eQTL Set-Based Association Analysis Identifies Novel Susceptibility Loci for Barrett Esophagus and Esophageal Adenocarcinoma.

BACKGROUND: Over 20 susceptibility single-nucleotide polymorphisms (SNP) have been identified for esophageal adenocarcinoma (EAC) and its precursor, Barrett esophagus (BE), explaining a small portion of heritability. METHODS: Using genetic data from 4,323 BE and 4,116 EAC patients aggregated by international consortia including the Barrett's and Esophageal Adenocarcinoma Consortium (BEACON), we conducted a comprehensive transcriptome-wide association study (TWAS) for BE/EAC, leveraging Genotype Tissue Expression (GTEx) gene-expression data from six tissue types of plausible relevance to EAC etiology: mucosa and muscularis from the esophagus, gastroesophageal (GE) junction, stomach, whole blood, and visceral adipose. Two analytical approaches were taken: standard TWAS using the predicted gene expression from local expression quantitative trait loci (eQTL), and set-based SKAT association using selected eQTLs that predict the gene expression. RESULTS: Although the standard approach did not identify significant signals, the eQTL set-based approach identified eight novel associations, three of which were validated in independent external data (eQTL SNP sets for EXOC3, ZNF641, and HSP90AA1). CONCLUSIONS: This study identified novel genetic susceptibility loci for EAC and BE using an eQTL set-based genetic association approach. IMPACT: This study expanded the pool of genetic susceptibility loci for EAC and BE, suggesting the potential of the eQTL set-based genetic association approach as an alternative method for TWAS analysis.

Circulating MicroRNAs in Relation to Esophageal Adenocarcinoma Diagnosis and Survival.

BACKGROUND AND AIMS: Tissue miRNA can discriminate between esophageal adenocarcinoma (EA) and normal epithelium. However, no studies have examined a comprehensive panel of circulating miRNAs in relation to EA diagnosis and survival. METHODS: We used all 62 EA cases from the US Multi-Center case-control study with available serum matched 1:1 to controls. Cases were followed for vital status. MiRNAs (n = 2064) were assessed using the HTG EdgeSeq miRNA Whole Transcriptome Assay. Differential expression analysis of miRNAs in relation to case-control status was conducted. In cases, Cox regression models were fit to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause mortality. P values were adjusted using the Benjamini-Hochberg (BH) procedure for false discovery rate control. Predictive performance was assessed using cross-validation. RESULTS: Sixty-eight distinct miRNAs were significantly upregulated between cases and controls (e.g., miR-1255b-2-3p fold change = 1.74, BH-adjusted P = 0.01). Assessing the predictive performance of these significantly upregulated miRNAs yielded 60% sensitivity, 65% specificity, and 0.62 AUC. miR-4253 and miR-1238-5p were associated with risk of mortality after EA diagnosis (HR = 4.85, 95% CI: 2.30-10.23, BH-adjusted P = 0.04 and HR = 3.81, 95% CI: 2.02-7.19, BH-adjusted P = 0.04, respectively). CONCLUSIONS: While they require replication, these findings suggest that circulating miRNAs may be associated with EA diagnosis and survival.

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.

Sex-Specific Genetic Associations for Barrett's Esophagus and Esophageal Adenocarcinoma.

BACKGROUND & AIMS: Esophageal adenocarcinoma (EA) and its premalignant lesion, Barrett's esophagus (BE), are characterized by a strong and yet unexplained male predominance (with a male-to-female ratio in EA incidence of up to 6:1). Genome-wide association studies (GWAS) have identified more than 20 susceptibility loci for these conditions. However, potential sex differences in genetic associations with BE/EA remain largely unexplored. METHODS: Given strong genetic overlap, BE and EA cases were combined into a single case group for analysis. These were compared with population-based controls. We performed sex-specific GWAS of BE/EA in 3 separate studies and then used fixed-effects meta-analysis to provide summary estimates for >9 million variants for male and female individuals. A series of downstream analyses were conducted separately in male and female individuals to identify genes associated with BE/EA and the genetic correlations between BE/EA and other traits. RESULTS: We included 6758 male BE/EA cases, 7489 male controls, 1670 female BE/EA cases, and 6174 female controls. After Bonferroni correction, our meta-analysis of sex-specific GWAS identified 1 variant at chromosome 6q11.1 (rs112894788, KHDRBS2-MTRNR2L9, PBONF = .039) that was statistically significantly associated with BE/EA risk in male individuals only, and 1 variant at chromosome 8p23.1 (rs13259457, PRSS55-RP1L1, PBONF = 0.057) associated, at borderline significance, with BE/EA risk in female individuals only. We also observed strong genetic correlations of BE/EA with gastroesophageal reflux disease in male individuals and obesity in female individuals. CONCLUSIONS: The identified novel sex-specific variants associated with BE/EA could improve the understanding of the genetic architecture of the disease and the reasons for the male predominance.

Menopausal hormone therapy use and long-term all-cause and cause-specific mortality in the Long Island Breast Cancer Study Project.

Previous studies have observed a reduced mortality risk associated with menopausal hormone therapy (MHT) use among breast cancer survivors. We sought to clarify whether such association could be explained by tumor heterogeneity, specific causes of death, confounding from comorbidities or health behaviors, and a comparison group of women without breast cancer. We interviewed 1508 women newly diagnosed with first primary breast cancer in 1996 to 1997 (~3 months after diagnosis), and 1556 age-matched women without breast cancer, about MHT use history. The National Death Index was used to ascertain vital status after a median of 17.6 years of follow-up (N = 597 deaths for breast cancer subjects). Multivariable-adjusted Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (95%CIs) for all-cause mortality, and cause-specific HR (cHR) for breast cancer and cardiovascular disease (CVD). The Fine-Gray model was used to account for competing causes of death. Among women with breast cancer, ever vs never MHT use was inversely associated with all-cause (HR = 0.77, 95%CI = 0.62-0.95), breast cancer-specific (cHR = 0.69, 95%CI = 0.48-0.98), and CVD-specific mortality (cHR = 0.57, 95%CI = 0.38-0.85). Difference of the association was observed in breast cancer-specific mortality according to hormone receptor status (negative tumors: cHR = 0.44, 95%CI = 0.19-1.01; positive tumors: cHR = 0.96, 95%CI = 0.60-1.53). Among the comparison group, we observed similar, but more modest inverse associations for all-cause and CVD-specific mortality. MHT use was inversely associated with mortality after breast cancer, even after accounting for competing causes of death and multiple confounders, and was evident among women without breast cancer. Potential heterogeneity by hormone receptor status requires more study.

Urinary Estrogen Metabolites and Long-Term Mortality Following Breast Cancer.

BACKGROUND: Estrogen metabolite concentrations of 2-hydroxyestrone (2-OHE1) and 16-hydroxyestrone (16-OHE1) may be associated with breast carcinogenesis. However, no study has investigated their possible impact on mortality after breast cancer. METHODS: This population-based study was initiated in 1996-1997 with spot urine samples obtained shortly after diagnosis (mean = 96 days) from 683 women newly diagnosed with first primary breast cancer and 434 age-matched women without breast cancer. We measured urinary concentrations of 2-OHE1 and 16-OHE1 using an enzyme-linked immunoassay. Vital status was determined via the National Death Index (n = 244 deaths after a median of 17.7 years of follow-up). We used multivariable-adjusted Cox proportional hazards to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the estrogen metabolites-mortality association. We evaluated effect modification using likelihood ratio tests. All statistical tests were two-sided. RESULTS: Urinary concentrations of the 2-OHE1 to 16-OHE1 ratio (>median of 1.8 vs ≤median) were inversely associated with all-cause mortality (HR = 0.74, 95% CI = 0.56 to 0.98) among women with breast cancer. Reduced hazard was also observed for breast cancer mortality (HR = 0.73, 95% CI = 0.45 to 1.17) and cardiovascular diseases mortality (HR = 0.76, 95% CI = 0.47 to 1.23), although the 95% confidence intervals included the null. Similar findings were also observed for women without breast cancer. The association with all-cause mortality was more pronounced among breast cancer participants who began chemotherapy before urine collection (n = 118, HR = 0.42, 95% CI = 0.22 to 0.81) than among those who had not (n = 559, HR = 0.98, 95% CI = 0.72 to 1.34; P interaction = .008). CONCLUSIONS: The urinary 2-OHE1 to 16-OHE1 ratio may be inversely associated with long-term all-cause mortality, which may depend on cancer treatment status at the time of urine collection.

Prediagnostic serum concentrations of organochlorine pesticides and non-Hodgkin lymphoma: A nested case-control study in the Norwegian Janus Serum Bank Cohort.

BACKGROUND: Much of the marked increase in incidence of non-Hodgkin lymphoma (NHL) over the past few decades remains unexplained. Organochlorines, including organochlorine pesticides (OCPs), have been implicated as possible contributors to the increase, but the evidence is inconsistent. OBJECTIVES: To investigate the relation between pre-diagnostic levels of OCPs and risk of NHL in a case-control study nested within the population-based Janus Serum Bank Cohort in Norway. METHODS: Prediagnostic concentrations of 11 OCPs or OCP metabolites were measured in baseline blood samples collected between 1972 and 1978 from 190 cases and 190 controls matched on sex, county, age at blood draw, and date of blood draw. We conducted conditional logistic regression to estimate adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) for each quartile of lipid-corrected OCP/metabolite relative to the lowest quartile. RESULTS: We observed non-significantly elevated ORs across quartiles of ß-hexachlorocyclohexane compared to the lowest quartile (OR range: 1.40-1.82) although with no apparent monotonic exposure-response relationship. We also found an inverse association between risk of NHL and o,p'-DDT (OR for Q4 vs. Q1 = 0.44, 95% CI: 0.19, 1.01; p-trend = 0.05). In analyses stratified by age at blood collection and duration of follow-up, several other analytes, primarily chlordane-related compounds, showed inverse associations among younger participants or those with longer follow-up time between blood draw and NHL diagnosis. CONCLUSIONS: We found only limited evidence of positive association between selected OCPs and development of NHL.

Gene expression profiles for low-dose exposure to diethyl phthalate in rodents and humans: a translational study with implications for breast carcinogenesis.

Phthalates are commonly included as ingredients in personal care products such as cosmetics, shampoos and perfumes. Diethyl phthalate (DEP) has been found to be anti-androgenic and linked with adverse reproductive effects on males, but effects on females are poorly understood. We designed an integrative and translational study to experimentally examine the effects of DEP exposure at a human-equivalent dose on the mammary transcriptome in rats and to subsequently examine the DEP gene signature in breast tissues (both pre-malignant and tumor) from a population study. In Sprague-Dawley rats treated orally with DEP from birth to adulthood, we identified a signature panel of 107 genes predominantly down-regulated by DEP exposure. Univariate analysis of this 107 DEP gene signature in pre-malignant breast tissues revealed that six genes (P4HA1, MPZL3, TMC4, PLEKHA6, CA8, AREG) were inversely associated with monoethyl phthalate (MEP; the urinary metabolite of DEP) concentration (p < 0.05) among postmenopausal women; all six genes loaded on to one of seven factors identified by factor analysis. Transcription factor enrichment analysis revealed that genes in this factor were enriched for androgen receptor binding sites. These six genes were also significantly down-regulated in pre-malignant adjacent tissues compared to the corresponding tumor tissues in pair-wise analyses (p < 0.05). Results from our translational study indicate that low level exposure to diethyl phthalate results in measurable genomic changes in breast tissue with implications in breast carcinogenesis.

Diabetes and cardiovascular disease mortality among a population-based cohort of women with and without breast cancer.

PURPOSE: We investigated whether the relationship between diabetes and all-cause and CVD-related mortality differed between women with and without breast cancer among a cohort drawn from the same source population. METHODS: We interviewed 1,363 women newly diagnosed with breast cancer in 1996-1997, and 1,358 age-matched women without breast cancer, to assess history of physician-diagnosed diabetes. All-cause (n = 631) and CVD-specific mortality (n = 234) was determined by the National Death Index through 2009. We estimated multivariable-adjusted hazard ratios (HRs) for the rates of all-cause and CVD-specific mortality and, to account for competing causes of death, and subdistribution HRs (sHRs) for risk of CVD-related death. RESULTS: Among women with and without breast cancer, respectively, diabetes was associated with: all-cause mortality [HR (95% CI) 1.52 (1.13, 2.05) and 2.17 (1.46, 3.22)]; CVD-specific deaths [1.74 (1.06, 2.84) and 2.06 (1.11, 3.84)]; and risk of CVD-related death [sHR 1.36 (0.81, 2.27) and 1.79 (0.94, 3.40)]. Differences in effect estimates between women with and without breast cancer did not reach statistical significance (p-interaction > 0.10). CONCLUSION: We found that the positive association between a history of physician-diagnosed diabetes and risk of all-cause and CVD-related mortality is of similar magnitude among a population-based cohort of women with or without breast cancer.

Early Life Exposure to Air Pollution and Autism Spectrum Disorder: Findings from a Multisite Case-Control Study.

BACKGROUND: Epidemiologic studies have reported associations between prenatal and early postnatal air pollution exposure and autism spectrum disorder (ASD); however, findings differ by pollutant and developmental window. OBJECTIVES: We examined associations between early life exposure to particulate matter ≤2.5 µm in diameter (PM2.5) and ozone in association with ASD across multiple US regions. METHODS: Our study participants included 674 children with confirmed ASD and 855 population controls from the Study to Explore Early Development, a multi-site case-control study of children born from 2003 to 2006 in the United States. We used a satellite-based model to assign air pollutant exposure averages during several critical periods of neurodevelopment: 3 months before pregnancy; each trimester of pregnancy; the entire pregnancy; and the first year of life. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for study site, maternal age, maternal education, maternal race/ethnicity, maternal smoking, and month and year of birth. RESULTS: The air pollution-ASD associations appeared to vary by exposure time period. Ozone exposure during the third trimester was associated with ASD, with an OR of 1.2 (95% CI: 1.1, 1.4) per 6.6 ppb increase in ozone. We additionally observed a positive association with PM2.5 exposure during the first year of life (OR = 1.3 [95% CI: 1.0, 1.6] per 1.6 µg/m increase in PM2.5). CONCLUSIONS: Our study corroborates previous findings of a positive association between early life air pollution exposure and ASD, and identifies a potential critical window of exposure during the late prenatal and early postnatal periods.

Association Between Levels of Sex Hormones and Risk of Esophageal Adenocarcinoma and Barrett's Esophagus.

BACKGROUND & AIMS: Esophageal adenocarcinoma (EAC) occurs most frequently in men. We performed a Mendelian randomization analysis to investigate whether genetic factors that regulate levels of sex hormones are associated with risk of EAC or Barrett's esophagus (BE). METHODS: We conducted a Mendelian randomization analysis using data from patients with EAC (n = 2488) or BE (n = 3247) and control participants (n = 2127), included in international consortia of genome-wide association studies in Australia, Europe, and North America. Genetic risk scores or single-nucleotide variants were used as instrumental variables for 9 specific sex hormones. Logistic regression provided odds ratios (ORs) with 95% CIs. RESULTS: Higher genetically predicted levels of follicle-stimulating hormones were associated with increased risks of EAC and/or BE in men (OR, 1.14 per allele increase; 95% CI, 1.01-1.27) and in women (OR, 1.28; 95% CI, 1.03-1.59). Higher predicted levels of luteinizing hormone were associated with a decreased risk of EAC in men (OR, 0.92 per SD increase; 95% CI, 0.87-0.99) and in women (OR, 0.93; 95% CI, 0.79-1.09), and decreased risks of BE (OR, 0.88; 95% CI, 0.77-0.99) and EAC and/or BE (OR, 0.89; 95% CI, 0.79-1.00) in women. We found no clear associations for other hormones studied, including sex hormone-binding globulin, dehydroepiandrosterone sulfate, testosterone, dihydrotestosterone, estradiol, progesterone, or free androgen index. CONCLUSIONS: In a Mendelian randomization analysis of data from patients with EAC or BE, we found an association between genetically predicted levels of follicle-stimulating and luteinizing hormones and risk of BE and EAC.

Tumor expression of environmental chemical-responsive genes and breast cancer mortality.

Environmental phenols and phthalates are common ingredients in personal care products and some have been implicated in breast cancer progression. We have previously identified genes differentially expressed in response to low-dose exposure to diethyl phthalate (DEP) and methyl paraben (MPB) in a rat model. Herein we explore if these genes are associated with breast cancer mortality in humans. We profiled MPB- and DEP-responsive genes in tumors by NanoString® from a population-based cohort of 606 women with first primary breast cancer among whom 119 breast cancer-specific deaths occurred within 15+ years of follow-up. For each gene, Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Results were validated in two publicly available datasets. The following results were obtained. From 107 DEP- and 77 MPB-responsive genes profiled, 44 and 30 genes, respectively, were significantly associated with breast cancer-specific mortality. Some top DEP-responsive genes are novel for breast cancer mortality, such as ABHD14B (for high-vs-low expression, HR 0.36, 95% CI: 0.2-0.5) and TMC4 (HR 0.37, 95% CI: 0.3-0.5); top hits for MPB (SLC40A1 (HR 0.37, 95% CI: 0.3-0.5) and NTN4 (HR 0.39, 95% CI: 0.3-0.6)) are well-known predictors of breast cancer survival. PLEKHA6 was another novel survival predictor, sensitive to hormonal receptor status (HR 0.5, 95% CI 0.3-0.9 for hormonal receptor-positive and HR 3.2, 95% CI 1.7-6.2 for -negative group). In conclusion, tumor expression of DEP- and MPB-responsive genes is associated with breast cancer mortality, supporting that exposure to these chemicals may influence the progression of breast cancer.

Reproductive characteristics are associated with gene-specific promoter methylation status in breast cancer.

BACKGROUND: Reproductive characteristics are well-established risk factors for breast cancer, but the underlying mechanisms are not fully resolved. We hypothesized that altered DNA methylation, measured in tumor tissue, could act in concert with reproductive factors to impact breast carcinogenesis. METHODS: Among a population-based sample of women newly diagnosed with first primary breast cancer, reproductive history was assessed using a life-course calendar approach in an interviewer-administered questionnaire. Methylation-specific polymerase chain reaction and Methyl Light assays were used to assess gene promotor methylation status (methylated vs. unmethylated) for 13 breast cancer-related genes in archived breast tumor tissue. We used case-case unconditional logistic regression to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for associations with age at menarche and parity (among 855 women), and age at first birth and lactation (among a subset of 736 parous women) in association with methylation status. RESULTS: Age at first birth > 27 years, compared with < 23 years, was associated with lower odds of methylation of CDH1 (OR = 0.44, 95% CI = 0.20-0.99) and TWIST1 (OR = 0.48, 95% CI = 0.28-0.82), and higher odds of methylation of BRCA1 (OR = 1.63, 95% CI = 1.14-2.35). Any vs. no lactation was associated with higher odds of methylation of the PGR gene promoter (OR = 1.59, 95% CI = 1.01-2.49). No associations were noted for parity and methylation in any of the genes assayed. CONCLUSIONS: Our findings indicate that age at first birth, lactation and, perhaps age at menarche, are associated with gene promoter methylation in breast cancer, and should be confirmed in larger studies with robust gene coverage.

Diabetes in relation to Barrett's esophagus and adenocarcinomas of the esophagus: A pooled study from the International Barrett's and Esophageal Adenocarcinoma Consortium.

BACKGROUND: Diabetes is positively associated with various cancers, but its relationship with tumors of the esophagus/esophagogastric junction remains unclear. METHODS: Data were harmonized across 13 studies in the International Barrett's and Esophageal Adenocarcinoma Consortium, comprising 2309 esophageal adenocarcinoma (EA) cases, 1938 esophagogastric junction adenocarcinoma (EGJA) cases, 1728 Barrett's esophagus (BE) cases, and 16,354 controls. Logistic regression was used to estimate study-specific odds ratios (ORs) and 95% CIs for self-reported diabetes in association with EA, EGJA, and BE. Adjusted ORs were then combined using random-effects meta-analysis. RESULTS: Diabetes was associated with a 34% increased risk of EA (OR, 1.34; 95% CI, 1.00-1.80; I2  = 48.8% [where 0% indicates no heterogeneity, and larger values indicate increasing heterogeneity between studies]), 27% for EGJA (OR, 1.27; 95% CI, 1.05-1.55; I2  = 0.0%), and 30% for EA/EGJA combined (OR, 1.30; 95% CI, 1.06-1.58; I2  = 34.9%). Regurgitation symptoms modified the diabetes-EA/EGJA association (P for interaction = .04) with a 63% increased risk among participants with regurgitation (OR, 1.63; 95% CI, 1.19-2.22), but not among those without regurgitation (OR, 1.03; 95% CI, 0.74-1.43). No consistent association was found between diabetes and BE. CONCLUSIONS: Diabetes was associated with increased EA and EGJA risk, which was confined to individuals with regurgitation symptoms. Lack of an association between diabetes and BE suggests that diabetes may influence progression of BE to cancer.

Prediagnosis aspirin use, DNA methylation, and mortality after breast cancer: A population-based study.

BACKGROUND: The authors hypothesized that epigenetic changes may help to clarify the underlying biologic mechanism linking aspirin use to breast cancer prognosis. To the authors' knowledge, this is the first epidemiologic study to examine whether global methylation and/or tumor promoter methylation of breast cancer-related genes interact with aspirin use to impact mortality after breast cancer. METHODS: Prediagnosis aspirin use was assessed through in-person interviews within a population-based cohort of 1508 women diagnosed with a first primary breast cancer in 1996 and 1997. Global methylation in peripheral blood was assessed by long interspersed elements-1 (LINE-1) and the luminometric methylation assay. Promoter methylation of 13 breast cancer-related genes was measured in tumor by methylation-specific polymerase chain reaction and the MethyLight assay. Vital status was determined by the National Death Index through December 31, 2014 (N = 202/476 breast cancer-specific/all-cause deaths identified among 1266 women with any methylation assessment and complete aspirin data). Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% CIs, and the likelihood ratio test was used to evaluate multiplicative interactions. RESULTS: All-cause mortality was elevated among aspirin users who had methylated promotor of BRCA1 (HR, 1.67; 95% CI, 1.26-2.22), but not among those with unmethylated promoter of BRCA1 (HR, 0.99; 95% CI, 0.67-1.45; P for interaction ≤.05). Decreased breast cancer-specific mortality was observed among aspirin users who had unmethylated promotor of BRCA1 and PR and global hypermethylation of LINE-1 (HR, 0.60, 0.78, and 0.63, respectively; P for interaction ≤.05), although the 95% CIs included the null. CONCLUSIONS: The current study suggests that the LINE-1 global methylation and promoter methylation of BRCA1 and PR in tumor may interact with aspirin use to influence mortality after breast cancer.

Self-reported residential pesticide use and survival after breast cancer.

INTRODUCTION: Previous investigations found elevated mortality after breast cancer in association with biomarkers of persistent organochlorine pesticides in non-occupationally exposed women. We hypothesized that lifetime residential pesticide use, which includes persistent and non-persistent pesticides, would also be associated with increased mortality after breast cancer. METHODS: A population-based cohort of 1505 women with invasive or in situ breast cancer was interviewed in 1996-1997, shortly after diagnosis, about pre-diagnostic lifetime residential pesticide use. Participants were followed for mortality through 2014 (595 deaths from any cause and 236 from breast cancer, after 17.6 years of follow-up). Pesticides were examined as 15 individual categories; a group of seven used for lawn and garden purposes; a group of eight used for nuisance-pest purposes; and all combined. Cox regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause and breast cancer-specific mortality. Modification by estrogen receptor (ER) status, body mass index, and long-term residence was examined. RESULTS: Ever use (HR = 0.77, 95%CI = 0.63-0.95) and higher lifetime applications (4th quartile: HR = 0.62, 95%CI = 0.47-0.81, ptrend = 0.3) of the lawn and garden group of pesticides were inversely associated with all-cause mortality, compared to never use. The inverse association for lawn and garden pesticide use was limited to ER positive (vs. negative) tumors (pinteraction = 0.05). Nuisance-pest pesticides, and all groups combined, were not associated with all-cause or breast cancer-specific mortality. CONCLUSIONS: Contrary to our hypothesis, lifetime residential use of lawn and garden pesticides, but not all combined or nuisance-pest pesticides, was inversely associated with all-cause mortality after breast cancer.

Airborne mammary carcinogens and breast cancer risk in the Sister Study.

INTRODUCTION: Potentially carcinogenic hazardous air pollutants (air toxics) have been inconsistently associated with breast cancer. Whether metabolic factors modify these associations is unknown. We studied 29 non-metallic air toxics classified as mammary gland carcinogens in animal studies in relation to breast cancer risk. METHODS: Participants included 49,718 women from the Sister Study. Census tract air toxic concentration estimates from the 2005 National Air Toxics Assessment were linked to enrollment residential addresses. Adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for individual air toxics were estimated using Cox regression. Body mass index (BMI) was considered a potential modifier. Relevant mixtures were identified using classification trees. RESULTS: Over follow-up (average = 8.4 years), 2975 women were newly diagnosed with breast cancer (invasive or ductal carcinoma in situ). Several air toxics, including methylene chloride, polycyclic organic matter, propylene dichloride, and styrene, were associated with increased risk. Of these, methylene chloride was most consistently associated with risk across multiple analyses. It was associated with overall (HRquintile 4vs1 = 1.21 (95%CI = 1.07-1.38)) and estrogen receptor positive (ER+) invasive breast cancer (HRquintile 4vs1 = 1.28 (95%CI = 1.08-1.52)) in individual pollutant models, although no dose-response was observed. Associations were stronger among overweight/obese (vs. non-overweight/obese) women (p < 0.05) for six air toxics. The classification tree identified combinations of age, methylene chloride, BMI, and four other toxics (propylene dichloride, ethylene dibromide, ethylidene dichloride, styrene) related to overall breast cancer. CONCLUSIONS: Some non-metallic air toxics, particularly methylene chloride, were associated with the hazard for overall and ER+ breast cancer. Overweight/obese women may be particularly susceptible to air toxics.

Urinary concentrations of environmental phenols and their associations with breast cancer incidence and mortality following breast cancer.

BACKGROUND: Environmental phenols, compounds used widely in personal care and consumer products, are known endocrine disruptors. Few epidemiologic studies have examined the association of phenol biomarkers with breast cancer incidence and, to our knowledge, none have considered associations with mortality following breast cancer. We examined seven urinary phenol biomarkers in association with breast cancer incidence and subsequent mortality, and examined effect measure modification by body mass index (BMI). METHODS: Participants included 711 women with breast cancer and 598 women without breast cancer who were interviewed for the population-based Long Island Breast Cancer Study Project. Among women with breast cancer, phenol biomarkers were quantified in spot urine samples collected on average within three months of a first diagnosis of primary in situ or invasive breast cancer in 1996-1997. Women with breast cancer were monitored for vital status using the National Death Index. After a median follow-up of 17.6 years, we identified 271 deaths, including 98 deaths from breast cancer. We examined creatinine-corrected phenol concentrations and the sum of parabens (Σparabens) in association with breast cancer incidence using logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs), and with mortality using Cox regression to estimate hazard ratios (HRs) and 95% CIs. We evaluated multiplicative effect measure modification using cross-product terms in nested models. RESULTS: The highest (vs lowest) quintiles of urinary methylparaben, propylparaben, and Σparabens were associated with risk of breast cancer with ORs ranging from 1.31 to 1.50. Methylparaben, propylparaben, and Σparabens were also associated with all-cause mortality HRs ranging from 0.68 to 0.77. Associations for breast cancer incidence were more pronounced among women with BMI < 25.0 kg/m2 than among women with BMI ≥ 25.0 kg/m2; however, associations for mortality were more pronounced among women with BMI ≥ 25 kg/m2 than among women with BMI < 25 kg/m2. CONCLUSIONS: Select parabens may have differential associations with risk of developing breast cancer and mortality following breast cancer.

No Association Between Vitamin D Status and Risk of Barrett's Esophagus or Esophageal Adenocarcinoma: A Mendelian Randomization Study.

BACKGROUND & AIMS: Epidemiology studies of circulating concentrations of 25 hydroxy vitamin D (25(OH)D) and risk of esophageal adenocarcinoma (EAC) have produced conflicting results. We conducted a Mendelian randomization study to determine the associations between circulating concentrations of 25(OH)D and risks of EAC and its precursor, Barrett's esophagus (BE). METHODS: We conducted a Mendelian randomization study using a 2-sample (summary data) approach. Six single-nucleotide polymorphisms (SNPs; rs3755967, rs10741657, rs12785878, rs10745742, rs8018720, and rs17216707) associated with circulating concentrations of 25(OH)D were used as instrumental variables. We collected data from 6167 patients with BE, 4112 patients with EAC, and 17,159 individuals without BE or EAC (controls) participating in the Barrett's and Esophageal Adenocarcinoma Consortium, as well as studies from Bonn, Germany, and Cambridge and Oxford, United Kingdom. Analyses were performed separately for BE and EAC. RESULTS: Overall, we found no evidence for an association between genetically estimated 25(OH)D concentration and risk of BE or EAC. The odds ratio per 20 nmol/L increase in genetically estimated 25(OH)D concentration for BE risk estimated by combining the individual SNP association using inverse variance weighting was 1.21 (95% CI, 0.77-1.92; P = .41). The odds ratio for EAC risk, estimated by combining the individual SNP association using inverse variance weighting, was 0.68 (95% CI, 0.39-1.19; P = .18). CONCLUSIONS: In a Mendelian randomization study, we found that low genetically estimated 25(OH)D concentrations were not associated with risk of BE or EAC.

Reproductive characteristics modify the association between global DNA methylation and breast cancer risk in a population-based sample of women.

DNA methylation has been implicated in breast cancer aetiology, but little is known about whether reproductive history and DNA methylation interact to influence carcinogenesis. This study examined modification of the association between global DNA methylation and breast cancer risk by reproductive characteristics. A population-based case-control study assessed reproductive history in an interviewer-administered questionnaire. Global DNA methylation was measured from white blood cell DNA using luminometric methylation assay (LUMA) and pyrosequencing assay (long interspersed elements-1 (LINE-1). We estimated adjusted odds ratios (ORs) and 95% confidence intervals (CIs) among 1 070 breast cancer cases and 1 110 population-based controls. Effect modification was assessed on additive and multiplicative scales. LUMA methylation was associated with elevated breast cancer risk across all strata (comparing the highest to the lowest quartile), but estimates were higher among women with age at menarche ≤12 years (OR = 2.87, 95%CI = 1.96-4.21) compared to >12 years (OR = 1.66, 95%CI = 1.20-2.29). We observed a 2-fold increase in the LUMA methylation-breast cancer association among women with age at first birth >23 years (OR = 2.62, 95%CI = 1.90-3.62) versus ≤23 years (OR = 1.32, 95% CI = 0.84-2.05). No modification was evident for parity or lactation. Age at menarche and age at first birth may be modifiers of the association between global DNA methylation and breast cancer risk.