Contribution of Germline Predisposition Gene Mutations to Breast Cancer Risk in African American Women

BACKGROUND

The risks of breast cancer in African American (AA) women associated with inherited mutations in breast cancer predisposition genes are not well defined. Thus, whether multigene germline hereditary cancer testing panels are applicable to this population is unknown. We assessed associations between mutations in panel-based genes and breast cancer risk in 5054 AA women with breast cancer and 4993 unaffected AA women drawn from 10 epidemiologic studies.

METHODS

Germline DNA samples were sequenced for mutations in 23 cancer predisposition genes using a QIAseq multiplex amplicon panel. Prevalence of mutations and odds ratios (ORs) for associations with breast cancer risk were estimated with adjustment for study design, age, and family history of breast cancer.

RESULTS

Pathogenic mutations were identified in 10.3% of women with estrogen receptor (ER)-negative breast cancer, 5.2% of women with ER-positive breast cancer, and 2.3% of unaffected women. Mutations in BRCA1, BRCA2, and PALB2 were associated with high risks of breast cancer (OR = 47.55, 95% confidence interval [CI] = 10.43 to >100; OR = 7.25, 95% CI = 4.07 to 14.12; OR = 8.54, 95% CI = 3.67 to 24.95, respectively). RAD51D mutations were associated with high risk of ER-negative disease (OR = 7.82, 95% CI = 1.61 to 57.42). Moderate risks were observed for CHEK2, ATM, ERCC3, and FANCC mutations with ER-positive cancer, and RECQL mutations with all breast cancer.

CONCLUSIONS

The study identifies genes that predispose to breast cancer in the AA population, demonstrates the validity of current breast cancer testing panels for use in AA women, and provides a basis for increased referral of AA patients for cancer genetic testing.

Germline variation in the insulin-like growth factor pathway and risk of Barrett's esophagus and esophageal adenocarcinoma

Genome-wide association studies (GWAS) of esophageal adenocarcinoma (EAC) and its precursor, Barrett's esophagus (BE), have uncovered significant genetic components of risk, but most heritability remains unexplained. Targeted assessment of genetic variation in biologically relevant pathways using novel analytical approaches may identify missed susceptibility signals. Central obesity, a key BE/EAC risk factor, is linked to systemic inflammation, altered hormonal signaling and insulin-like growth factor (IGF) axis dysfunction. Here, we assessed IGF-related genetic variation and risk of BE and EAC. Principal component analysis was employed to evaluate pathway-level and gene-level associations with BE/EAC, using genotypes for 270 single-nucleotide polymorphisms (SNPs) in or near 12 IGF-related genes, ascertained from 3295 BE cases, 2515 EAC cases and 3207 controls in the Barrett's and Esophageal Adenocarcinoma Consortium (BEACON) GWAS. Gene-level signals were assessed using Multi-marker Analysis of GenoMic Annotation (MAGMA) and SNP summary statistics from BEACON and an expanded GWAS meta-analysis (6167 BE cases, 4112 EAC cases, 17 159 controls). Global variation in the IGF pathway was associated with risk of BE (P = 0.0015). Gene-level associations with BE were observed for GHR (growth hormone receptor; P = 0.00046, false discovery rate q = 0.0056) and IGF1R (IGF1 receptor; P = 0.0090, q = 0.0542). These gene-level signals remained significant at q < 0.1 when assessed using data from the largest available BE/EAC GWAS meta-analysis. No significant associations were observed for EAC. This study represents the most comprehensive evaluation to date of inherited genetic variation in the IGF pathway and BE/EAC risk, providing novel evidence that variation in two genes encoding cell-surface receptors, GHR and IGF1R, may influence risk of BE.

Abstract PO-181: Associations of characteristics of hair dye and relaxer use with tumor clinicopathologic features among Black and White women with breast cancer

Introduction: In our previous findings from the Women’s Circle of Health Study (WCHS), we observed statistically significant associations between use of hair dye and relaxer, which contain potentially mutagenic and endocrine-disrupting chemicals, and increased breast cancer risk. In the current analysis, we sought to expand upon our earlier findings by assessing associations between hair product use and breast tumor clinicopathology. Methods: Risk factor data (including characteristics of hair product use) were collected through in-person interviews, and tumor clinicopathology data were abstracted from available pathology records of 2,998 breast cancer cases (2,227 Black, 771 White). Associations between hair product use and tumor clinicopathology were analyzed using multivariable-adjusted, binomial and multinomial logistic regression models. Further analysis was performed in subsets by race and estrogen receptor (ER) status. Results: Numerous characteristics of hair product use were associated with more aggressive tumor features. Longer (&gt;10 years) use of relaxers and earlier exposure to relaxers (≤12 years old at first use) were associated with increased odds of poorly differentiated tumors (OR 2.15, 95% CI: 1.08-4.28 and OR 2.00, 95% CI: 1.05-3.82, respectively).

History of regular relaxer use (OR 1.51, 95% CI: 1.23-1.87) and dual use of both hair dyes and relaxers (OR 1.40, 95% CI: 1.02-1.92) were associated with increased odds of ER- status. Compared to sole salon application, utilization of both salon and home- kit application types for hair dyes was associated with increased odds of higher tumor grade (moderately differentiated: OR 1.74, 95% CI: 1.05-2.87; poorly differentiated: OR 2.52, 95% CI: 1.51-4.20). These associations were consistent among Black, but not White, women. Combination use of salon and home-kit relaxer application types was associated with increased odds of tumors &gt;2.0 cm (OR 1.88, 95% CI: 1.27-2.77). Conclusions: While recent research has supported a connection between hair product use and breast cancer risk, this is the first study to examine the associations of hair product use with breast tumor features. Our findings showed that certain characteristics, particularly the magnitude of exposure to these products and application types of hair dye and relaxer, are associated with tumor features that are indicative of more aggressive phenotypes, including higher grade and ER- status. These findings generate new hypotheses about the potential impact of hair product use on breast cancer outcomes, warranting further study.

Citation Format: Rohan Rao, Jasmine A. McDonald, Emily S. Barrett, Dede Teteh, Susanne Montgomery, Bo Qin, Yong Lin, Chi-Chen Hong, Christine B. Ambrosone, Kitaw Demisse, Elisa V. Bandera, Adana A.M. Llanos. Associations of characteristics of hair dye and relaxer use with tumor clinicopathologic features among Black and White women with breast cancer [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PO-181.

Gene expression of adipokines and adipokine receptors in the tumor microenvironment: associations of lower expression with more aggressive breast tumor features

PURPOSE

Limited epidemiologic data are available on the expression of adipokines leptin (LEP) and adiponectin (ADIPOQ) and adipokine receptors (LEPR, ADIPOR1, ADIPOR2) in the breast tumor microenvironment (TME). The associations of gene expression of these biomarkers with tumor clinicopathology are not well understood.

METHODS

NanoString multiplexed assays were used to assess the gene expression levels of LEP, LEPR, ADIPOQ, ADIPOR1, and ADIPOR2 within tumor tissues among 162 Black and 55 White women with newly diagnosed breast cancer. Multivariate mixed effects models were used to estimate associations of gene expression with breast tumor clinicopathology (overall and separately among Blacks).

RESULTS

Black race was associated with lower gene expression of LEPR (P = 0.002) and ADIPOR1 (P = 0.01). Lower LEP, LEPR, and ADIPOQ gene expression were associated with higher tumor grade (P = 0.0007, P < 0.0001, and P < 0.0001, respectively) and larger tumor size (P < 0.0001, P = 0.0005, and P < 0.0001, respectively). Lower ADIPOQ expression was associated with ER- status (P = 0.0005), and HER2-enriched (HER2-E; P = 0.0003) and triple-negative (TN; P = 0.002) subtypes. Lower ADIPOR2 expression was associated with Ki67+ status (P = 0.0002), ER- status (P < 0.0001), PR- status (P < 0.0001), and TN subtype (P = 0.0002). Associations of lower adipokine and adipokine receptor gene expression with ER-, HER2-E, and TN subtypes were confirmed using data from The Cancer Genome Atlas (P-values < 0.005).

CONCLUSION

These findings suggest that lower expression of ADIPOQ, ADIPOR2, LEP, and LEPR in the breast TME might be indicators of more aggressive breast cancer phenotypes. Validation of these findings are warranted to elucidate the role of the adipokines and adipokine receptors in long-term breast cancer prognosis.

Effects of cooking methods on total isothiocyanate yield from cruciferous vegetables

Cruciferous vegetables are primary sources of dietary isothiocyanates (ITCs), a group of phytochemicals showing promising cancer-chemopreventive activities in multiple cancer models. However, no study has thoroughly examined how cooking affects the yields of ITCs from cruciferous vegetables. In this study, a high-performance liquid chromatography (HPLC)-based cyclocondensation assay was performed to examine the ITC yields from four major cruciferous vegetables (broccoli, cabbage, cauliflower, and kale) under six cooking conditions (stir-frying, steaming, microwaving, boiling, stewing, and chip-baking for kale only) and measured the level of ITCs under the raw condition for a comprehensive list of cruciferous vegetables and ITC-containing condiments. A wide range of ITC yields was found across vegetables and condiments. Cooking significantly altered the ITC yields, showing an averagely four-fold increase by lightly cooking (stir-frying, steaming, and microwaving) and a 58% decrease by heavily cooking (boiling, stewing, and chip-baking). These findings will provide the evidence-based cooking guidance on cruciferous vegetable consumption and help better estimate dietary ITC exposure in epidemiologic studies.

Genetic variants in anti-Müllerian hormone-related genes and breast cancer risk: results from the AMBER consortium

PURPOSE

Circulating anti-Müllerian hormone (AMH) levels are positively associated with time to menopause and breast cancer risk. We examined breast cancer associations with single nucleotide polymorphisms (SNPs) in the AMH gene or its receptor genes, ACVR1 and AMHR2, among African American women.

METHODS

In the AMBER consortium, we tested 65 candidate SNPs, and 1130 total variants, in or near AMH, ACVR1, and AMHR2 and breast cancer risk. Overall, 3649 cases and 4230 controls contributed to analyses. Odds ratios (OR) and 95% confidence intervals (CI) for breast cancer were calculated using multivariable logistic regression.

RESULTS

After correction for multiple comparisons (false-discovery rate of 5%), there were no statistically significant associations with breast cancer risk. Without correction for multiple testing, four candidate SNPs in ACVR1 and one near AMH were associated with breast cancer risk. In ACVR1, rs13395576[C] was associated with lower breast cancer risk overall (OR 0.84; 95% CI 0.72, 0.97) and for ER+ disease (OR 0.75; CI 0.62, 0.89) (p < 0.05). Rs1220110[A] and rs1220134[T] each had ORs of 0.89-0.90 for postmenopausal and ER+ breast cancer (p ≤ 0.03). Conversely, rs1682130[T] was associated with higher risk of ER+ breast cancer (OR 1.17; 95% CI 1.04, 1.32). Near AMH, rs6510652[T] had ORs of 0.85-0.90 for breast cancer overall and after menopause (p ≤ 0.02).

CONCLUSIONS

The present results, from a large study of African American women, provide limited support for an association between AMH-related polymorphisms and breast cancer risk and require replication in other studies.

Body fatness and mTOR pathway activation of breast cancer in the Women's Circle of Health Study

Energy imbalance has an important role in breast cancer prognosis. Hyperactive mechanistic Target of Rapamycin (mTOR) pathway is associated with breast tumor growth, but the extent to which body fatness is associated with mTOR pathway activities in breast cancer is unclear. We performed immunostaining for mTOR, phosphorylated (p)-mTOR, p-AKT, and p-p70S6K in tumor tissue from 590 women (464 African Americans/Blacks and 126 Whites) with newly diagnosed invasive breast cancer in the Women's Circle of Health Study. Anthropometric measures were taken by study staff, and body composition was measured by bioelectrical impedance analysis. Linear regressions were used to estimate percent differences in protein expression between categories of body mass index (BMI), waist circumference, waist/hip ratio, fat mass, fat mass index, and percent body fat. We observed that BMI ≥ 35.0 vs. <25 kg/m2 was associated with 108.3% (95% CI = 16.9%-270.9%) and 101.8% (95% CI = 17.0%-248.8%) higher expression in p-mTOR and normalized p-mTOR, i.e., p-mTOR/mTOR, respectively. Quartiles 4 vs. 1 of waist/hip ratio was associated with 41.8% (95% CI = 5.81%-89.9%) higher mTOR expression. Similar associations were observed for the body fat measurements, particularly in patients with estrogen receptor-negative (ER-) tumors, but not in those with ER+ tumors, although the differences in associations were not significant. This tumor-based study found positive associations between body fatness and mTOR pathway activation, evident by a p-mTOR expression, in breast cancer. Our findings suggest that mTOR inhibition can be a treatment strategy to prevent the recurrence of these tumors in obese individuals.

Abstract 4613: Cross-ancestry genome-wide association study identifies six new loci for breast cancer in women of African and european ancestry

Background: Over 180 genetic variants have been identified as risk loci for breast cancer. However, most loci were discovered using European ancestry populations. As some common susceptibility loci are shared across populations, we aim to discover new risk loci for breast cancer using a cross-ancestry genome-wide association study (GWAS) approach.

Methods: Data from five GWAS studies in women of African ancestry with a combined sample size of 9241 cases and 10192 controls were used to generate pooled breast cancer risk estimates in a fixed effect meta-analysis, and this served as the discovery dataset. Summary statistics from the GWAS conducted in European ancestry populations (Breast Cancer Association Consortium, 122977 cases and 105974 controls) served as the validation dataset. The variants that were associated with breast cancer risk at P &lt; 0.01 in the GWAS of African ancestry were meta-analyzed with the GWAS in European ancestry. A locus was considered novel if the lead index variant was genome-wide significant (5 × 10−8) in the cross-ancestry meta-analysis and &gt;500kb away from known breast cancer risk loci. Conditional on the lead index variants, we searched for additional signals in each locus using multivariable logistic regression. Analyses were done separately for ER-positive, ER-negative and overall breast cancer risk.

Results: We discovered four novel loci for overall breast cancer risk (1p13.3, 5q31.1, 15q24, and 15q26.3) and two novel loci for ER-negative breast cancer (1q41 and 7q11.23) at the genome-wide significance level of P &lt; 5 × 10−8. Three index single nucleotide polymorphism (SNPs) lie within introns of genes (KCNK2, C5orf56, and SIN3A) and the other index SNPs are located in intergenic regions (close to GSTM4 and AMPD2, CASTOR2, and the antisense DNA RP11-168G16.2). The direction of the associations was consistent between the GWASs of African and European descendants. At the 15q24 locus, we found an additional SNP (in the intron of the SCAMP2 gene) to be independently associated with overall breast cancer risk.

Conclusions: We have identified six new risk loci that may contribute to better prediction of breast cancer risk in African ancestry populations and provide new insights into mechanisms of breast cancer carcinogenesis. Replication of these loci in multiple populations and functional studies can help to identify causal variants.

Citation Format: Babatunde Adedokun, Zhaohui Du, Guimin Gao, Thomas Ahearn, Kathryn L. Lunetta, Gary Zirpoli, Jonine Figueroa, Esther M. John, Leslie Bernstein, Wei Zheng, Jennifer J. Hu, Regina G. Ziegler, Sarah Nyante, Elisa V. Bandera, Sue A. Ingles, Michael F. Press, Sandra L. Deming, Jorge L. Rodriguez-Gil, Song Yao, Temidayo O. Ogundiran, Oladosu Ojengbede, William Blot, Melissa Troester, Katherine L. Nathanson, Anselm Hennis, Barbara Nemesure, Stefan Ambs, Lara E. Sucheston-Campbell, Jeannette T. Bensen, Stephen J. Chanock, Andrew F. Olshan, Christine B. Ambrosone, David V. Conti, Olufunmilayo I. Olopade, Montserrat Garcia-Closas, Julie R. Palmer, Christopher A. Haiman, Dezheng Huo. Cross-ancestry genome-wide association study identifies six new loci for breast cancer in women of African and european 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 4613.

Abstract 2320: Evaluating a polygenic risk score for breast cancer in women of African ancestry

Background: A polygenic risk score (PRS) for breast cancer including 313 common variants developed by the Breast Cancer Association Consortium (BCAC) has been demonstrated to identify women who are at high risk of developing breast cancer [odds ratio (OR 95%CI) = 1.61 (1.57-1.65) per SD] in women of European ancestry. In the present study, we examined the performance of the 313-variant PRS and a PRS including 179 variants reaching genome-wide significance in previous genome-wide association studies (GWAS), in women of African ancestry.

Methods: We assembled genotype data for women of African ancestry from 28 breast cancer studies, including a total of 9,241 cases and 10,193 controls. We constructed the 179-variant and 313-variant PRSs with relative risk weights for each variant estimated in women of European ancestry in BCAC. The associations between the two PRSs and overall, ER+ and ER- breast cancer risk were estimated using logistic regression adjusting for age, study site and principal components. Discriminatory accuracy of the PRSs was evaluated using the receiver operating characteristic curve (AUROC). We then recalibrated the 179-variant PRS by replacing index variants with variants in each region that better captured risk in women of African ancestry and used relative risk weights estimated in women of African ancestry. We also assessed PRS performance by age (&lt;55 versus ≥ 55 years).

Results: Both the 179 and 313- variant PRSs were significantly associated with overall, ER+ and ER- breast cancer risk, with odds ratios (OR) per standard deviation of 1.21~1.37 and AUROCs ranging from 0.57 to 0.59. The 179-variant PRS outperformed in ER- cancer [1.31(1.24,1.37) per SD] while the 313-SNP PRS was better for overall [1.27(1.23,1.31) per SD] and ER+ cancer [1.37(1.32,1.43) per SD]. For overall breast cancer, compared to women with average risk (40th-60th PRS percentiles), women in the top decile of PRS had a 1.54 (95% CI: 1.38, 1.72)-fold increased risk. The performance of the recalibrated 179-variant PRS was not improved (average AUROC=0.56). The PRS ORs did not differ significantly across age strata (P-value for age interaction = 0.63).

Conclusion: Our study shows that both 179 and 313 variant PRS stratify breast cancer risk in women of African ancestry, with attenuated performance compared to that reported in European and in Latina populations. Future work is needed to improve breast cancer risk stratification for women of African ancestry.

Citation Format: Zhaohui Du, Guimin Gao, Babatunde Adedokun, Thomas Ahearn, Kathryn L. Lunetta, Gary Zirpoli, Melissa Troester, Edward A. Ruiz-Narváez, Stephen Haddad, Jonine Figueroa, Esther M. John, Leslie Bernstein, Wei Zheng, Jennifer J. Hu, Regina G. Ziegler, Sarah Nyante, Elisa V. Bandera, Sue A. Ingles, Michael F. Press, Sandra L. Deming, Jorge L. Rodriguez-Gil, Song Yao, Temidayo O. Ogundiran, Oladosu A. Ojengbede, William Blot, Katherine L. Nathanson, Anselm Hennis, Barbara Nemesure, Stefan Ambs, Lara E. Sucheston-Campbell, Jeannette T. Bensen, Stephen J. Chanock, Andrew F. Olshan, Christine B. Ambrosone, David V. Conti, Olufunmilayo I. Olopade, Julie R. Palmer, Montserrat Garcia-Closas, Dezheng Huo, Christopher A. Haiman. Evaluating a polygenic risk score for breast cancer 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 2320.

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

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 &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 &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 &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 &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 &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.

Relationships between Breast Feeding and Breast Cancer Subtypes: Lessons Learned from Studies in Humans and in Mice

There are differential risk relationships between parity and breast cancer according to estrogen receptor (ER) status, with an increased risk of ER^- disease reduced by breastfeeding. This may be particularly relevant for understanding the higher incidence of ER^- tumors in Black women, who are more likely to be parous and less likely to breastfeed than other U.S. groups. Potential mechanisms for these relationships may include effects of disordered breast involution on inflammatory milieu in the breast as well as epigenetic reprogramming in the mammary gland, which can affect cell fate decisions in progenitor cell pools. In normal breast tissue, parity has been associated with hypermethylation of FOXA1, a pioneer transcription factor that promotes the luminal phenotype in luminal progenitors, while repressing the basal phenotype. In breast tumors, relationships between FOXA1 methylation and parity were strongest among women who did not breastfeed. Here, we summarize the epidemiologic literature regarding parity, breastfeeding, and breast cancer subtypes, and review potential mechanisms whereby these factors may influence breast carcinogenesis, with a focus on effects on progenitor cell pools in the mammary gland.

Germline HOXB13 mutations p.G84E and p.R217C do not confer an increased breast cancer risk

In breast cancer, high levels of homeobox protein Hox-B13 (HOXB13) have been associated with disease progression of ER-positive breast cancer patients and resistance to tamoxifen treatment. Since HOXB13 p.G84E is a prostate cancer risk allele, we evaluated the association between HOXB13 germline mutations and breast cancer risk in a previous study consisting of 3,270 familial non-BRCA1/2 breast cancer cases and 2,327 controls from the Netherlands. Although both recurrent HOXB13 mutations p.G84E and p.R217C were not associated with breast cancer risk, the risk estimation for p.R217C was not very precise. To provide more conclusive evidence regarding the role of HOXB13 in breast cancer susceptibility, we here evaluated the association between HOXB13 mutations and increased breast cancer risk within 81 studies of the international Breast Cancer Association Consortium containing 68,521 invasive breast cancer patients and 54,865 controls. Both HOXB13 p.G84E and p.R217C did not associate with the development of breast cancer in European women, neither in the overall analysis (OR = 1.035, 95% CI = 0.859-1.246, P = 0.718 and OR = 0.798, 95% CI = 0.482-1.322, P = 0.381 respectively), nor in specific high-risk subgroups or breast cancer subtypes. Thus, although involved in breast cancer progression, HOXB13 is not a material breast cancer susceptibility gene.

Racial differences in CD8+ T cell infiltration in breast tumors from Black and White women

Background

African American/Black women with breast cancer have poorer survival than White women, and this disparity persists even after adjusting for non-biological factors. Differences in tumor immune biology have been reported between Black and White women, and the tumor immune milieu could potentially drive racial differences in breast cancer etiology and outcome.

Methods

We examined the association of CD8⁺ cytotoxic T cells with clinical-pathological variables in the Women’s Circle of Health Study (WCHS) population of predominantly Black breast cancer patients. We evaluated 688 invasive breast tumor samples (550 Black, 138 White) using immunohistochemical staining of tissue microarray slides. CD8⁺ T cells were scored for each patient tumor sample with digital image analysis.

Results

Black women had a significantly higher percentage of high-grade, estrogen receptor (ER)-negative, and triple-negative tumors than White women and significantly higher CD8⁺ T cell density (median 87.6/mm² vs. 53.1/mm²; p < 0.001). Within the overall population and in the population of Black women only, CD8⁺ T cell density was significantly higher in younger patients and patients with high-grade and ER/PR-negative tumors. No significant associations were observed between CD8⁺ T cell density and overall survival or breast cancer-specific survival in the overall population, or when Black patients were analyzed as a separate group. However, when stratified by subtype, Black women with triple-negative breast cancer and high CD8⁺ T cell density showed a trend towards better overall survival in comparison with patients with low CD8⁺ T cell density (HR = 0.51; 95% CI 0.25–1.04).

Conclusions

Our data raise the possibility that distinct mechanisms of immune cell action may occur in different racial groups.

Abstract D101: Breast cancer in Black women: Do risk factors differ for those who have a family history of breast cancer?

Background: Women who have at least one first-degree relative diagnosed with breast cancer have an almost two-fold risk of developing breast cancer themselves. Therefore, there is particular interest in identifying modifiable factors that can reduce risk. To date, most studies of breast cancer risk in women with a family history of breast cancer have focused on White women. Methods: We pooled questionnaire data on Black women from three case-control studies (Women’s Contraceptive and Reproductive Experiences, Carolina Breast Cancer Study, and Women’s Circle of Health Study) and nested case-control data from the prospective Black Women’s Health Study for an analytic sample of 5,015 invasive breast cancer cases and 15,354 controls; 15.9% of cases and 9.4% of controls reported a first-degree family history of breast cancer (“family history”). We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for risk of breast cancer overall, and by estrogen receptor (ER) status, within strata of family history. All models were adjusted for age and study. Additional covariates were body mass index (recent and at age 18), adult height, smoking, alcohol consumption, parity, breastfeeding, age at first birth, age at menarche, interval between menarche and first birth, age at menopause, and history of benign breast disease. Results: ORs were consistent among women with and without a family history for most factors. However, associations of parity and breastfeeding with risk of ER negative breast cancer were stronger among women with a positive family history: the OR for ever parous vs. nulliparous was 1.63 (1.11-2.39) among women with a family history and 1.31 (1.13-1.53) among those without. In both groups, the elevated OR associated with parity was reduced if the women had breastfed at least one child. The ORs for ER negative breast cancer associated with parity without breastfeeding were 1.86 (1.25-2.77) and 1.43 (1.22-1.67), among women with and without a family history of breast cancer, respectively (p-interaction &gt;0.05). Additional control for other reproductive factors did not materially change the estimates. Breastfeeding was not associated with risk of ER positive breast cancer in either group. Conclusion: As has been shown previously, parous women were found to be at increased risk of ER negative breast cancer, with the increase attenuated by breastfeeding. Stratification by family history of breast cancer indicated that the associations may be stronger among women with a first-degree family history, although interactions were not statistically significant. Findings from the present study demonstrate that Black women who already have a higher than average baseline risk of ER negative breast cancer due to their familial history may favorably modify their risk by breastfeeding.

Citation Format: Gary R Zirpoli, Traci N Bethea, Leslie Bernstein, Melissa A Troester, Christine B Ambrosone, Julie R Palmer. Breast cancer in Black women: Do risk factors differ for those who have a family history of breast cancer? [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 D101.

Abstract C063: Associations of leptin and leptin receptor protein and gene expression with breast cancer clinicopathologic features

The adipokine, leptin (LEP) and its receptor (leptin receptor, LEPR), are hypothesized to play a role in breast cancer (BrCa) outcomes disparities. The objective of this study was to address the gaps in knowledge regarding the epidemiologic associations of LEP and LEPR protein and gene expression with breast cancer clinicopathologic features (namely, estrogen receptor [ER] status, and tumor grade, stage, size, and subtype). In the Women's Circle of Health Study, we used immunohistochemistry to assess protein expression in breast tumor tissue microarrays among a sample of 711 early stage BrCa cases. LEP and LEPR protein expression was scored semiquantitatively by a board-certified pathologist and we used NanoString digital, multiplexed assays to quantitatively assess gene expression of these biomarkers. Multivariable-adjusted logistic regression models were used to examine the associations of interest. Compared to ER+, LEP protein expression was lower (OR 0.54, 95% CI 0.30, 1.00), and LEPR protein (OR 3.95, 95% CI 2.02, 7.71) and gene expression (OR 1.003, 95% CI 1.001, 1.005) were higher among ER- BrCa cases. Compared to well/moderately differentiated tumors, LEPR protein (OR 2.46, 95% CI 1.40, 4.31) and gene expression (OR 1.002, 95% CI 1.000, 1.003) were higher among poorly differentiated tumors. Compared to luminal A, LEP protein expression was higher among non-luminal HER2-expressing (OR 3.34, 95% CI 1.20, 9.32) and TNBC subtypes (OR 2.02, 95% CI 1.00, 4.08), LEPR protein expression was lower among non-luminal HER2-expressing (OR 0.39, 95% CI 0.16, 0.94) and TNBC (OR 0.28, 95% CI 0.13, 0.57), and LEPR gene expression was lower in TNBC (OR 0.997, 95% CI 0.995, 0.999). LEP gene expression and LEPR protein and gene expression were inversely associated with tumor size (P-values &lt;0.05). No major associations were observed between LEP and LEPR expression profiles and tumor stage. These findings suggest that LEP and LEPR protein and gene expression in the breast tumor microenvironment may serve as biomarkers contributing to interindividual differences in BrCa prognostic indicators and are important for understanding tumor heterogeneity and outcomes disparities.

Funding: This study was supported by grants from the National Cancer Institute (K01CA193527, P01CA151135, R01CA100598, R01CA185623). Tumor samples were received, processed and tracked under the auspices of the Roswell Park Comprehensive Cancer Center DataBank and BioRepository Shared Resource, supported by P30CA16056 with support from the Breast Cancer Research Foundation to CBA. This work was also supported by the Biomedical Informatics and the Biospecimen Repository and Histopathology Service shared resources of Rutgers Cancer Institute of New Jersey, supported by P30CA072720.

Citation Format: Adana A.M. Llanos, Baichen Xu, Bo Qin, Wenjin Chen, Marina A. Chekmareva, Lei Cong, Chi-Chen Hong, Song Yao, Christine B. Ambrosone, Elisa V. Bandera, Kitaw Demissie. Associations of leptin and leptin receptor protein and gene expression with breast cancer clinicopathologic features [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C063.

Abstract C063: Impact of neighborhood socioeconomic status on breast cancer subtypes among Black women

Background: Compared to White women, African American/Black women are more likely to develop triple-negative breast cancer (TNBC), an aggressive breast cancer subtype. While many studies have examined individual-level socioeconomic status (SES) as a major social determinant of more aggressive breast tumor phenotypes, the impact of neighborhood-level SES (nSES) on breast cancer is not well understood, particularly among Blacks. Objective: To evaluate the impact of nSES on breast cancer subtypes among Black women with breast cancer. Methods: We evaluated the association of interest among 1,220 Black women with invasive breast cancer from 2006 to 2018 enrolled from 10 counties of New Jersey in the Women’s Circle of Health Study (WCHS). Residential address at diagnosis was geocoded to the census tract-level. Neighborhood SES was measured using the NCI’s census tract-level SES index, a time-dependent score constructed by a factor analysis of seven variables measuring different aspects of census tract SES (education index, percent unemployed, percent working class, median household income, percent below 150% of poverty line, median house value, and median rent). In a case-only analysis, we used multilevel multinomial logistic regressions to estimate nSES in relation to breast cancer subtype (TNBC, HER2-enriched, Luminal B vs. Luminal A). Models were adjusted for individual-level SES variables, body mass index and reproductive factors, and census tract-level percentage of Black residents. We tested whether the associations were modified by percentage of Black residents and participant’s education. Results: Higher nSES was found to predict a lower risk of TNBC. Compared to tertile 1 (lowest nSES score), the odds ratio (OR) was 0.91 (95% CI: 0.65, 1.29) for tertile 2 and 0.52 (95% CI: 0.34, 0.79) for tertile 3 (highest nSES score; p-trend: 0.001). Higher nSES was borderline significantly associated with a lower risk of Luminal B (OR: 0.61 comparing highest vs. lowest nSES tertile; 95% CI: 0.36, 1.03; p-trend: 0.055). The inverse association between nSES and TNBC was observed only among Black women living in census tracts with lower proportion of Black residents (p-for-interaction=0.08). Compared to the lowest nSES tertile, OR was 0.38 (95% CI: 0.21, 0.68) for the highest tertile (p-trend: &lt;0.001). There was a suggestion that the inverse relationship of nSES with TNBC was also more pronounced among women who had relatively lower levels of education. Conclusion: Neighborhood socioeconomic environment may influence the development of TNBC among Black women, which might be buffered by some contextual factors in areas with more Black residents. Further investigation to elucidate these factors is needed.

Citation Format: Bo Qin, Adana A.M. Llanos, Riddhi Babel, Jesse J. Plascak, Karen Pawlish, Christine B. Ambrosone, Kitaw Demissie, Chi-Chen Hong, Elisa V. Bandera. Impact of neighborhood socioeconomic status on breast cancer subtypes among Black women [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 C063.

Abstract IA26: Breast tumor microenvironment in black women: A distinct signature of CD8+ T-cell exhaustion

Background: Blacks tend to have a stronger inflammatory immune response than Whites. We hypothesized that racial differences in host immunity also manifest in the tumor microenvironment (TME), constituting part of a distinct tumor biology underlying more aggressive breast cancer and higher mortality in Black women.

Patients and Methods: Pathologic and gene expression profiling approaches were used for comprehensively characterizing infiltrating immune cells in breast TME from 1,315 patients from the Women’s Circle of Health Study (WCHS). Racial differences in tumor immune phenotypes were compared, with results validated in data from The Cancer Genome Atlas (TCGA). Prognostic associations of immune phenotypes were assessed in WCHS, TCGA and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) cohorts.

Results: We found marked and consistent differences in tumor immune responses between Black and White patients. Not only did tumors from Blacks display a stronger overall immune presence, but the composition and quality of immune infiltrates differed, independent of tumor subtypes. Black patients had a stronger humoral immunity response, and further, a more exhausted CD8+ T-cell profile featuring the coexpression of PD-1, LAG3, and CTLA4. A signature indicating a higher ratio of exhausted CD8+ T cells to total CD8+ T cells (ExCD8-r) was consistently associated with poorer survival, particularly among hormone receptor-positive patients. Combinations of the absolute fraction of CD8+ T cells and ExCD8-r signature identified the CD8-low/ExCD8-r-high subgroup, the most prevalent among Blacks, as having the worst survival.

Conclusions: Our findings of a distinct exhausted CD8+ T-cell signature in Black breast cancer patients indicates an immunobiologic basis for their more aggressive disease, and also a rationale for the use of immune checkpoint inhibitors targeting the exhaustion phenotype.

Citation Format: Song Yao, Ting-Yuan Cheng, Ahmed Elkhanany, Li Yan, Angela Omilian, Scott I. Abrams, Sharon Evans, Chi-Chen Hong, Qianya Qi, Warren Davis, Song Liu, Elisa V. Bandera, Kunle Odunsi, Kazuaki Takabe, Thaer Khoury, Christine B. Ambrosone. Breast tumor microenvironment in black women: A distinct signature of CD8+ T-cell exhaustion [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 IA26.

Immunological changes with perception of cold in breast cancer (BC) patients

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Background: Tumor-bearing mice “feel colder” than non-tumor bearing mice and prefer to be at thermoneutral temperatures. Cold stress results in immunosuppressive tumor microenvironment [decrease in CD8+T-cells, increase in myeloid derived suppressor cells and T-regulatory cells]. Cytokines play a significant role in modulating these immune cells. Breast cancer (BC) patients frequently report feeling excessively cold under ambient temperature. We examined the association between cytokine levels and thermal discomfort symptoms in BC patients in the Women’s Health After Breast Cancer (ABC) Study treated at Roswell Park Comprehensive Cancer Center. Methods: 424 stage I-III BC patients were identified. Standard demographics, body mass index (BMI), race, grade, histological subtype, tumor size, stage, nodal status, treatment received, and menopausal status were recorded. Peripheral blood was prospectively collected at diagnosis and one year post diagnosis and analyzed for a panel of 27 cytokines. Patients completed a questionnaire reporting symptom of “feeling cold when others are fine” using a Likert scale one year post BC diagnosis. Relationships between cytokines levels as tertiles and symptoms of “feeling cold” were evaluated using logistic regression. Change in cytokine levels from the time of BC diagnosis to one year post were also evaluated [ > 20% decrease, no change (-20 to +20%), and > 20% increase]. Results: Overall, 195/424 (46%) patients reported “feeling cold”. There were no differences in patient and tumor characteristics between patients who reported “feeling cold” vs “not cold.” Interestingly, 53.4% patients on chemotherapy reported “feeling cold” (p < 0.05). At baseline, higher IL-17E and IL-6 were associated with decreased perception of feeling cold (p < 0.05, p < 0.01). At one year post diagnosis, higher TNF-β was associated with decreased perception of feeling cold (p < 0.05). Changes in IL-22 and IL-33 were associated with increased perception of feeling cold (p < 0.05, p < 0.05). Multivariate model adjusted for age, race, BMI, histological subtype, stage, grade, treatment and menopausal status showed a trend towards decreased cold perception with higher IL-6 but was not statistically significant. Conclusions: We observe significant differences in pro-tumorigenic IL-6 and anti-tumorigenic IL-17E & TNF-β cytokines in BC patients reporting thermal discomfort. This suggests avenues for using thermal therapies to modulate inflammatory cytokine production in breast cancer.

Role of CD8+ T-cell infiltration in breast tumors of Black women compared to White women

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Background: Literature regarding racial differences in tumor immune responses in breast cancer remains sparse. To address this research gap, we assessed CD8+ T-cells in breast tumor samples from the Women’s Circle of Health Study (WCHS) population of predominantly Black breast cancer patients. We characterized and compared the density of CD8+ T cells, their prognostic value and their association with pharmacologic beta-blockers. Prior studies suggest that reducing adrenergic signaling through beta blockers can stimulate CD8+ T-cells. Methods: Tumor-infiltrating CD8+ T-cells were assessed by IHC staining of tissue microarray cores from 688 breast cancer patients, including 550 Blacks and 138 Whites. CD8+ T cells were scored with digital image analysis. Comparisons of demographic and clinical variables (including CD8+ T cell density) were made using the Mann-Whitney U or Kruskal-Wallis and Fisher’s exact tests. Associations with overall survival (OS) and disease-specific (DSS) survival were evaluated using the log-rank test of Cox regression. Analyses were performed in the overall sample and by disease sub-type. Results: Higher CD8+ T cell density was seen in Black women compared to White, with mean values of 756.2/mm2 and 292.4/mm2 respectively (p < 0.001). Within the overall population and in black women, CD8+ T cell density was significantly higher in younger patients, patients with high grade, and ER negative tumors. No significant associations were observed between CD8+ T cell density and OS or DSS. However, when stratified by subtype, Black patients with triple negative breast cancer and high CD8+ T cell density showed a trend towards improved OS in comparison to patients with low CD8+ T cell density (p = 0.065). 170 patients with information on beta blocker usage were analyzed. No significant associations were noted between CD8+ T cell density and beta blocker use. Conclusions: We observe a significantly higher CD8+ T cell density in Blacks compared to Whites, but this does not confer a survival advantage. Additionally, beta-blockers did not seem to enhance CD8+ T cell infiltration in tumors from Black patients. Our data raise the possibility that distinct mechanisms of immune cell action may occur in different racial groups. Future studies are needed to determine the functional properties of CD8+ T cells in Black women and to characterize additional immune cell subtypes that may also play a role.

The Association of Modifiable Breast Cancer Risk Factors and Somatic Genomic Alterations in Breast Tumors: The Cancer Genome Atlas Network

BACKGROUND

The link between modifiable breast cancer risk factors and tumor genomic alterations remains largely unexplored. We evaluated the association of prediagnostic body mass index (BMI), cigarette smoking, and alcohol consumption with somatic copy number variation (SCNV), total somatic mutation burden (TSMB), seven single base substitution (SBS) signatures (SBS1, SBS2, SBS3, SBS5, SBS13, SBS29, and SBS30), and nine driver mutations (CDH1, GATA3, KMT2C, MAP2K4, MAP3K1, NCOR1, PIK3CA, RUNX1, and TP53) in a subset of The Cancer Genome Atlas (TCGA).

METHODS

Clinical and genomic data were retrieved from the TCGA database. Risk factor information was collected from four TCGA sites (n = 219 women), including BMI (1 year before diagnosis), cigarette smoking (smokers/nonsmokers), and alcohol consumption (current drinkers/nondrinkers). Multivariable regression analyses were conducted in all tumors and stratified according to estrogen receptor (ER) status.

RESULTS

Increasing BMI was associated with increasing SCNV in all women (P = 0.039) and among women with ER- tumors (P = 0.031). Smokers had higher SCNV and TSMB versus nonsmokers (P < 0.05 all women). Alcohol drinkers had higher SCNV versus nondrinkers (P < 0.05 all women and among women with ER+ tumors). SBS3 (defective homologous recombination-based repair) was exclusively found in alcohol drinkers with ER- disease. GATA3 mutation was more likely to occur in women with higher BMI. No association was significant after multiple testing correction.

CONCLUSIONS

This study provides preliminary evidence that BMI, cigarette smoking, and alcohol consumption can influence breast tumor biology, in particular, DNA alterations.

IMPACT

This study demonstrates a link between modifiable breast cancer risk factors and tumor genomic alterations.

Abstract P5-08-07: Tobacco use, alcohol consumption, and breast cancer somatic genomic alterations

Background: Understanding the molecular influence of epidemiological risk factors can provide insights into breast cancer etiology and progression, and lead to better prevention efforts and treatment guidelines. The link between modifiable breast cancer risk factors and tumor genomic alterations remains unexplored. This study evaluated the association of tobacco use and alcohol consumption with somatic copy number variation (SCNV), total somatic mutation burden (TSMB), seven single base substitution (SBS) signatures (SBS1, SBS2, SBS3, SBS5, SBS13, SBS29, and SBS30) (1-3), and nine breast cancer driver mutations (CDH1, GATA3, KMT2C, MAP2K4, MAP3K1, NCOR1, PIK3CA, RUNX1, and TP53) (4,5), in a subset of The Cancer Genome Atlas (TCGA).

Method: Clinical and genomic data were retrieved from the TCGA database, and breast cancer risk factor information was collected from four TCGA sites; in all, 219 female breast cancer cases were included. Pre-diagnostic tobacco use was defined as never or ever; alcohol consumption was defined as drinkers or non-drinkers. Total SCNV was obtained by summing all segments with ≥|0.2|. TSMB was calculated by summing all significant mutations for each case. SBS signatures were computed using whole exome sequencing data. Analyses were conducted in all tumors (i.e., pooled) and by stratifying according to estrogen receptor (ER) status using multivariate regression, adjusting for co-variables.

Results: Tobacco users had higher TSMB compared to non-users (p&lt;0.05 all tumors). Alcohol drinkers had higher SCNV compared to non-drinkers (p&lt;0.05 all tumors and among ER+ tumors). Tobacco use was not associated with any SBS signature. SBS3 signature (defective homologous recombination-based repair) was exclusively found in alcohol drinkers with ER- disease. No breast cancer driver mutation was associated with tobacco use or alcohol consumption.

Conclusion: This study provides preliminary evidence that tobacco use and alcohol consumption can influence breast tumor biology, in particular, DNA alterations. Future larger epidemiological studies are required to confirm these findings.

References

1. Vineis P, et al. Mutational signatures associated with tobacco smoking in human cancer. Science. 2016;354(6312):618-22.

2. Alexandrov LB, et al. Clock-like mutational processes in human somatic cells. Nat Genet. 2015;47(12):1402-7.

3. Petljak M, Alexandrov LB. Understanding mutagenesis through delineation of mutational signatures in human cancer. Carcinogenesis. 2016;37(6):531-40.

4. Heng YJ, et al. The molecular basis of breast cancer pathologic phenotypes. J Pathol. 2017 Nov;241(3):375-91.

5. Ciriello G, et al. Comprehensive Molecular Portraits of Invasive Lobular Breast Cancer. Cell. 2015 Oct 10;163(2):506-19.

Citation Format: Yujing J Heng, Susan E Hankinson, Jun Wang, Ludmil B Alexandrov, Christine B Ambrosone, Victor Piana de Andrade, Adam M Brufsky, Fergus J Couch, Tari A King, Francesmary Modugno, Celine M Vachon, A. Heather Eliassen, Rulla M Tamimi, Peter Kraft. Tobacco use, alcohol consumption, and breast cancer somatic genomic alterations [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-08-07.

Abstract PD3-01: Population-based breast cancer risk estimates for predisposition gene mutations: Results from the CARRIERS study

Germline mutations in several cancer predisposition genes included in hereditary multigene testing panels have been associated with increased breast cancer risk. However, estimates of breast cancer risks for each gene have in large part been derived from studies of high-risk populations enriched for family history of breast and ovarian cancer, young age of breast cancer diagnosis, or founder mutations. The breast cancer risks associated with mutations in many of these genes in the general population remain to be clearly defined. As clinical hereditary cancer genetic testing is already provided to many women at increased risk and may soon be offered to all breast cancer patients, population-based risk estimates associated with predisposition gene mutations will be needed for appropriate clinical management of mutation carriers. The “CAnceR RIsk Estimates Related to Susceptibility” (CARRIERS) consortium of 17 cohort-based case-control, population-based case-control, and family studies focused on estimation of population-based breast cancer risks and penetrance analysis for mutations in known and candidate breast cancer predisposition genes. Germline DNA from 39486 breast cancer cases and 35868 matched controls was subjected to dual bar-coded QIAseq multiplex amplification of 1733 target regions in 37 predisposition genes. Products from sets of 768 samples were pooled and sequenced in each lane of a HiSeq 4000 system. Mutations were called by GATK Haplotype Caller and Verdict. High quality sequence data was obtained for 99.3% of target regions. Here we report on results from 34741 population-based breast cancer cases and 32728 matched unaffected controls. The mean age of breast cancer diagnosis for cases was 61.2 years and mean age for controls was 61.1 years. Overall, 20.9% of cases and 14.3% of controls had a family history of breast cancer. Furthermore, 74.3% of cases and 75.8% of controls were non-Hispanic white, whereas 13.3% of cases and 15.3% of controls were African American. Among cases with tumor information available, 81.7% were ER-positive and 7.7% were triple negative breast cancers (TNBC). We assessed mutation frequencies in 24 genes including 12 established breast cancer predisposition genes (ATM, BARD1, BRCA1, BRCA2, CDH1, CHEK2, NF1, PALB2, PTEN, RAD51C, RAD51D, andTP53). The overall mutation frequency was 6.2% in cases and 2.7% in controls. Case-control association analysis after adjusting for study, age, family history of breast cancer, and race/ethnicity showed that BRCA1(OR=7.45; 95%CI:5.24-10.95) and BRCA2(OR=5.31; 95%CI:4.15-6.88) were associated with high risks of breast cancer in the general population. However, PALB2mutations were only associated with moderate risks (OR=3.63; 95%CI:2.57-5.26). ATMmutations conferred attenuated risks (OR=1.83; 95%CI:1.47-2.28) relative to studies of high-risk families or young onset breast cancers. NBNmutations were not associated with increased breast cancer risk. Mutations in BARD1, RAD51C, RAD51Dand XRCC2were specifically significantly associated with moderate risks of ER-negative breast cancer and TNBC, whereas mutations in ATM, CDH1and CHEK2were specifically significantly associated with ER-positive disease. On the basis of these findings age-related absolute breast cancer risks for commonly mutated genes were estimated. Overall, results from the CARRIERS study establish that mutations in predisposition genes are associated with lower risks of breast cancer in the general population than in enriched populations including high-risk families and young onset, bilateral, or multiple primary cases. We anticipate that the results from this study will inform cancer screening and other risk management strategies for women in the general population with mutations in predisposition genes.

Citation Format: Fergus J Couch, Chunling Hu, Steven N Hart, Rohan Gnanaolivu, Kun Y Lee, Jie Na, Chi Gao, Nicholas J Boddicker, Bruce Eckloff, Raed Samara, Josh Klebba, Christine B Ambrosone, Hoda Anton-Culver, Paul Auer, Leslie Bernstein, Mia M Gaudet, Christopher Haiman, Esther M John, Susan Neuhausen, Janet E Olson, Tuya Pal, Julie R Palmer, Dale P Sandler, Jack A Taylor, Amy Trentham-Dietz, Celine M Vachon, Clarice Weinberg, Song Yao, Jeffrey N Weitzel, David E Goldgar, Susan M Domchek, Katherine L Nathanson, Peter Kraft, Eric C Polley. Population-based breast cancer risk estimates for predisposition gene mutations: Results from the CARRIERS study [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr PD3-01.

Immunohistochemical analysis of adipokine and adipokine receptor expression in the breast tumor microenvironment: associations of lower leptin receptor expression with estrogen receptor-negative status and triple-negative subtype

BACKGROUND

The molecular mechanisms underlying the association between increased adiposity and aggressive breast cancer phenotypes remain unclear, but likely involve the adipokines, leptin (LEP) and adiponectin (ADIPOQ), and their receptors (LEPR, ADIPOR1, ADIPOR2).

METHODS

We used immunohistochemistry (IHC) to assess LEP, LEPR, ADIPOQ, ADIPOR1, and ADIPOR2 expression in breast tumor tissue microarrays among a sample of 720 women recently diagnosed with breast cancer (540 of whom self-identified as Black). We scored IHC expression quantitatively, using digital pathology analysis. We abstracted data on tumor grade, tumor size, tumor stage, lymph node status, Ki67, estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) from pathology records, and used ER, PR, and HER2 expression data to classify breast cancer subtype. We used multivariable mixed effects models to estimate associations of IHC expression with tumor clinicopathology, in the overall sample and separately among Blacks.

RESULTS

Larger proportions of Black than White women were overweight or obese and had more aggressive tumor features. Older age, Black race, postmenopausal status, and higher body mass index were associated with higher LEPR IHC expression. In multivariable models, lower LEPR IHC expression was associated with ER-negative status and triple-negative subtype (P < 0.0001) in the overall sample and among Black women only. LEP, ADIPOQ, ADIPOR1, and ADIPOR2 IHC expression were not significantly associated with breast tumor clinicopathology.

CONCLUSIONS

Lower LEPR IHC expression within the breast tumor microenvironment might contribute mechanistically to inter-individual variation in aggressive breast cancer clinicopathology, particularly ER-negative status and triple-negative subtype.

Intake of vitamin D and calcium, sun exposure, and risk of breast cancer subtypes among black women

BACKGROUND

The randomized placebo-controlled Vitamin D and Omega-3 Trial suggested a possible benefit of vitamin D on cancer incidence among black individuals. However, data are limited regarding the impact of vitamin D on breast cancer subtypes among African-American/black women, who tend to develop more aggressive forms of breast cancer.

OBJECTIVES

We hypothesize that more vitamin D exposure (through diet, supplements, and sunlight) and higher intake of calcium are associated with decreased risk of estrogen receptor (ER)+ and ER- breast cancer, and of triple-negative breast cancer (TNBC) among black women.

METHODS

This study was conducted among 1724 black cases and 1233 controls in the Women's Circle of Health Study (WCHS) and WCHS2. Polytomous logistic regressions were used to estimate ORs and 95% CIs of ER+ and ER- breast cancer; logistic regressions were used for TNBC. The ORs from each study were pooled using an inverse-variance-weighted random-effects model.

RESULTS

Dietary vitamin D and calcium intake were not associated with risk of breast cancer subtypes in the pooled analysis. For supplemental vitamin D, we observed possible inverse associations between intake of ≤800 IU/d (compared with nonuse) and risk of several subtypes, with effects that appeared strongest for TNBC (OR: 0.58; 95% CI: 0.35, 0.94); no association was found for >800 IU/d. More daylight hours spent outdoors in a year was associated with lower risk of ER+, ER-, and TNBC (e.g., highest compared with lowest quartile: TNBC OR: 0.53; 95% CI: 0.31, 0.91; P-trend = 0.02).

CONCLUSIONS

Moderate supplemental vitamin D intake was associated with decreased risk of TNBC, and increased sun exposure was associated with reduced risk of ER+, ER-, and TNBC among black women.