (BCCRs) located at c.179 to c.505 (BCCR1; RHR = 1.46; 95% CI, 1.22-1.74; P = 2 × 10(-6)), c.4328 to c.4945 (BCCR2; RHR = 1.34; 95% CI, 1.01-1.78; P = .04), and c. 5261 to c.5563 (BCCR2', RHR = 1.38; 95% CI, 1.22-1.55; P = 6 × 10(-9)). We also identified an ovarian cancer cluster region (OCCR) from c.1380 to c.4062 (approximately exon 11) with RHR = 0.62 (95% CI, 0.56-0.70; P = 9 × 10(-17)). In BRCA2, we observed multiple BCCRs spanning c.1 to c.596 (BCCR1; RHR = 1.71; 95% CI, 1.06-2.78; P = .03), c.772 to c.1806 (BCCR1'; RHR = 1.63; 95% CI, 1.10-2.40; P = .01), and c.7394 to c.8904 (BCCR2; RHR = 2.31; 95% CI, 1.69-3.16; P = .00002). We also identified 3 OCCRs: the first (OCCR1) spanned c.3249 to c.5681 that was adjacent to c.5946delT (6174delT; RHR = 0.51; 95% CI, 0.44-0.60; P = 6 × 10(-17)). The second OCCR spanned c.6645 to c.7471 (OCCR2; RHR = 0.57; 95% CI, 0.41-0.80; P = .001). Mutations conferring nonsense-mediated decay were associated with differential breast or ovarian cancer risks and an earlier age of breast cancer diagnosis for both BRCA1 and BRCA2 mutation carriers.

Conclusions And Relevance: Breast and ovarian cancer risks varied by type and location of BRCA1/2 mutations. With appropriate validation, these data may have implications for risk assessment and cancer prevention decision making for carriers of BRCA1 and BRCA2 mutations.
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http://dx.doi.org/10.1001/jama.2014.5985DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4537700PMC
April 2015

Candidate genetic modifiers for breast and ovarian cancer risk in BRCA1 and BRCA2 mutation carriers.

Cancer Epidemiol Biomarkers Prev 2015 Jan 21;24(1):308-16. Epub 2014 Oct 21.

University of Texas MD Anderson Cancer Center, Houston, Texas.

Background: BRCA1 and BRCA2 mutation carriers are at substantially increased risk for developing breast and ovarian cancer. The incomplete penetrance coupled with the variable age at diagnosis in carriers of the same mutation suggests the existence of genetic and nongenetic modifying factors. In this study, we evaluated the putative role of variants in many candidate modifier genes.

Methods: Genotyping data from 15,252 BRCA1 and 8,211 BRCA2 mutation carriers, for known variants (n = 3,248) located within or around 445 candidate genes, were available through the iCOGS custom-designed array. Breast and ovarian cancer association analysis was performed within a retrospective cohort approach.

Results: The observed P values of association ranged between 0.005 and 1.000. None of the variants was significantly associated with breast or ovarian cancer risk in either BRCA1 or BRCA2 mutation carriers, after multiple testing adjustments.

Conclusion: There is little evidence that any of the evaluated candidate variants act as modifiers of breast and/or ovarian cancer risk in BRCA1 or BRCA2 mutation carriers.

Impact: Genome-wide association studies have been more successful at identifying genetic modifiers of BRCA1/2 penetrance than candidate gene studies.
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http://dx.doi.org/10.1158/1055-9965.EPI-14-0532DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4294951PMC
January 2015

Associations of common breast cancer susceptibility alleles with risk of breast cancer subtypes in BRCA1 and BRCA2 mutation carriers.

Breast Cancer Res 2014 Dec 31;16(6):3416. Epub 2014 Dec 31.

Introduction: More than 70 common alleles are known to be involved in breast cancer (BC) susceptibility, and several exhibit significant heterogeneity in their associations with different BC subtypes. Although there are differences in the association patterns between BRCA1 and BRCA2 mutation carriers and the general population for several loci, no study has comprehensively evaluated the associations of all known BC susceptibility alleles with risk of BC subtypes in BRCA1 and BRCA2 carriers.

Methods: We used data from 15,252 BRCA1 and 8,211 BRCA2 carriers to analyze the associations between approximately 200,000 genetic variants on the iCOGS array and risk of BC subtypes defined by estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) and triple-negative- (TN) status; morphologic subtypes; histological grade; and nodal involvement.

Results: The estimated BC hazard ratios (HRs) for the 74 known BC alleles in BRCA1 carriers exhibited moderate correlations with the corresponding odds ratios from the general population. However, their associations with ER-positive BC in BRCA1 carriers were more consistent with the ER-positive associations in the general population (intraclass correlation (ICC) = 0.61, 95% confidence interval (CI): 0.45 to 0.74), and the same was true when considering ER-negative associations in both groups (ICC = 0.59, 95% CI: 0.42 to 0.72). Similarly, there was strong correlation between the ER-positive associations for BRCA1 and BRCA2 carriers (ICC = 0.67, 95% CI: 0.52 to 0.78), whereas ER-positive associations in any one of the groups were generally inconsistent with ER-negative associations in any of the others. After stratifying by ER status in mutation carriers, additional significant associations were observed. Several previously unreported variants exhibited associations at P <10(-6) in the analyses by PR status, HER2 status, TN phenotype, morphologic subtypes, histological grade and nodal involvement.

Conclusions: Differences in associations of common BC susceptibility alleles between BRCA1 and BRCA2 carriers and the general population are explained to a large extent by differences in the prevalence of ER-positive and ER-negative tumors. Estimates of the risks associated with these variants based on population-based studies are likely to be applicable to mutation carriers after taking ER status into account, which has implications for risk prediction.
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http://dx.doi.org/10.1186/s13058-014-0492-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4406179PMC
December 2014

High expression of ZNF703 independent of amplification indicates worse prognosis in patients with luminal B breast cancer.

Cancer Med 2013 Aug 22;2(4):437-46. Epub 2013 May 22.

Department of Pathology, Landspitali-University Hospital 101, Reykjavik, Iceland.

Amplification of 8p12-p11 is relatively common in breast cancer and several genes within the region have been suggested to affect breast tumor progression. The aim of the study was to map the amplified 8p12-p11 region in a large set of breast tumors in an effort to identify the genetic driver and to explore its impact on tumor progression and prognosis. Copy number alterations (CNAs) were mapped in 359 tumors, and gene expression data from 577 tumors (359 tumors included) were correlated with CNA, clinical-pathological factors, and protein expression (39 tumors). 8p12-p11 was amplified in 11.4% of tumors. The smallest region of amplification harbored one full-length gene, ZNF703. ZNF703 mRNA expression was significantly higher in estrogen receptor (ER)-positive than ER-negative tumors (P = 2 × 10(-16)), a reflection of high expression in luminal tumors. Forty-eight percent of tumors with ZNF703 amplification were luminal B tumors in which the best correlation between DNA copy number and mRNA was seen (P = 1.2 × 10(-7)) as well as correlation between mRNA and protein expression (P = 0.02). High ZNF703 mRNA correlated with poor survival in patients with ER-positive luminal B tumors (log rank P = 0.04). Furthermore, high ZNF703 mRNA expression correlated with poor outcome in patients with ZNF703 copy number neutral, ER-positive, luminal B tumors (log rank P = 0.004). The results support ZNF703 as the driver gene of the 8p12 amplification and suggest that independent of amplification, high expression of the gene affects prognosis in luminal B tumors.
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http://dx.doi.org/10.1002/cam4.88DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3799278PMC
August 2013

Identification of a BRCA2-specific modifier locus at 6p24 related to breast cancer risk.

PLoS Genet 2013 27;9(3):e1003173. Epub 2013 Mar 27.

Epidemiology Research Program, American Cancer Society, Atlanta, Georgia, USA.

Common genetic variants contribute to the observed variation in breast cancer risk for BRCA2 mutation carriers; those known to date have all been found through population-based genome-wide association studies (GWAS). To comprehensively identify breast cancer risk modifying loci for BRCA2 mutation carriers, we conducted a deep replication of an ongoing GWAS discovery study. Using the ranked P-values of the breast cancer associations with the imputed genotype of 1.4 M SNPs, 19,029 SNPs were selected and designed for inclusion on a custom Illumina array that included a total of 211,155 SNPs as part of a multi-consortial project. DNA samples from 3,881 breast cancer affected and 4,330 unaffected BRCA2 mutation carriers from 47 studies belonging to the Consortium of Investigators of Modifiers of BRCA1/2 were genotyped and available for analysis. We replicated previously reported breast cancer susceptibility alleles in these BRCA2 mutation carriers and for several regions (including FGFR2, MAP3K1, CDKN2A/B, and PTHLH) identified SNPs that have stronger evidence of association than those previously published. We also identified a novel susceptibility allele at 6p24 that was inversely associated with risk in BRCA2 mutation carriers (rs9348512; per allele HR = 0.85, 95% CI 0.80-0.90, P = 3.9 × 10(-8)). This SNP was not associated with breast cancer risk either in the general population or in BRCA1 mutation carriers. The locus lies within a region containing TFAP2A, which encodes a transcriptional activation protein that interacts with several tumor suppressor genes. This report identifies the first breast cancer risk locus specific to a BRCA2 mutation background. This comprehensive update of novel and previously reported breast cancer susceptibility loci contributes to the establishment of a panel of SNPs that modify breast cancer risk in BRCA2 mutation carriers. This panel may have clinical utility for women with BRCA2 mutations weighing options for medical prevention of breast cancer.
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http://dx.doi.org/10.1371/journal.pgen.1003173DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3609647PMC
June 2013

The risk allele of SNP rs3803662 and the mRNA level of its closest genes TOX3 and LOC643714 predict adverse outcome for breast cancer patients.

BMC Cancer 2012 Dec 27;12:621. Epub 2012 Dec 27.

Department of Pathology, Landspitali-University Hospital, Hringbraut, 101, Reykjavik, Iceland.

Background: The minor allele of SNP rs3803662 has been shown to correlate with increased breast cancer risk and with lower expression of TOX3. The SNP is closely located to TOX3 residing within an uncharacterised gene LOC643714. The aim of the study was to examine the association of the risk allele with expression of TOX3 and LOC643714, and of mRNA levels and genotype with clinical and pathological characteristics.

Methods: The SNP was genotyped in DNA isolated from blood and normal tissue from 160 breast cancer patients and mRNA levels were measured by microarrays and quantitative real-time (qRT)-PCR in breast tumours. Association with clinical and pathological characteristics was analysed by parametric tests.

Results: An association of the risk allele of rs3803662 with lower TOX3 expression was confirmed in oestrogen receptor (ER) positive tumours. It was more often observed in lobular tumours (p = 0.04), and carriers of the risk allele who had been diagnosed with luminal A tumours had shorter overall survival (OS) than carriers of the non-risk allele (p = 0.01). Positive correlation between the mRNA levels of TOX3 and LOC643714 was observed (r = 0.44 and p < 0.001). Association analysis with tumour pathology showed that low TOX3 and LOC643714 expression correlated with high Ki67 levels (p = 0.026 and p = 0.002) and the basal subtype (p < 0.001 and p < 0.001), whereas high expression correlated with ER (p = 0.004 and p < 0.001) and progesterone receptor (PgR) (p = 0.005 and p < 0.001) expression. Furthermore, high TOX3 and LOC643714 correlated with positive lymph nodes (p < 0.001 and p = 0.01). Patients with ER positive tumours and high levels of TOX3 mRNA had shorter overall- and distant metastasis free-survival (p = 0.017 and p = 0.021), an effect mostly attributable to patients with luminal B tumours.

Conclusions: The results suggest that the effect of the risk allele of rs3803662 is strongest in luminal A tumours and that the expression levels of TOX3 and/or LOC643714 affect the progression of breast cancer. The effect may vary depending on the subtype and developmental stage of the tumour.
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http://dx.doi.org/10.1186/1471-2407-12-621DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3553017PMC
December 2012

Evaluation of chromosome 6p22 as a breast cancer risk modifier locus in a follow-up study of BRCA2 mutation carriers.

Breast Cancer Res Treat 2012 Nov 26;136(1):295-302. Epub 2012 Sep 26.

Department of Health Sciences Research, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.

Several common germline variants identified through genome-wide association studies of breast cancer risk in the general population have recently been shown to be associated with breast cancer risk for BRCA1 and/or BRCA2 mutation carriers. When combined, these variants can identify marked differences in the absolute risk of developing breast cancer for mutation carriers, suggesting that additional modifier loci may further enhance individual risk assessment for BRCA1 and BRCA2 mutation carriers. Recently, a common variant on 6p22 (rs9393597) was found to be associated with increased breast cancer risk for BRCA2 mutation carriers [hazard ratio (HR) = 1.55, 95 % confidence interval (CI) 1.25-1.92, p = 6.0 × 10(-5)]. This observation was based on data from GWAS studies in which, despite statistical correction for multiple comparisons, the possibility of false discovery remains a concern. Here, we report on an analysis of this variant in an additional 6,165 BRCA1 and 3,900 BRCA2 mutation carriers from the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA). In this replication analysis, rs9393597 was not associated with breast cancer risk for BRCA2 mutation carriers (HR = 1.09, 95 % CI 0.96-1.24, p = 0.18). No association with ovarian cancer risk for BRCA1 or BRCA2 mutation carriers or with breast cancer risk for BRCA1 mutation carriers was observed. This follow-up study suggests that, contrary to our initial report, this variant is not associated with breast cancer risk among individuals with germline BRCA2 mutations.
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http://dx.doi.org/10.1007/s10549-012-2255-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3482828PMC
November 2012

The retinoblastoma gene undergoes rearrangements in BRCA1-deficient basal-like breast cancer.

Cancer Res 2012 Aug 15;72(16):4028-36. Epub 2012 Jun 15.

Department of Oncology, CREATE Health Strategic Center for Translational Cancer Research, Lund University, Skåne Department of Oncology, Skåne University Hospital, Lund, Sweden.

Breast tumors from BRCA1 germ line mutation carriers typically exhibit features of the basal-like molecular subtype. However, the specific genes recurrently mutated as a consequence of BRCA1 dysfunction have not been fully elucidated. In this study, we used gene expression profiling to molecularly subtype 577 breast tumors, including 73 breast tumors from BRCA1/2 mutation carriers. Focusing on the RB1 locus, we analyzed 33 BRCA1-mutated, 36 BRCA2-mutated, and 48 non-BRCA1/2-mutated breast tumors using a custom-designed high-density oligomicroarray covering the RB1 gene. We found a strong association between the basal-like subtype and BRCA1-mutated breast tumors and the luminal B subtype and BRCA2-mutated breast tumors. RB1 was identified as a major target for genomic disruption in tumors arising in BRCA1 mutation carriers and in sporadic tumors with BRCA1 promoter methylation but rarely in other breast cancers. Homozygous deletions, intragenic breaks, or microdeletions were found in 33% of BRCA1-mutant tumors, 36% of BRCA1 promoter-methylated basal-like tumors, 13% of non-BRCA1-deficient basal-like tumors, and 3% of BRCA2-mutated tumors. In conclusion, RB1 was frequently inactivated by gross gene disruption in BRCA1 hereditary breast cancer and BRCA1-methylated sporadic basal-like breast cancer but rarely in BRCA2 hereditary breast cancer and non-BRCA1-deficient sporadic breast cancers. Together, our findings show the existence of genetic heterogeneity within the basal-like breast cancer subtype that is based upon BRCA1 status.
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http://dx.doi.org/10.1158/0008-5472.CAN-12-0097DOI Listing
August 2012

The KL-VS sequence variant of Klotho and cancer risk in BRCA1 and BRCA2 mutation carriers.

Breast Cancer Res Treat 2012 Apr 3;132(3):1119-26. Epub 2012 Jan 3.

The Susanne Levy Gertner Oncogenetics Unit 1, The Danek Gertner Institute of Human Genetics, Chaim Sheba Medical Center, Tel-Hashomer 52621, Israel.

Klotho (KL) is a putative tumor suppressor gene in breast and pancreatic cancers located at chromosome 13q12. A functional sequence variant of Klotho (KL-VS) was previously reported to modify breast cancer risk in Jewish BRCA1 mutation carriers. The effect of this variant on breast and ovarian cancer risks in non-Jewish BRCA1/BRCA2 mutation carriers has not been reported. The KL-VS variant was genotyped in women of European ancestry carrying a BRCA mutation: 5,741 BRCA1 mutation carriers (2,997 with breast cancer, 705 with ovarian cancer, and 2,039 cancer free women) and 3,339 BRCA2 mutation carriers (1,846 with breast cancer, 207 with ovarian cancer, and 1,286 cancer free women) from 16 centers. Genotyping was accomplished using TaqMan(®) allelic discrimination or matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Data were analyzed within a retrospective cohort approach, stratified by country of origin and Ashkenazi Jewish origin. The per-allele hazard ratio (HR) for breast cancer was 1.02 (95% CI 0.93-1.12, P = 0.66) for BRCA1 mutation carriers and 0.92 (95% CI 0.82-1.04, P = 0.17) for BRCA2 mutation carriers. Results remained unaltered when analysis excluded prevalent breast cancer cases. Similarly, the per-allele HR for ovarian cancer was 1.01 (95% CI 0.84-1.20, P = 0.95) for BRCA1 mutation carriers and 0.9 (95% CI 0.66-1.22, P = 0.45) for BRCA2 mutation carriers. The risk did not change when carriers of the 6174delT mutation were excluded. There was a lack of association of the KL-VS Klotho variant with either breast or ovarian cancer risk in BRCA1 and BRCA2 mutation carriers.
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http://dx.doi.org/10.1007/s10549-011-1938-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3352679PMC
April 2012

Pathology of breast and ovarian cancers among BRCA1 and BRCA2 mutation carriers: results from the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA).

Cancer Epidemiol Biomarkers Prev 2012 Jan 5;21(1):134-47. Epub 2011 Dec 5.

Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary Care, University of Cambridge, Cambridge, United Kingdom.

Background: Previously, small studies have found that BRCA1 and BRCA2 breast tumors differ in their pathology. Analysis of larger datasets of mutation carriers should allow further tumor characterization.

Methods: We used data from 4,325 BRCA1 and 2,568 BRCA2 mutation carriers to analyze the pathology of invasive breast, ovarian, and contralateral breast cancers.

Results: There was strong evidence that the proportion of estrogen receptor (ER)-negative breast tumors decreased with age at diagnosis among BRCA1 (P-trend = 1.2 × 10(-5)), but increased with age at diagnosis among BRCA2, carriers (P-trend = 6.8 × 10(-6)). The proportion of triple-negative tumors decreased with age at diagnosis in BRCA1 carriers but increased with age at diagnosis of BRCA2 carriers. In both BRCA1 and BRCA2 carriers, ER-negative tumors were of higher histologic grade than ER-positive tumors (grade 3 vs. grade 1; P = 1.2 × 10(-13) for BRCA1 and P = 0.001 for BRCA2). ER and progesterone receptor (PR) expression were independently associated with mutation carrier status [ER-positive odds ratio (OR) for BRCA2 = 9.4, 95% CI: 7.0-12.6 and PR-positive OR = 1.7, 95% CI: 1.3-2.3, under joint analysis]. Lobular tumors were more likely to be BRCA2-related (OR for BRCA2 = 3.3, 95% CI: 2.4-4.4; P = 4.4 × 10(-14)), and medullary tumors BRCA1-related (OR for BRCA2 = 0.25, 95% CI: 0.18-0.35; P = 2.3 × 10(-15)). ER-status of the first breast cancer was predictive of ER-status of asynchronous contralateral breast cancer (P = 0.0004 for BRCA1; P = 0.002 for BRCA2). There were no significant differences in ovarian cancer morphology between BRCA1 and BRCA2 carriers (serous: 67%; mucinous: 1%; endometrioid: 12%; clear-cell: 2%). CONCLUSIONS/IMPACT: Pathologic characteristics of BRCA1 and BRCA2 tumors may be useful for improving risk-prediction algorithms and informing clinical strategies for screening and prophylaxis.
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http://dx.doi.org/10.1158/1055-9965.EPI-11-0775DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3272407PMC
January 2012

Characterisation of amplification patterns and target genes at chromosome 11q13 in CCND1-amplified sporadic and familial breast tumours.

Breast Cancer Res Treat 2012 Jun 16;133(2):583-94. Epub 2011 Oct 16.

Department of Oncology, Clinical Sciences, Lund University, Lund, Sweden.

Amplification of chromosomal region 11q13, containing the cell cycle regulatory gene CCND1, is frequently found in breast cancer and other malignancies. It is associated with the favourable oestrogen receptor (ER)-positive breast tumour phenotype, but also with poor prognosis and treatment failure. 11q13 spans almost 14 Mb and contains more than 200 genes and is affected by various patterns of copy number gains, suggesting complex mechanisms and selective pressure during tumour progression. In this study, we used 32 k tiling BAC array CGH to analyse 94 CCND1-amplified breast tumours from sporadic, hereditary, and familial breast cancers to fine map chromosome 11q13. A set containing 281 CCND1-non-amplified breast tumours was used for comparisons. We used gene expression data to further validate the functional effect of gene amplification. We identified six core regions covering 11q13.1-q14.1 that were amplified in different combinations. The major core contained CCND1, whereas two cores were found proximal of CCND1 and three distal. The majority of the CCND1-amplified tumours were ER-positive and classified as luminal B. Furthermore, we found that CCND1 amplification is associated with a more aggressive phenotype within histological grade 2 tumours and luminal A subtype tumours. Amplification was equally prevalent in familial and sporadic tumours, but strikingly rare in BRCA1- and BRCA2-mutated tumours. We conclude that 11q13 includes many potential target genes in addition to CCND1.
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http://dx.doi.org/10.1007/s10549-011-1817-3DOI Listing
June 2012

Common genetic variants and modification of penetrance of BRCA2-associated breast cancer.

PLoS Genet 2010 Oct 28;6(10):e1001183. Epub 2010 Oct 28.

Department of Epidemiology and Population Health and Department of Obstetrics and Gynecology and Women's Health, Albert Einstein College of Medicine, New York, New York, United States of America.

The considerable uncertainty regarding cancer risks associated with inherited mutations of BRCA2 is due to unknown factors. To investigate whether common genetic variants modify penetrance for BRCA2 mutation carriers, we undertook a two-staged genome-wide association study in BRCA2 mutation carriers. In stage 1 using the Affymetrix 6.0 platform, 592,163 filtered SNPs genotyped were available on 899 young (<40 years) affected and 804 unaffected carriers of European ancestry. Associations were evaluated using a survival-based score test adjusted for familial correlations and stratified by country of the study and BRCA2*6174delT mutation status. The genomic inflation factor (λ) was 1.011. The stage 1 association analysis revealed multiple variants associated with breast cancer risk: 3 SNPs had p-values<10(-5) and 39 SNPs had p-values<10(-4). These variants included several previously associated with sporadic breast cancer risk and two novel loci on chromosome 20 (rs311499) and chromosome 10 (rs16917302). The chromosome 10 locus was in ZNF365, which contains another variant that has recently been associated with breast cancer in an independent study of unselected cases. In stage 2, the top 85 loci from stage 1 were genotyped in 1,264 cases and 1,222 controls. Hazard ratios (HR) and 95% confidence intervals (CI) for stage 1 and 2 were combined and estimated using a retrospective likelihood approach, stratified by country of residence and the most common mutation, BRCA2*6174delT. The combined per allele HR of the minor allele for the novel loci rs16917302 was 0.75 (95% CI 0.66-0.86, ) and for rs311499 was 0.72 (95% CI 0.61-0.85, ). FGFR2 rs2981575 had the strongest association with breast cancer risk (per allele HR = 1.28, 95% CI 1.18-1.39, ). These results indicate that SNPs that modify BRCA2 penetrance identified by an agnostic approach thus far are limited to variants that also modify risk of sporadic BRCA2 wild-type breast cancer.
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http://dx.doi.org/10.1371/journal.pgen.1001183DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2965747PMC
October 2010

A locus on 19p13 modifies risk of breast cancer in BRCA1 mutation carriers and is associated with hormone receptor-negative breast cancer in the general population.

Nat Genet 2010 Oct 19;42(10):885-92. Epub 2010 Sep 19.

Centre for Cancer Genetic Epidemiology, Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK.

Germline BRCA1 mutations predispose to breast cancer. To identify genetic modifiers of this risk, we performed a genome-wide association study in 1,193 individuals with BRCA1 mutations who were diagnosed with invasive breast cancer under age 40 and 1,190 BRCA1 carriers without breast cancer diagnosis over age 35. We took forward 96 SNPs for replication in another 5,986 BRCA1 carriers (2,974 individuals with breast cancer and 3,012 unaffected individuals). Five SNPs on 19p13 were associated with breast cancer risk (P(trend) = 2.3 × 10⁻⁹ to P(trend) = 3.9 × 10⁻⁷), two of which showed independent associations (rs8170, hazard ratio (HR) = 1.26, 95% CI 1.17-1.35; rs2363956 HR = 0.84, 95% CI 0.80-0.89). Genotyping these SNPs in 6,800 population-based breast cancer cases and 6,613 controls identified a similar association with estrogen receptor-negative breast cancer (rs2363956 per-allele odds ratio (OR) = 0.83, 95% CI 0.75-0.92, P(trend) = 0.0003) and an association with estrogen receptor-positive disease in the opposite direction (OR = 1.07, 95% CI 1.01-1.14, P(trend) = 0.016). The five SNPs were also associated with triple-negative breast cancer in a separate study of 2,301 triple-negative cases and 3,949 controls (P(trend) = 1 × 10⁻⁷) to P(trend) = 8 × 10⁻⁵; rs2363956 per-allele OR = 0.80, 95% CI 0.74-0.87, P(trend) = 1.1 × 10⁻⁷
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http://dx.doi.org/10.1038/ng.669DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3130795PMC
October 2010

Genome-wide search for breast cancer linkage in large Icelandic non-BRCA1/2 families.

Breast Cancer Res 2010 16;12(4):R50. Epub 2010 Jul 16.

Department of Pathology, Landspitali-LSH v/Hringbraut, 101 Reykjavik, Iceland.

Introduction: A significant proportion of high-risk breast cancer families are not explained by mutations in known genes. Recent genome-wide searches (GWS) have not revealed any single major locus reminiscent of BRCA1 and BRCA2, indicating that still unidentified genes may explain relatively few families each or interact in a way obscure to linkage analyses. This has drawn attention to possible benefits of studying populations where genetic heterogeneity might be reduced. We thus performed a GWS for linkage on nine Icelandic multiple-case non-BRCA1/2 families of desirable size for mapping highly penetrant loci. To follow up suggestive loci, an additional 13 families from other Nordic countries were genotyped for selected markers.

Methods: GWS was performed using 811 microsatellite markers providing about five centiMorgan (cM) resolution. Multipoint logarithm of odds (LOD) scores were calculated using parametric and nonparametric methods. For selected markers and cases, tumour tissue was compared to normal tissue to look for allelic loss indicative of a tumour suppressor gene.

Results: The three highest signals were located at chromosomes 6q, 2p and 14q. One family contributed suggestive LOD scores (LOD 2.63 to 3.03, dominant model) at all these regions, without consistent evidence of a tumour suppressor gene. Haplotypes in nine affected family members mapped the loci to 2p23.2 to p21, 6q14.2 to q23.2 and 14q21.3 to q24.3. No evidence of a highly penetrant locus was found among the remaining families. The heterogeneity LOD (HLOD) at the 6q, 2p and 14q loci in all families was 3.27, 1.66 and 1.24, respectively. The subset of 13 Nordic families showed supportive HLODs at chromosome 6q (ranging from 0.34 to 1.37 by country subset). The 2p and 14q loci overlap with regions indicated by large families in previous GWS studies of breast cancer.

Conclusions: Chromosomes 2p, 6q and 14q are candidate sites for genes contributing together to high breast cancer risk. A polygenic model is supported, suggesting the joint effect of genes in contributing to breast cancer risk to be rather common in non-BRCA1/2 families. For genetic counselling it would seem important to resolve the mode of genetic interaction.
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http://dx.doi.org/10.1186/bcr2608DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2949638PMC
March 2011

Genomic subtypes of breast cancer identified by array-comparative genomic hybridization display distinct molecular and clinical characteristics.

Breast Cancer Res 2010 24;12(3):R42. Epub 2010 Jun 24.

Department of Oncology, Clinical Sciences, Lund University and Skåne University Hospital, Barngatan 2B, 5 Lund, Sweden.

Introduction: Breast cancer is a profoundly heterogeneous disease with respect to biologic and clinical behavior. Gene-expression profiling has been used to dissect this complexity and to stratify tumors into intrinsic gene-expression subtypes, associated with distinct biology, patient outcome, and genomic alterations. Additionally, breast tumors occurring in individuals with germline BRCA1 or BRCA2 mutations typically fall into distinct subtypes.

Methods: We applied global DNA copy number and gene-expression profiling in 359 breast tumors. All tumors were classified according to intrinsic gene-expression subtypes and included cases from genetically predisposed women. The Genomic Identification of Significant Targets in Cancer (GISTIC) algorithm was used to identify significant DNA copy-number aberrations and genomic subgroups of breast cancer.

Results: We identified 31 genomic regions that were highly amplified in > 1% of the 359 breast tumors. Several amplicons were found to co-occur, the 8p12 and 11q13.3 regions being the most frequent combination besides amplicons on the same chromosomal arm. Unsupervised hierarchical clustering with 133 significant GISTIC regions revealed six genomic subtypes, termed 17q12, basal-complex, luminal-simple, luminal-complex, amplifier, and mixed subtypes. Four of them had striking similarity to intrinsic gene-expression subtypes and showed associations to conventional tumor biomarkers and clinical outcome. However, luminal A-classified tumors were distributed in two main genomic subtypes, luminal-simple and luminal-complex, the former group having a better prognosis, whereas the latter group included also luminal B and the majority of BRCA2-mutated tumors. The basal-complex subtype displayed extensive genomic homogeneity and harbored the majority of BRCA1-mutated tumors. The 17q12 subtype comprised mostly HER2-amplified and HER2-enriched subtype tumors and had the worst prognosis. The amplifier and mixed subtypes contained tumors from all gene-expression subtypes, the former being enriched for 8p12-amplified cases, whereas the mixed subtype included many tumors with predominantly DNA copy-number losses and poor prognosis.

Conclusions: Global DNA copy-number analysis integrated with gene-expression data can be used to dissect the complexity of breast cancer. This revealed six genomic subtypes with different clinical behavior and a striking concordance to the intrinsic subtypes. These genomic subtypes may prove useful for understanding the mechanisms of tumor development and for prognostic and treatment prediction purposes.
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http://dx.doi.org/10.1186/bcr2596DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2917037PMC
November 2010

High-resolution genomic and expression analyses of copy number alterations in HER2-amplified breast cancer.

Breast Cancer Res 2010 6;12(3):R25. Epub 2010 May 6.

Department of Oncology, Clinical Sciences, Lund University, Barngatan 2B, Lund, Sweden.

Introduction: HER2 gene amplification and protein overexpression (HER2+) define a clinically challenging subgroup of breast cancer with variable prognosis and response to therapy. Although gene expression profiling has identified an ERBB2 molecular subtype of breast cancer, it is clear that HER2+ tumors reside in all molecular subtypes and represent a genomically and biologically heterogeneous group, needed to be further characterized in large sample sets.

Methods: Genome-wide DNA copy number profiling, using bacterial artificial chromosome (BAC) array comparative genomic hybridization (aCGH), and global gene expression profiling were performed on 200 and 87 HER2+ tumors, respectively. Genomic Identification of Significant Targets in Cancer (GISTIC) was used to identify significant copy number alterations (CNAs) in HER2+ tumors, which were related to a set of 554 non-HER2 amplified (HER2-) breast tumors. High-resolution oligonucleotide aCGH was used to delineate the 17q12-q21 region in high detail.

Results: The HER2-amplicon was narrowed to an 85.92 kbp region including the TCAP, PNMT, PERLD1, HER2, C17orf37 and GRB7 genes, and higher HER2 copy numbers indicated worse prognosis. In 31% of HER2+ tumors the amplicon extended to TOP2A, defining a subgroup of HER2+ breast cancer associated with estrogen receptor-positive status and with a trend of better survival than HER2+ breast cancers with deleted (18%) or neutral TOP2A (51%). HER2+ tumors were clearly distinguished from HER2- tumors by the presence of recurrent high-level amplifications and firestorm patterns on chromosome 17q. While there was no significant difference between HER2+ and HER2- tumors regarding the incidence of other recurrent high-level amplifications, differences in the co-amplification pattern were observed, as shown by the almost mutually exclusive occurrence of 8p12, 11q13 and 20q13 amplification in HER2+ tumors. GISTIC analysis identified 117 significant CNAs across all autosomes. Supervised analyses revealed: (1) significant CNAs separating HER2+ tumors stratified by clinical variables, and (2) CNAs separating HER2+ from HER2- tumors.

Conclusions: We have performed a comprehensive survey of CNAs in HER2+ breast tumors, pinpointing significant genomic alterations including both known and potentially novel therapeutic targets. Our analysis sheds further light on the genomically complex and heterogeneous nature of HER2+ tumors in relation to other subgroups of breast cancer.
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http://dx.doi.org/10.1186/bcr2568DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2917012PMC
November 2010

Identification of subtypes in human epidermal growth factor receptor 2--positive breast cancer reveals a gene signature prognostic of outcome.

J Clin Oncol 2010 Apr 15;28(11):1813-20. Epub 2010 Mar 15.

Department of Oncology, CREATE Health Strategic Center for TranslationalCancer Research, Lund University, Lund, Sweden.

PURPOSE Human epidermal growth factor receptor 2 (HER2) gene amplification or protein overexpression (HER2 positivity) defines a clinically challenging subgroup of patients with breast cancer (BC) with variable prognosis and response to therapy. We aimed to investigate the heterogeneous biologic appearance and clinical behavior of HER2-positive tumors using molecular profiling. PATIENTS AND METHODS Hierarchical clustering of gene expression data from 58 HER2-amplified tumors of various stage, histologic grade, and estrogen receptor (ER) status was used to construct a HER2-derived prognostic predictor that was further evaluated in several large independent BC data sets. RESULTS Unsupervised analysis identified three subtypes of HER2-positive tumors with mixed stage, histologic grade, and ER status. One subtype had a significantly worse clinical outcome. A prognostic predictor was created based on differentially expressed genes between the subtype with worse outcome and the other subtypes. The predictor was able to define patient groups with better and worse outcome in HER2-positive BC across multiple independent BC data sets and identify a sizable HER2-positive group with long disease-free survival and low mortality. Significant correlation to prognosis was also observed in basal-like, ER-negative, lymph node-positive, and high-grade tumors, irrespective of HER2 status. The predictor included genes associated with immune response, tumor invasion, and metastasis. CONCLUSION The HER2-derived prognostic predictor provides further insight into the heterogeneous biology of HER2-positive tumors and may become useful for improved selection of patients who need additional treatment with new drugs targeting the HER2 pathway.
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http://dx.doi.org/10.1200/JCO.2009.22.8775DOI Listing
April 2010