Association Study Of Breast Cancer Research Articles

Genome-wide association analyses of breast cancer in women of African ancestry identify new susceptibility loci and improve risk prediction.

We performed genome-wide association studies of breast cancer including 18,034 cases and 22,104 controls of African ancestry. Genetic variants at 12 loci were associated with breast cancer risk (P < 5 × 10-8), including associations of a low-frequency missense variant rs61751053 in ARHGEF38 with overall breast cancer (odds ratio (OR) = 1.48) and a common variant rs76664032 at chromosome 2q14.2 with triple-negative breast cancer (TNBC) (OR = 1.30). Approximately 15.4% of cases with TNBC carried six risk alleles in three genome-wide association study-identified TNBC risk variants, with an OR of 4.21 (95% confidence interval = 2.66-7.03) compared with those carrying fewer than two risk alleles. A polygenic risk score (PRS) showed an area under the receiver operating characteristic curve of 0.60 for the prediction of breast cancer risk, which outperformed PRS derived using data from females of European ancestry. Our study markedly increases the population diversity in genetic studies for breast cancer and demonstrates the utility of PRS for risk prediction in females of African ancestry.

Genome- and transcriptome-wide association studies of 386,000 Asian and European-ancestry women provide new insights into breast cancer genetics

By combining data from 160,500 individuals with breast cancer and 226,196 controls of Asian and European ancestry, we conducted genome- and transcriptome-wide association studies of breast cancer. We identified 222 genetic risk loci and 137 genes that were associated with breast cancer risk at a p<5.0×10-8 and a Bonferroni-corrected p<4.6×10-6, respectively. Of them, 32 loci and 15 genes showed a significantly different association between ER-positive and ER-negative breast cancer after Bonferroni correction. Significant ancestral differences in risk variant allele frequencies and their association strengths with breast cancer risk were identified. Of the significant associations identified in this study, 17 loci and 14 genes are located 1Mb away from any of the previously reported breast cancer risk variants. Pathways analyses including 221 putative risk genes identified multiple signaling pathways that may play a significant role in the development of breast cancer. Our study provides a comprehensive understanding of and new biological insights into the genetics of this common malignancy.

Identification of significant genes and therapeutic agents for breast cancer by integrated genomics

ABSTRACT Breast cancer is the most commonly diagnosed malignancy in women; thus, more cancer prevention research is urgently needed. The aim of this study was to predict potential therapeutic agents for breast cancer and determine their molecular mechanisms using integrated bioinformatics. Summary data from a large genome-wide association study of breast cancer was derived from the UK Biobank. The gene expression profile of breast cancer was from the Oncomine database. We performed a network-wide association study and gene set enrichment analysis to identify the significant genes in breast cancer. Then, we performed Gene Ontology analysis using the STRING database and conducted Kyoto Encyclopedia of Genes and Genomes pathway analysis using Cytoscape software. We verified our results using the Gene Expression Profile Interactive Analysis, PROgeneV2, and Human Protein Atlas databases. Connectivity map analysis was used to identify small-molecule compounds that are potential therapeutic agents for breast cancer. We identified 10 significant genes in breast cancer based on the gene expression profile and genome-wide association study. A total of 65 small-molecule compounds were found to be potential therapeutic agents for breast cancer.

Abstract 28: Integrating genomic and transcriptomic data to identify genetic loci associated with breast cancer risk in women of African ancestry

Abstract Background: To date, most genome-wide association studies (GWAS) of breast cancer have been conducted only among women of Asian and European ancestry. It is difficult to generalize results from those studies to women of African ancestry (AA). We conducted a large genetic association study of breast cancer in women of AA by analyzing both genetic and transcriptomic data. Methods: This collaborative study included 11,073 cases and 11,095 controls of AA who were participants in more than 15 studies conducted in the U.S. and Africa. Genotyping data were harmonized and imputed using the 1000 Genomes Project database as the reference. Imputed genotypes were used for GWAS to identify novel genetic risk loci for breast cancer. To search for susceptibility genes, we conducted a transcriptome-wide association study (TWAS), in which gene expression prediction models were built using genetic and tumor tissue RNA sequencing data from ~400 AA patients and used to impute expression levels of genes across the transcriptome for association analyses in all cases and controls included in the GWAS mentioned above. Results: We identified five loci (5p15.33, 5q31.3, 10q26.13, 18q12.1, and 19p13.11) associated with breast cancer risk at P &amp;lt; 5 × 10−8, including a novel locus at 5q31.3 (allelic odds ratio, OR = 1.18, 95% CI = 1.11-1.25, P = 4.65 × 10−8, nearby gene, ARHGAP26). This locus was also identified in association with estrogen receptor (ER) positive breast cancer at P &amp;lt; 5 × 10−8. Analyses stratified by ER status replicated known loci associated specifically with ER-positive (10q26.13) or ER-negative (2q14.2, 2p11.2, 5p15.33) breast cancer at P &amp;lt; 5 × 10−8. Of the 165 lead risk SNPs reported from previous breast cancer GWAS, 35 SNPs were replicated with the same association direction at P &amp;lt; 0.05. We constructed a polygenic risk score using these 35 replicated SNPs and the lead risk SNP at the novel locus and estimated the AUC to be 0.575. Of the 7,592 genes tested in the TWAS, we identified one gene, AC091053.1, with an association at a Bonferroni-corrected threshold of 6.64 × 10−6 (0.05/7,592). AC091053.1 is a long non-coding RNA gene at locus 11p15.4, where no risk variants have been identified in any previous breast cancer GWAS. AC091053.1 is located in the region of protein coding gene DENND2B, which acts as a regulator of MAPK1/ERK2 kinase and reduces the tumorigenic phenotype in cells. The gene AC091053.1 was associated with ER-positive breast cancer with P = 4.11 × 10−5 and ER-negative breast cancer with P = 0.032. Conclusions: Our study, the largest genetic study conducted to date in AA, identified novel breast cancer risk loci at 5q31.3 and 11p15.4 (AC091053.1) among women of AA and replicated &amp;gt;30 associations reported in previous studies. Studies with a larger sample size are needed to further investigate genetic variants and genes associated with breast cancer risk in AA women. Citation Format: Guochong Jia, Jie Ping, Yaohua Yang, Maureen Sanderson, Qiuyin Cai, Xingyi Guo, William J. Blot, Bingshan Li, Elisa V. Bandera, Manjeet K. Bolla, Montserrat García-Closas, Douglas F. Easton, Mary K. Fadden, Jian Gu, Dezheng Huo, Esther M. John, Kathryn L. Lunetta, Olufunmilayo I. Olopade, Xiang Shu, Melissa A. Troester, Song Yao, Breast Cancer Association Consortium, Andrew F. Olshan, Christine B. Ambrosone, Christopher A. Haiman, Jirong Long, Julie R. Palmer, Wei Zheng. Integrating genomic and transcriptomic data to identify genetic loci associated with breast cancer risk in women of African ancestry [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 28.

Abstract B065: A framework for transcriptome-wide association studies in breast cancer in diverse study populations

Abstract The relationship between germline genetic variation and breast cancer survival is largely unknown, especially in understudied minority populations. Traditional genome-wide association studies (GWAS) have interrogated survival associations in cohorts of predominantly European ancestries but are often underpowered due to subtype heterogeneity in breast cancer and a wide range of clinical covariates. Furthermore, these analyses tend to detect loci in non-coding regions, which require follow-up functional studies to interpret. Recent work in transcriptome-wide association studies (TWAS) has shown increased power in detecting functionally-relevant, trait-associated loci by leveraging information from expression quantitative trait loci (eQTLs) in external reference panels in relevant tissues. However, race-specific reference panels for TWAS may be needed to draw correct inference in large, ethnically-heterogeneous cohorts, and such panels for breast cancer are lacking. In this work, we provide a framework for TWAS for breast cancer in diverse populations, using data from the Carolina Breast Cancer Study (CBCS), a population-based cohort that oversampled for women self-identifying as African American. Using Nanostring expression data from CBCS, we perform an eQTL analysis for 417 breast cancer-related genes to train race-stratified predictive models of tumor expression from germline genotypes. We use these models to impute expression in held-out samples from the CBCS and in The Cancer Genome Atlas, using a permutation method to assess predictive performance accounting for sampling variability. We find that these race-stratified expression models are not always applicable across race, depending on the imputation cohort. Furthermore, their predictive performance varies by breast cancer subtypes. Lastly, we conduct a small-scale TWAS for breast cancer mortality in CBCS (N = 3,828), controlling for covariates used in previous GWAS for breast cancer survival. At an false discovery rate-adjusted P-value less than 0.1, adjusting for self-reported race, we find hazardous associations near CAPN13 (2p23.1), VAV3 (1p13.3), and BLK (8p23.1) and a protective association near SERPINB5 (18q21.33) in TWAS that are underpowered in GWAS. This approach shows increased power for detection of survival-associated genomic loci, demonstrating the relative strength of TWAS over GWAS. A carefully implemented TWAS is an efficient alternative to GWAS for understanding the genetic architecture underpinning breast cancer outcomes in diverse human populations and across biologically distinct tumor types. Citation Format: Arjun Bhattacharya, Montserrat García-Closas, Andrew F. Olshan, Charles M. Perou, Melissa A. Troester, Michael I Love. A framework for transcriptome-wide association studies in breast cancer in diverse study populations [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr B065.

A framework for transcriptome-wide association studies in breast cancer in diverse study populations

BackgroundThe relationship between germline genetic variation and breast cancer survival is largely unknown, especially in understudied minority populations who often have poorer survival. Genome-wide association studies (GWAS) have interrogated breast cancer survival but often are underpowered due to subtype heterogeneity and clinical covariates and detect loci in non-coding regions that are difficult to interpret. Transcriptome-wide association studies (TWAS) show increased power in detecting functionally relevant loci by leveraging expression quantitative trait loci (eQTLs) from external reference panels in relevant tissues. However, ancestry- or race-specific reference panels may be needed to draw correct inference in ancestrally diverse cohorts. Such panels for breast cancer are lacking.ResultsWe provide a framework for TWAS for breast cancer in diverse populations, using data from the Carolina Breast Cancer Study (CBCS), a population-based cohort that oversampled black women. We perform eQTL analysis for 406 breast cancer-related genes to train race-stratified predictive models of tumor expression from germline genotypes. Using these models, we impute expression in independent data from CBCS and TCGA, accounting for sampling variability in assessing performance. These models are not applicable across race, and their predictive performance varies across tumor subtype. Within CBCS (N = 3,828), at a false discovery-adjusted significance of 0.10 and stratifying for race, we identify associations in black women near AURKA, CAPN13, PIK3CA, and SERPINB5 via TWAS that are underpowered in GWAS.ConclusionsWe show that carefully implemented and thoroughly validated TWAS is an efficient approach for understanding the genetics underpinning breast cancer outcomes in diverse populations.

385P - Identifying CASP8 polymorphisms associated with breast cancer risk in an Iranian population

BackgroundIntroduction: Breast Cancer is one of the most common cancer in Iranian women. Whole genome association study of breast cancer have recognized various single nucleotide polymorphisms (SNPs) that are related with increased breast cancer risk in the population. This study aimed at assessing the correlation between caspase-8 (CASP8) gene polymorphisms (rs3754934 and rs12990906) and the pathogenesis of breast cancer in Northeast of Iran. MethodsIn a case- control study a total of 450 breast cancer cases and 553 healthy subjects were included in this study. Polymorphisms were genotyped by amplification-refractory mutation system (ARMS). The chi-squared test was used to calculate Odds ratio (OR) with 95% confidence interval to determine the relationship between CASP8 polymorphisms and breast cancer risk. ResultsAccording to the results, after adjustment for confounding factors, rs3754934 in dominant model (CA+AA vs. CC) [p = 0.004, OR = 0.49 95% CI (0.27-0.78)] and rs12990906 in allelic model (T vs. C) [p = 0.026, OR = 1.27, 95%CI (1.03-1.58)] were associated with the risk of breast cancer in this population. We did not find any association with breast cancer risk factors, clinical and pathologic features and prognosis and considered polymorphisms. ConclusionsPolymorphisms of CASP8 gene may have a crucial role in association with the risk of breast cancer. However, further larger studies can confirm such findings. An understanding of the mode of action of these variants will aid individual-level breast cancer risk prediction. Legal entity responsible for the studyMashhad University of Medical Sciences. FundingMashhad University of Medical Sciences. DisclosureAll authors have declared no conflicts of interest.

Genetic Variant Set-Based Tests Using the Generalized Berk–Jones Statistic With Application to a Genome-Wide Association Study of Breast Cancer

Studying the effects of groups of single nucleotide polymorphisms (SNPs), as in a gene, genetic pathway, or network, can provide novel insight into complex diseases such as breast cancer, uncovering new genetic associations and augmenting the information that can be gleaned from studying SNPs individually. Common challenges in set-based genetic association testing include weak effect sizes, correlation between SNPs in a SNP-set, and scarcity of signals, with individual SNP effects often ranging from extremely sparse to moderately sparse in number. Motivated by these challenges, we propose the Generalized Berk–Jones (GBJ) test for the association between a SNP-set and outcome. The GBJ extends the Berk–Jones statistic by accounting for correlation among SNPs, and it provides advantages over the Generalized Higher Criticism test when signals in a SNP-set are moderately sparse. We also provide an analytic p-value calculation for SNP-sets of any finite size, and we develop an omnibus statistic that is robust to the degree of signal sparsity. An additional advantage of our work is the ability to conduct inference using individual SNP summary statistics from a genome-wide association study (GWAS). We evaluate the finite sample performance of the GBJ through simulation and apply the method to identify breast cancer risk genes in a GWAS conducted by the Cancer Genetic Markers of Susceptibility Consortium. Our results suggest evidence of association between FGFR2 and breast cancer and also identify other potential susceptibility genes, complementing conventional SNP-level analysis. Supplementary materials for this article, including a standardized description of the materials available for reproducing the work, are available as an online supplement.

Abstract 3257: Polygenic risk score, stage, and mode of detection in relation to breast cancer risk

Abstract Identification of increasing numbers of breast cancer risk variants holds promise to improve risk prediction and identify population subgroups that could benefit from targeted prevention and early detection. We aimed to examine whether women with increased polygenic risk are more likely to be diagnosed with symptomatic breast cancer. A case-control study including data collected from interviews, DNA from saliva, and cancer registry data collected between 2001-2007 (4,315 cases, 3,919 controls) was used to construct a polygenic risk score (PRS). Single nucleotide polymorphisms (SNPs, N=98) were selected from recently published genome-wide association studies of breast cancer and breast density, and comparative rat genome studies. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CI) associated with the SNPs. SNPs with p-values ≤0.10 (N=24) were used to construct quintiles of the PRS by multiplying the log-odds of the SNPs by the number of risk alleles; multivariable logistic regression models evaluated all women and strata of women defined by method of detection and stage at diagnosis. Odds ratios were adjusted for age, family history of breast cancer, age at menopause/menopausal status, body mass index, parity, and age at first birth. Overall, PRS quintile categories were associated with breast cancer risk in a dose response manner (Q1: OR=1, reference; Q2 OR=1.36, 95% CI 1.16-1.58; Q3 OR=1.66, 95% CI 1.43-1.93; Q4 OR=1.83, 95% CI 1.58-2.12; Q5 OR=2.58, 95% CI 2.23-2.98). Evaluated on a continuous scale, the PRS was associated with an OR=1.38 for a 1-unit change in the standard deviation (SD), 95% CI 1.32-1.45. Odds ratios were essentially unchanged when stratified by method of detection (p-value=0.40). The odds ratio of breast cancer associated with the continuous PRS was elevated among women diagnosed with advanced breast cancer: DCIS, OR=1.36, 95% CI 1.26-1.47 per 1 SD; localized OR=1.37, 95% CI 1.30-1.45 per 1 SD; regional OR=1.38, 95% CI 1.28-1.48 per 1 SD; and distant OR=1.82, 95% CI 1.39-2.40. These results suggest that polygenic risk scores are strongly related to breast cancer risk, that the association does not vary by method of breast cancer detection, but that the association is strongest for metastatic breast cancer. Citation Format: Amy Trentham-Dietz, John M. Hampton, Irene M. Ong, C David Page, Michael N. Gould, Jill D. Haag, Polly A. Newcomb, James D. Shull, Elizabeth S. Burnside. Polygenic risk score, stage, and mode of detection in relation to breast cancer risk [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3257.

Genetic variation in the Hippo pathway and breast cancer risk in women of African ancestry.

Gene expression changes within the Hippo pathway were found to be associated with large tumor size and metastasis in breast cancer. The combined effect of genetic variants in genes of this pathway may have a causal role in breast cancer development. We examined 7086 SNPs that were not highly correlated (r2 < 0.8) in 35 Hippo pathway genes using data from the genome-wide association study of breast cancer from the Root Consortium, which includes 3686 participants of African ancestry from Nigeria, United States of America, and Barbados: 1657 cases (403 estrogen receptor-positive [ER+], 374 ER-) and 2029 controls. Gene-level analyses were conducted using improved AdaJoint test for large-scale genetic association studies adjusting for age, study site and the first four eigenvectors from the principal component analysis. SNP-level analyses were conducted with logistic regression. The Hippo pathway was significantly associated with risk of ER+ breast cancer (pathway-level P = 0.019), with WWC1 (Padj = 0.04) being the leading gene. The pathway-level significance was lost without WWC1 (P = 0.12). rs147106204 in the WWC1 gene was the most statistically significant SNP after gene-level adjustment for multiple comparisons (OR = 0.53, 95%CI = 0.41-0.70, Padj = 0.025). We found evidence of an association between genetic variations in the Hippo pathway and ER+ breast cancer. Moreover, WWC1 was identified as the most important genetic susceptibility locus highlighting the importance of genetic epidemiology studies of breast cancer in understudied populations.

Association analysis identifies 65 new breast cancer risk loci.

Breast cancer risk is influenced by rare coding variants in susceptibility genes such as BRCA1 and many common, mainly non-coding variants. However, much of the genetic contribution to breast cancer risk remains unknown. We report results from a genome-wide association study (GWAS) of breast cancer in 122,977 cases and 105,974 controls of European ancestry and 14,068 cases and 13,104 controls of East Asian ancestry1. We identified 65 new loci associated with overall breast cancer at p<5x10-8. The majority of credible risk SNPs in the new loci fall in distal regulatory elements, and by integrating in-silico data to predict target genes in breast cells at each locus, we demonstrate a strong overlap between candidate target genes and somatic driver genes in breast tumours. We also find that heritability of breast cancer due to all SNPs in regulatory features was 2-5-fold enriched relative to the genome-wide average, with strong enrichment for particular transcription factor binding sites. These results provide further insight into genetic susceptibility to breast cancer and will improve the utility of genetic risk scores for individualized screening and prevention.

Abstract 1312: Genetic variation in the Hippo pathway and breast cancer risk in women of African ancestry in the ROOT Consortium

Abstract Background: The Hippo pathway controls organ growth by regulating cell proliferation and apoptosis. To our knowledge, it is still unclear about its role in the development of breast cancer. Identifying the relevant genes and single-nucleotide polymorphisms (SNPs) should shed light on the pathway’s mechanism in carcinogenesis. Methods: We examined 47,419 SNPs in 37 Hippo pathway genes in the genome wide association study of breast cancer conducted in the African Diaspora (ROOT consortium), which included 3,686 participants of African ancestry from Nigeria, USA, and Barbados (1,657 cases and 2,029 controls). Gene-level analyses were conducted using the adaptive rank truncated product (ARTP) test for 10,771 SNPs that weren’t highly correlated (r2 &amp;lt; 0.8), and SNP-level analyses were conducted with logistic regression. Results: The Hippo pathway was significantly associated with risk of estrogen receptor positive (ER+) breast cancer (pathway-level P=0.028). Gene-based analyses revealed that WWC1 (gene-level P=0.001) was responsible for this association, with rs116516633 in this gene being statistically significant after gene-level adjustment for multiple comparisons [odds ratio (OR) =0.53 for each G allele, 95% confidence interval (CI) =0.41-0.70, Padj=0.002]. In addition, two SNPs in LATS2 (rs142900440, OR=0.42, 95% CI: 0.28-0.64; rs58674288, OR=0.38, 95% CI =0.24-0.61) were associated with risk of ER+ breast cancer. In the analysis of ER- breast cancer risk, rs2579161 in DLG5 (OR=1.38, 95% CI: 1.17-1.63) and rs11062429 in TEAD4 (OR=1.39, 95% CI: 1.17-1.64) were statistically significant. These associations remained significant after Bonferroni-correction at the gene-wide level (all P&amp;lt; 0.05). Conclusions: We found evidence of associations of the Hippo pathway with ER+ breast cancer risk in women of African ancestry. Our findings supported the potential mechanism that WWC1 functions as an upstream member of the pathway, and highlighted the importance of further studies. Table 1.Gene-wide significant tested SNPs for all breast cancer, ER+ tumors or ER- tumorsAll cases vs controlsER+ cases vs controlsER- cases vs controlsGene-SNPFunctionMajor/minor allelesMinor allele frequency among controlsOR (95% CI)PadjOR (95% CI)PadjOR (95% CI)PadjOverallTEAD1-rs16911695IntronG/A0.241.24 (1.11-1.39)0.101.30 (1.07-1.58)1.001.34 (1.10-1.63)1.00ER+LATS2-rs142900440IntronT/C0.040.78 (0.61-0.98)1.000.42 (0.28-0.64)0.010.80 (0.54-1.19)1.00LATS2-rs58674288IntronC/T0.030.73 (0.56-0.95)1.000.38 (0.24-0.61)0.010.70 (0.45-1.08)1.00WWC1-rs116516633Non-coding transcript variantA/G0.100.82 (0.71-0.96)1.000.53 (0.41-0.70)0.0020.81 (0.62-1.06)1.00ER-DLG5-rs2579161Upstream gene variantG/A0.491.08 (0.98-1.19)1.000.99 (0.85-1.17)1.001.38 (1.17-1.63)0.03TEAD4-rs11062429Downstream gene variantC/G0.431.01 (0.92-1.11)1.000.94 (0.79-1.00)1.001.39 (1.17-1.64)0.047 Citation Format: Shengfeng Wang, Yonglan Zheng, Temidayo O. Ogundiran, Oladosu Ojengbede, Wei Zheng, Katherine L. Nathanson, Barbara Nemesure, Stefan Ambs, Dezheng Huo, Olufunmilayo I. Olopade. Genetic variation in the Hippo pathway and breast cancer risk in women of African ancestry in the ROOT Consortium [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1312. doi:10.1158/1538-7445.AM2017-1312

Association of breast cancer risk and the mTOR pathway in women of African ancestry in 'The Root' Consortium.

Functional studies have elucidated the role of the mammalian target of rapamycin (mTOR) pathway in breast carcinogenesis, but to date, there is a paucity of data on its contribution to breast cancer risk in women of African ancestry. We examined 47628 SNPs in 61 mTOR pathway genes in the genome wide association study of breast cancer in the African Diaspora study (The Root consortium), which included 3686 participants (1657 cases). Pathway- and gene-level analyses were conducted using the adaptive rank truncated product (ARTP) test for 10994 SNPs that were not highly correlated (r2 < 0.8). Odds ratio (OR) and 95% confidence interval (CI) were estimated with logistic regression for each single-nucleotide polymorphism. The mTOR pathway was significantly associated with overall and estrogen receptor-negative (ER-) breast cancer risk (P = 0.003 and 0.03, respectively). PRKAG3 (Padj = 0.0018) and RPS6KA3 (Padj = 0.061) were the leading genes for the associations with overall breast cancer risk and ER- breast cancer risk, respectively. rs190843378 in PRKAG3 was statistically significant after gene-level adjustment for multiple comparisons (OR = 0.50 for each T allele, 95% CI = 0.38-0.66, Padj = 3.6E-05), with a statistical power of 0.914. These results provide new insights on the biological relevance of the mTOR pathway in breast cancer progression and underscore the need for more genetic epidemiology studies of breast cancer in the African Diaspora.

Genome-Wide Association Study to Identify Susceptibility Loci That Modify Radiation-Related Risk for Breast Cancer After Childhood Cancer.

Childhood cancer survivors treated with chest-directed radiotherapy have substantially elevated risk for developing breast cancer. Although genetic susceptibility to breast cancer in the general population is well studied, large-scale evaluation of breast cancer susceptibility after chest-directed radiotherapy for childhood cancer is lacking. We conducted a genome-wide association study of breast cancer in female survivors of childhood cancer, pooling two cohorts with detailed treatment data and systematic, long-term follow-up: the Childhood Cancer Survivor Study and St. Jude Lifetime Cohort. The study population comprised 207 survivors who developed breast cancer and 2774 who had not developed any subsequent neoplasm as of last follow-up. Genotyping and subsequent imputation yielded 16 958 466 high-quality variants for analysis. We tested associations in the overall population and in subgroups stratified by receipt of lower than 10 and 10 or higher gray breast radiation exposure. We report P values and pooled per-allele risk estimates from Cox proportional hazards regression models. All statistical tests were two-sided. Among survivors who received 10 or higher gray breast radiation exposure, a locus on 1q41 was associated with subsequent breast cancer risk (rs4342822, nearest gene PROX1 , risk allele frequency in control subjects [RAF controls ] = 0.46, hazard ratio = 1.92, 95% confidence interval = 1.49 to 2.44, P = 7.09 × 10 -9 ). Two rare variants also showed potentially promising associations (breast radiation ≥10 gray: rs74949440, 11q23, TAGLN , RAF controls = 0.02, P = 5.84 × 10 -8 ; <10 gray: rs17020562, 1q32.3, RPS6KC1 , RAF controls = 0.0005, P = 6.68 × 10 -8 ). Associations were restricted to these dose subgroups, with consistent findings in the two survivor cohorts. Our study provides strong evidence that germline genetics outside high-risk syndromes could modify the effect of radiation exposure on breast cancer risk after childhood cancer.

Genome-wide association studies in women of African ancestry identified 3q26.21 as a novel susceptibility locus for oestrogen receptor negative breast cancer.

Multiple breast cancer loci have been identified in previous genome-wide association studies, but they were mainly conducted in populations of European ancestry. Women of African ancestry are more likely to have young-onset and oestrogen receptor (ER) negative breast cancer for reasons that are unknown and understudied. To identify genetic risk factors for breast cancer in women of African descent, we conducted a meta-analysis of two genome-wide association studies of breast cancer; one study consists of 1,657 cases and 2,029 controls genotyped with Illumina’s HumanOmni2.5 BeadChip and the other study included 3,016 cases and 2,745 controls genotyped using Illumina Human1M-Duo BeadChip. The top 18,376 single nucleotide polymorphisms (SNP) from the meta-analysis were replicated in the third study that consists of 1,984 African Americans cases and 2,939 controls. We found that SNP rs13074711, 26.5 Kb upstream of TNFSF10 at 3q26.21, was significantly associated with risk of oestrogen receptor (ER)-negative breast cancer (odds ratio [OR]=1.29, 95% CI: 1.18-1.40; P = 1.8 × 10 − 8). Functional annotations suggest that the TNFSF10 gene may be involved in breast cancer aetiology, but further functional experiments are needed. In addition, we confirmed SNP rs10069690 was the best indicator for ER-negative breast cancer at 5p15.33 (OR = 1.30; P = 2.4 × 10 − 10) and identified rs12998806 as the best indicator for ER-positive breast cancer at 2q35 (OR = 1.34; P = 2.2 × 10 − 8) for women of African ancestry. These findings demonstrated additional susceptibility alleles for breast cancer can be revealed in diverse populations and have important public health implications in building race/ethnicity-specific risk prediction model for breast cancer.

Classification of Missense Variants in XRCC2 by Functional Analysis: Implications for Breast Cancer Association Studies.

XRCC2 belongs to the family of RAD51 paralogs, which are involved in homologous recombination repair (HRR) of DNA double-strand breaks. Variants in XRCC2 have recently been suggested to increase the risk for breast cancer. However, this finding could not be confirmed in a second study. Both case-control studies lacked power due to the rarity of deleterious XRCC2 mutations, and therefore rare missense variants predicted to be damaging by in silico analysis had been included in the analyses. But is incorporating purely in silico predictions for variant pathogenicity advised when conducting association studies? In this issue, Hilbers et al. (Hum Mutat 37:914–925, 2016) examined 23 previously reported XRCC2 missense variants with four different in silico prediction algorithms, including AlignGVGD, SIFT, PolyPhen2, and CADD, to estimate whether the variants were likely to be pathogenic. The functional effects of the XRCC2 missense variants were subsequently examined by testing their ability to complement the DNA repair phenotype of XRCC2-deficient cells, as well as measuring the efficiency of the variants to perform HRR in hamster and human cells. The experiments revealed that the in silico predictions correlated poorly with the observed functional effects. When the novel functional data were included in case-control studies, there no longer was an association with breast cancer. The authors conclude that if XRCC2 variants predispose to breast cancer, the associated variants are likely to be restricted to protein-truncating mutations as well as few missense variants. Next-generation sequencing is expected to increase the number of rare variants identified in novel cancer-predisposing genes, which poses challenges to risk estimation through patient cohorts and cosegregation analysis. The study by Hilbers et al. highlights the importance of functional analysis of variants of unknown clinical significance and demonstrates the pitfalls in establishing an association between rare missense variants and disease risk.

Genome-wide association study of breast cancer in Latinas identifies novel protective variants on 6q25

The genetic contributions to breast cancer development among Latinas are not well understood. Here we carry out a genome-wide association study of breast cancer in Latinas and identify a genome-wide significant risk variant, located 5′ of the Estrogen Receptor 1 gene (ESR1; 6q25 region). The minor allele for this variant is strongly protective (rs140068132: odds ratio (OR) 0.60, 95% confidence interval (CI) 0.53–0.67, P=9 × 10−18), originates from Indigenous Americans and is uncorrelated with previously reported risk variants at 6q25. The association is stronger for oestrogen receptor-negative disease (OR 0.34, 95% CI 0.21–0.54) than oestrogen receptor-positive disease (OR 0.63, 95% CI 0.49–0.80; P heterogeneity=0.01) and is also associated with mammographic breast density, a strong risk factor for breast cancer (P=0.001). rs140068132 is located within several transcription factor-binding sites and electrophoretic mobility shift assays with MCF-7 nuclear protein demonstrate differential binding of the G/A alleles at this locus. These results highlight the importance of conducting research in diverse populations.

Abstract LB-299: Genome wide association study of breast cancer in Latinas identifies protective variants of Indigenous American origin on 6q25

Abstract Background: Multiple breast cancer genome-wide association studies (GWAS) have been conducted, with most samples analyzed being of European or Asian origin. No GWAS has been published to date on US Latinas or Latin American women. Previous studies have demonstrated that among Latina women, those with the highest Indigenous American ancestry are protected from breast cancer. We performed the first genome-wide association study of breast cancer in Latinas in a total of 1523 cases and 3221 controls and validated the strongest associations in an additional 977 Latina cases and 1158 controls. Methods: For the discovery phase, samples were genotyped with either the 6.0 Affymetrix array or Illumina Infinitum 660W/Omni 2.5 arrays. Additional genotypes were imputed from 1000 genomes and the final analysis included ∼7 million SNPs. SNPs for replication were genotyped using Sequenom. Logistic regression analyses included the first 10 principal components as covariates. Results: We identified two new variants, located 5’ of the ESR1 gene (6q25 region), which are strongly associated with breast cancer in this population. The minor allele for these variants is strongly protective (rs140068132: OR 0.61, 95%CI 0.48-0.75, p=3x10-13 &amp; rs147157845: OR 0.63 95% CI 0.49-0.76; p =2x10-12). These alleles are present only in Latinos, correlate with Indigenous American ancestry, and are uncorrelated with previously reported risk variants in the ESR1 region. We found a strong association for both ER-positive and ER-negative breast cancer, but significantly more protection for ER-negative disease (p=0.014). The rs140068132 variant is also associated with breast density. The average breast density among women who are homozygous for the protective allele is approximately half of that of women homozygous for the common allele [Mean (sd) density for Homozygous GG = 9 (8); Homozygous AA = 17 (14), p 0.0009]. rs140068132, is located within a putative binding region for multiple transcription factors. MAPPER predicts disruption of putative transcription factor binding sites for the rare allele at rs140068132 but not rs147157845. Electromotility shift assays showed differential binding of the two alleles at the rs140068132 locus, with the protective allele (G) showing substantially reduced binding affinity compared to the common A allele. Conclusions: The variants at this locus represent, to our knowledge, the strongest genome wide effect size on breast cancer for a common variant (frequency &amp;gt;0.05 in any major population). These results may help in understanding the previous observations of lower breast cancer risk among Latina women with more Indigenous American ancestry and highlight the importance of conducting GWAS in diverse populations. Citation Format: Laura Fejerman, Nasim Ahmadiyeh, Donglei Hu, Scott Huntsman, Kenneth Beckman, Jennifer Caswell, Esther M. John, Gabriela Torres-Mejia, Luis Carvajal-Carmona, Magdalena Echeverry, Anna Marie Tuazon, Carolina Ramirez, COLUMBUS Consortium, Christopher Gignoux, Celeste Eng, Esteban Gonzalez-Burchard, Brian Henderson, Loic Le Marchand, Eliseo J. Perez-Stable, Christopher A. Haiman, Elad Ziv. Genome wide association study of breast cancer in Latinas identifies protective variants of Indigenous American origin on 6q25. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-299. doi:10.1158/1538-7445.AM2014-LB-299

The saga of the many studies wrongly associating mitochondrial DNA with breast cancer.

BackgroundA large body of genetic research has focused on the potential role that mitochondrial DNA (mtDNA) variants might play on the predisposition to common and complex (multi-factorial) diseases. It has been argued however that many of these studies could be inconclusive due to artifacts related to genotyping errors or inadequate design.MethodsAnalyses of the data published in case–control breast cancer association studies have been performed using a phylogenetic-based approach. Variation observed in these studies has been interpreted in the light of data available on public resources, which now include over >27,000 complete mitochondrial sequences and the worldwide phylogeny determined by these mitogenomes. Complementary analyses were carried out using public datasets of partial mtDNA sequences, mainly corresponding to control-region segments.ResultsBy way of example, we show here another kind of fallacy in these medical studies, namely, the phenomenon of SNP-SNP interaction wrongly applied to haploid data in a breast cancer study. We also reassessed the mutually conflicting studies suggesting some functional role of the non-synonymous polymorphism m.10398A > G (ND3 subunit of mitochondrial complex I) in breast cancer. In some studies, control groups were employed that showed an extremely odd haplogroup frequency spectrum compared to comparable information from much larger databases. Moreover, the use of inappropriate statistics signaled spurious “significance” in several instances.ConclusionsEvery case–control study should come under scrutiny in regard to the plausibility of the control-group data presented and appropriateness of the statistical methods employed; and this is best done before potential publication.

Breast Cancer Association Studies in a Han Chinese Population using 10 European-ancestry-associated Breast Cancer Susceptibility SNPs

Genome-wide association studies (GWAS) have identified various genetic susceptibility loci for breast cancer based mainly on European-ancestry populations. Differing linkage disequilibrium patterns exist between European and Asian populations. Ten SNPs (rs2075555 in COL1A1, rs12652447 in FBXL17, rs10941679 in 5p12/MRPS30, rs11878583 in ZNF577, rs7166081 in SMAD3, rs16917302 in ZNF365, rs311499 in 20q13.3, rs1045485 in CASP8, rs12964873 in CDH1 and rs8170 in 19p13.1) were here genotyped in 1009 Chinese females (487 patients with breast cancer and 522 control subjects) using the Sequenom MassARRAY iPLEX platform. Association analysis based on unconditional logistic regression was carried out to determine the odds ratio (OR) and 95% confidence interval (95% CI) for each SNP. Stratification analyses were carried out based on the estrogen receptor (ER) and progesterone receptor (PR) status. Among the 10 SNPs, rs10941679 showed significant association with breast cancer when differences between the case and control groups in this Han Chinese population were compared (30.09% GG, 45.4% GA and 23.7% AA; P = 0.012). Four SNPs (rs311499, rs1045485, rs12964873 and rs8170) showed no polymorphisms in our study. The remaining five SNPs showed no association with breast cancer in the present population. Immunohistochemical tests showed that rs2075555 was associated with ER status; the AA genotype showed greater association with ER negative than ER positive (OR = 0.54, 95% CI, 0.29-0.99; P = 0.046). AA of rs7166081 was also associated with ER status, but showed a greater association with ER positive than negative (OR = 1.59, 95% CI = 1.04-2.44; P = 0.031). However, no significant associations were found among the SNPs and PR status. In this study using a Han Chinese population, rs10941679 was the only SNP associated with breast cancer risk, indicating a difference between European and Chinese populations in susceptibility loci. Therefore, confirmation studies are necessary before utilization of these loci in Chinese.