Occupational exposure to benzene and risk of non-Hodgkin lymphoma in an extended follow-up of two population-based prospective cohorts of Chinese men and women.

The carcinogenicity of benzene was reevaluated by the International Agency for Research on Cancer in 2017, with the Working Group reaffirming positive yet inconclusive associations with non-Hodgkin lymphoma (NHL). To extend our previous observation of a significant exposure-response for cumulative occupational benzene exposure and NHL risk among Chinese women in a population-based cohort in Shanghai, we extended follow-up of this cohort and pooled the data with a similarly designed population-based cohort of men in Shanghai. Cumulative exposure estimates were derived for 134,449 participants in the pooled analysis by combining ordinal job-exposure matrix intensity ratings with quantitative benzene measurements from an inspection database of Shanghai factories. Associations between benzene exposure metrics and NHL (n = 363 cases including multiple myeloma [MM]) were assessed using Cox proportional hazard models. Ever occupational exposure to benzene in the pooled population was associated with NHL risk (HR = 1.5, 95% CI = 1.2-2.0), and exposure-response relationships were observed for increasing duration (ptrend = .003) and cumulative exposure (ptrend = .003). Associations with ever exposure, duration, and cumulative exposure were similar for NHL with and without MM in the case definition, including lifetime cumulative exposures in the highest quartile (HR = 1.6, 95% CI = 1.1-2.4 with MM included; HR = 1.7, 95% CI = 1.1-2.7 with MM excluded). An elevated risk of the chronic lymphocytic leukemia subtype was suggested in the pooled analyses (HR for ever vs. never exposure = 2.3, 95% CI = 0.9-5.6). These observations provide additional support for a plausible association between occupational benzene exposure and risk of NHL.

A proteome-wide analysis unveils a core Epstein-Barr virus antibody signature of classic Hodgkin lymphoma across ethnically diverse populations.

Epstein-Barr virus (EBV) is an oncogenic virus associated with various malignancies, including classical Hodgkin lymphoma (cHL). Despite its known association, the specific role of humoral immune response to EBV remains poorly characterized in cHL. To address this, we conducted a study using a custom protein microarray to measure the antibody responses in cHL patients and matched healthy controls recruited from an East-Asian hospital-based case-control study. We identified 16 IgG antibodies significantly elevated in EBV-positive cHL compared with controls, defining an "East-Asian antibody signature of EBV-positive cHL." We evaluated responses against these 16 antibodies in a distinct European population, leveraging data from our previous European cHL case-control study from the UK, Denmark, and Sweden. A subset of antibodies (14/16, 87.5%) from the "East-Asian antibody signature of EBV-positive cHL" exhibited significant associations with cHL in the European population. Conversely, we assessed the "European antibody signature of EBV-positive cHL" identified in our prior study which consisted of 18 EBV antibodies (2 IgA, 16 IgG), in the East-Asian population. A subset of these antibodies (15/18, 83.3%) maintained significant associations with cHL in the East-Asian population. This cross-comparison of antibody signatures underscores the robust generalizability of EBV antibodies across populations. Five anti-EBV IgG antibodies (LMP-1, TK, BALF2, BDLF3, and BBLF1), found in both population-specific antibody signatures, represent a "core signature of EBV-positive cHL." Our findings suggest that the antibody responses targeting these core EBV proteins reflect a specific EBV gene expression pattern, serving as potential biomarkers for EBV-positive cHL independent of population-specific factors.

Epigenome-wide association study of lung cancer among never smokers in two prospective cohorts in Shanghai, China.

BACKGROUND: The aetiology of lung cancer among individuals who never smoked remains elusive, despite 15% of lung cancer cases in men and 53% in women worldwide being unrelated to smoking. Epigenetic alterations, particularly DNA methylation (DNAm) changes, have emerged as potential drivers. Yet, few prospective epigenome-wide association studies (EWAS), primarily focusing on peripheral blood DNAm with limited representation of never smokers, have been conducted. METHODS: We conducted a nested case-control study of 80 never-smoking incident lung cancer cases and 83 never-smoking controls within the Shanghai Women's Health Study and Shanghai Men's Health Study. DNAm was measured in prediagnostic oral rinse samples using Illumina MethylationEPIC array. Initially, we conducted an EWAS to identify differentially methylated positions (DMPs) associated with lung cancer in the discovery sample of 101 subjects. The top 50 DMPs were further evaluated in a replication sample of 62 subjects, and results were pooled using fixed-effect meta-analysis. RESULTS: Our study identified three DMPs significantly associated with lung cancer at the epigenome-wide significance level of p<8.22×10-8. These DMPs were identified as cg09198866 (MYH9; TXN2), cg01411366 (SLC9A10) and cg12787323. Furthermore, examination of the top 1000 DMPs indicated significant enrichment in epithelial regulatory regions and their involvement in small GTPase-mediated signal transduction pathways. Additionally, GrimAge acceleration was identified as a risk factor for lung cancer (OR=1.19 per year; 95% CI 1.06 to 1.34). CONCLUSIONS: While replication in a larger sample size is necessary, our findings suggest that DNAm patterns in prediagnostic oral rinse samples could provide novel insights into the underlying mechanisms of lung cancer in never smokers.

A nested case-control study of untargeted plasma metabolomics and lung cancer among never-smoking women within the prospective Shanghai Women's Health Study.

The etiology of lung cancer in never-smokers remains elusive, despite 15% of lung cancer cases in men and 53% in women worldwide being unrelated to smoking. Here, we aimed to enhance our understanding of lung cancer pathogenesis among never-smokers using untargeted metabolomics. This nested case-control study included 395 never-smoking women who developed lung cancer and 395 matched never-smoking cancer-free women from the prospective Shanghai Women's Health Study with 15,353 metabolic features quantified in pre-diagnostic plasma using liquid chromatography high-resolution mass spectrometry. Recognizing that metabolites often correlate and seldom act independently in biological processes, we utilized a weighted correlation network analysis to agnostically construct 28 network modules of correlated metabolites. Using conditional logistic regression models, we assessed the associations for both metabolic network modules and individual metabolic features with lung cancer, accounting for multiple testing using a false discovery rate (FDR) < 0.20. We identified a network module of 121 features inversely associated with all lung cancer (p = .001, FDR = 0.028) and lung adenocarcinoma (p = .002, FDR = 0.056), where lyso-glycerophospholipids played a key role driving these associations. Another module of 440 features was inversely associated with lung adenocarcinoma (p = .014, FDR = 0.196). Individual metabolites within these network modules were enriched in biological pathways linked to oxidative stress, and energy metabolism. These pathways have been implicated in previous metabolomics studies involving populations exposed to known lung cancer risk factors such as traffic-related air pollution and polycyclic aromatic hydrocarbons. Our results suggest that untargeted plasma metabolomics could provide novel insights into the etiology and risk factors of lung cancer among never-smokers.

Age at lung cancer diagnosis in females versus males who never smoke by race and ethnicity.

BACKGROUND: We characterized age at diagnosis and estimated sex differences for lung cancer and its histological subtypes among individuals who never smoke. METHODS: We analyzed the distribution of age at lung cancer diagnosis in 33,793 individuals across 8 cohort studies and two national registries from East Asia, the United States (US) and the United Kingdom (UK). Student's t-tests were used to assess the study population differences (Δ years) in age at diagnosis comparing females and males who never smoke across subgroups defined by race/ethnicity, geographic location, and histological subtypes. RESULTS: We found that among Chinese individuals diagnosed with lung cancer who never smoke, females were diagnosed with lung cancer younger than males in the Taiwan Cancer Registry (n = 29,832) (Δ years = -2.2 (95% confidence interval (CI):-2.5, -1.9), in Shanghai (n = 1049) (Δ years = -1.6 (95% CI:-2.9, -0.3), and in Sutter Health and Kaiser Permanente Hawai'i in the US (n = 82) (Δ years = -11.3 (95% CI: -17.7, -4.9). While there was a suggestion of similar patterns in African American and non-Hispanic White individuals. the estimated differences were not consistent across studies and were not statistically significant. CONCLUSIONS: We found evidence of sex differences for age at lung cancer diagnosis among individuals who never smoke.

Associations between Longer Leukocyte Telomere Length and Increased Lung Cancer Risk among Never Smokers in Urban China.

BACKGROUND: The complex relationship between measured leukocyte telomere length (LTL), genetically predicted LTL (gTL), and carcinogenesis is exemplified by lung cancer. We previously reported associations between longer pre-diagnostic LTL, gTL, and increased lung cancer risk among European and East Asian populations. However, we had limited statistical power to examine the associations among never smokers by gender and histology. METHODS: To investigate further, we conducted nested case-control analyses on an expanded sample of never smokers from the prospective Shanghai Women's Health Studies (798 cases and 792 controls) and Shanghai Men's Health Studies (161 cases and 162 controls). We broke the case-control matching and used multivariable unconditional logistic regression models to estimate the ORs and 95% confidence intervals (CI) of incident lung cancer and adenocarcinoma (LUAD), in relation to LTL measured using quantitative PCR and gTL determined using a polygenic score. In addition, we conducted Mendelian randomization (MR) using MR-PRESSO. RESULTS: We found striking dose-response relationships between longer LTL and gTL, and increased lung cancer risk among never-smoking women (P trendLTL = 4×10-6; P trendgTL = 3×10-4). Similarly, among never-smoking men, longer measured LTL was associated with over triple the risk compared with those with the shortest (OR, 3.48; 95% CI, 1.85-6.57). The overall results were similar for LUAD among women and men. MR analyses supported causal associations with LUAD among women (OR1 SD gTL, 1.19; 95% CI, 1.03-1.37; P = 0.03). CONCLUSIONS: Longer pre-diagnostic LTL is associated with increased lung cancer risk among never smokers. IMPACT: Our findings firmly support the role of longer telomeres in lung carcinogenesis.

Household air pollution and epigenetic aging in Xuanwei, China.

BACKGROUND: Household air pollution (HAP) from indoor combustion of solid fuel is a global health burden linked to lung cancer. In Xuanwei, China, lung cancer rate for nonsmoking women is among the highest in the world and largely attributed to high levels of polycyclic aromatic hydrocarbons (PAHs) that are produced from combustion of smoky (bituminous) coal used for cooking and heating. Epigenetic age acceleration (EAA), a DNA methylation-based biomarker of aging, has been shown to be highly correlated with biological processes underlying the susceptibility of age-related diseases. We aim to assess the association between HAP exposure and EAA. METHODS: We analyzed data from 106 never-smoking women from Xuanwei, China. Information on fuel type was collected using a questionnaire, and validated exposure models were used to predict levels of 43 HAP constituents. Exposure clusters were identified using hierarchical clustering. EAA was derived for five epigenetic clocks defined as the residuals resulting from regressing each clock on chronological age. We used generalized estimating equations to test associations between exposure clusters derived from predicted levels of HAP exposure, ambient 5-methylchrysene (5-MC), a PAH previously found to be associated with risk of lung cancer, and EAA, while accounting for repeated-measurements and confounders. RESULTS: We observed an increase in GrimAge EAA for clusters with 31 and 33 PAHs reflecting current (ß = 0.77 y per standard deviation (SD) increase, 95 % CI:0.36,1.19) and childhood (ß = 0.92 y per SD, 95 % CI:0.40,1.45) exposure, respectively. 5-MC (ng/m3-year) was found to be associated with GrimAge EAA for current (ß = 0.15 y, 95 % CI:0.05,0.25) and childhood (ß = 0.30 y, 95 % CI:0.13,0.47) exposure. CONCLUSIONS: Our findings suggest that exposure to PAHs from indoor smoky coal combustion, particularly 5-MC, is associated with GrimAge EAA, a biomarker of mortality.

Exposure to smoky coal combustion emissions and leukocyte Alu retroelement copy number.

Household air pollution (HAP) from indoor combustion of solid fuel is a global health burden that has been linked to multiple diseases including lung cancer. In Xuanwei, China, lung cancer rate for non-smoking women is among the highest in the world and largely attributed to high levels of polycyclic aromatic hydrocarbons (PAHs) that are produced from combustion of smoky (bituminous) coal. Alu retroelements, repetitive mobile DNA sequences that can somatically multiply and promote genomic instability have been associated with risk of lung cancer and diesel engine exhaust exposure. We conducted analyses for 160 non-smoking women in an exposure assessment study in Xuanwei, China with a repeat sample from 49 subjects. Quantitative PCR was used to measure Alu repeat copy number relative to albumin gene copy number (Alu/ALB ratio). Associations between clusters derived from predicted levels of 43 HAP constituents, 5-methylchrysene (5-MC), a PAH previously associated with lung cancer in Xuanwei and was selected a priori for analysis, and Alu repeats were analyzed using generalized estimating equations. A cluster of 31 PAHs reflecting current exposure was associated with increased Alu copy number (ß:0.03 per standard deviation change; 95% confidence interval (CI):0.01,0.04; P-value = 2E-04). One compound within this cluster, 5-MC, was also associated with increased Alu copy number (P-value = 0.02). Our findings suggest that exposure to PAHs due to indoor smoky coal combustion may contribute to genomic instability. Additionally, our study provides further support for 5-MC as a prominent carcinogenic component of smoky coal emissions. Further studies are needed to replicate our findings.

Alterations to biomarkers related to long-term exposure to diesel exhaust at concentrations below occupational exposure limits in the European Union and the USA.

BACKGROUND: We previously found that occupational exposure to diesel engine exhaust (DEE) was associated with alterations to 19 biomarkers that potentially reflect the mechanisms of carcinogenesis. Whether DEE is associated with biological alterations at concentrations under existing or recommended occupational exposure limits (OELs) is unclear. METHODS: In a cross-sectional study of 54 factory workers exposed long-term to DEE and 55 unexposed controls, we reanalysed the 19 previously identified biomarkers. Multivariable linear regression was used to compare biomarker levels between DEE-exposed versus unexposed subjects and to assess elemental carbon (EC) exposure-response relationships, adjusted for age and smoking status. We analysed each biomarker at EC concentrations below the US Mine Safety and Health Administration (MSHA) OEL (<106 µg/m3), below the European Union (EU) OEL (<50 µg/m3) and below the American Conference of Governmental Industrial Hygienists (ACGIH) recommendation (<20 µg/m3). RESULTS: Below the MSHA OEL, 17 biomarkers were altered between DEE-exposed workers and unexposed controls. Below the EU OEL, DEE-exposed workers had elevated lymphocytes (p=9E-03, false discovery rate (FDR)=0.04), CD4+ count (p=0.02, FDR=0.05), CD8+ count (p=5E-03, FDR=0.03) and miR-92a-3p (p=0.02, FDR=0.05), and nasal turbinate gene expression (first principal component: p=1E-06, FDR=2E-05), as well as decreased C-reactive protein (p=0.02, FDR=0.05), macrophage inflammatory protein-1ß (p=0.04, FDR=0.09), miR-423-3p (p=0.04, FDR=0.09) and miR-122-5p (p=2E-03, FDR=0.02). Even at EC concentrations under the ACGIH recommendation, we found some evidence of exposure-response relationships for miR-423-3p (ptrend=0.01, FDR=0.19) and gene expression (ptrend=0.02, FDR=0.19). CONCLUSIONS: DEE exposure under existing or recommended OELs may be associated with biomarkers reflective of cancer-related processes, including inflammatory/immune response.

Methylated polycyclic aromatic hydrocarbons from household coal use across the life course and risk of lung cancer in a large cohort of 42,420 subjects in Xuanwei, China.

BACKGROUND: We previously showed that exposure to 5-methylchrysene (5MC) and other methylated polycyclic aromatic hydrocarbons (PAHs) best explains lung cancer risks in a case-control study among non-smoking women using smoky coal in China. Time-related factors (e.g., age at exposure) and non-linear relations were not explored. OBJECTIVE: We investigated the relation between coal-derived air pollutants and lung cancer mortality using data from a large retrospective cohort. METHODS: Participants were smoky (bituminous) or smokeless (anthracite) coal users from a cohort of 42,420 subjects from four communes in XuanWei. Follow-up was from 1976 to 2011, during which 4,827 deaths from lung-cancer occurred. Exposures were predicted for 43 different pollutants. Exposure clusters were identified using hierarchical clustering. Cox regression was used to estimate exposure-response relations for 5MC, while effect modification by age at exposure was investigated for cluster prototypes. A Bayesian penalized multi-pollutant model was fitted on a nested case-control sample, with more restricted models fitted to investigate non-linear exposure-response relations. RESULTS: We confirmed the strong exposure-response relation for 5MC (Hazard Ratio [95% Confidence Interval] = 2.5 [2.4, 2.6] per standard-deviation (SD)). We identified four pollutant clusters, with all but two PAHs in a single cluster. Exposure to PAHs in the large cluster was associated with a higher lung cancer mortality rate (HR [95%CI] = 2.4 [2.2, 2.6] per SD), while exposure accrued before 18 years of age appeared more important than adulthood exposures. Results from the multi-pollutant model identified anthanthrene (ANT) and benzo(a)chrysene (BaC) as risk factors. 5MC remained strongly associated with lung cancer in models that included ANT and BaC and also benzo(a)pyrene (BaP). CONCLUSION: We confirmed the link between PAH exposures and lung cancer in smoky coal users and found exposures before age 18 to be especially important. We found some evidence for the carcinogen 5MC and non-carcinogens ANT and BaC.

Association between diesel exhaust exposure and mitochondrial DNA methylation.

OBJECTIVES: Diesel exhaust is an established human carcinogen, however the mechanisms by which it leads to cancer development are not fully understood. Mitochondrial dysfunction is an established contributor to carcinogenesis. Recent studies have improved our understanding of the role played by epigenetic modifications in the mitochondrial genome on tumorigenesis. In this study, we aim to evaluate the association between diesel engine exhaust (DEE) exposure with mitochondrial DNA (mtDNA) methylation levels in workers exposed to DEE. METHODS: The study population consisted of 53 male workers employed at a diesel engine manufacturing facility in Northern China who were routinely exposed to diesel exhaust in their occupational setting, as well as 55 unexposed male control workers from other unrelated factories in the same geographic area. Exposure to DEE, elemental carbon, organic carbon, and particulate matter (PM2.5) were assessed. mtDNA methylation for CpG sites (CpGs) from seven mitochondrial genes (D-Loop, MT-RNR1, MT-CO2, MT-CO3, MT-ATP6, MT-ATP8, MT-ND5) was measured in blood samples. Linear regression models were used to estimate the associations between DEE, elemental carbon, organic carbon and PM2.5 exposures with mtDNA methylation levels, adjusting for potential confounders. RESULTS: DEE exposure was associated with decreased MT-ATP6 (difference = -35.6%, P-value = 0.019) and MT-ATP8 methylation (difference = -30%, P-value = 0.029) compared to unexposed controls. Exposures to elemental carbon, organic carbon, and PM2.5 were also significantly and inversely associated with methylation in MT-ATP6 and MT-ATP8 genes (all P-values < 0.05). CONCLUSIONS: Our findings suggest that DEE exposure perturbs mtDNA methylation, which may be of importance for tumorigenesis.

Exposure to diesel engine exhaust and alterations to the Cys34/Lys525 adductome of human serum albumin.

We investigated whether exposure to carcinogenic diesel engine exhaust (DEE) was associated with altered adduct levels in human serum albumin (HSA) residues. Nano-liquid chromatography-high resolution mass spectrometry (nLC-HRMS) was used to measure adducts of Cys34 and Lys525 residues in plasma samples from 54 diesel engine factory workers and 55 unexposed controls. An untargeted adductomics and bioinformatics pipeline was used to find signatures of Cys34/Lys525 adductome modifications. To identify adducts that were altered between DEE-exposed and unexposed participants, we used an ensemble feature selection approach that ranks and combines findings from linear regression and penalized logistic regression, then aggregates the important findings with those determined by random forest. We detected 40 Cys34 and 9 Lys525 adducts. Among these findings, we found evidence that 6 Cys34 adducts were altered between DEE-exposed and unexposed participants (i.e., 841.75, 851.76, 856.10, 860.77, 870.43, and 913.45). These adducts were biologically related to antioxidant activity.

Incidence of myeloid malignancies by subtype in Hong Kong and comparisons with Asian and white men and women in the United States.

Data on incidence rates of myeloid malignancies for subtypes based on the World Health Organization (WHO) classification are lacking in Asian populations. We compared age-adjusted incidence rates for 27 myeloid malignancy WHO-defined subtypes in Hong Kong (HK) (2014-2016) with those for Asian and white individuals living in the United States (U.S.) (2010-2016). Except for overall acute myeloid leukemia (AML) (2.23 cases per 100,000) and myeloproliferative neoplasms (MPNs) (2.10 cases per 100,000), rates of all subtypes were <1 case per 100,000 person-years in HK. Overall rates of AML, myelodysplastic syndrome (MDS), and MDS/MPN were lower in HK compared to white and Asian individuals in the U.S., but the patterns by specific subtype varied. For these three broad groupings of myeloid malignancies, rates in U.S. Asians were intermediate to those in HK and white individuals in the U.S. These results suggest the possibility of a multifactorial etiology for specific myeloid malignancy subtypes that should be evaluated in future epidemiological studies.

Benzene exposure and risk of benzene poisoning in Chinese workers.

OBJECTIVES: Benzene is a known haematoxin and leukemogen that can cause benzene poisoning (BP), that is, a persistent reduction in white cell counts that is strongly associated with increased risk of lymphohaematopoietic malignancies. Data are needed on the exposure-response, particularly at low doses and susceptible populations for clinical and regulatory purposes. METHODS: In a case-cohort study among 110 631 Chinese workers first employed 1949-1987 and followed up during 1972-1999, we evaluated BP risk according to benzene exposure level and investigated risk modification by subject (sex, attained age) and exposure-related factors (latency, exposure windows, age at first benzene exposure, coexposure to toluene) using excess relative risk and excess absolute risk models. RESULTS: There were 538 BP cases and 909 benzene-exposed referents. The exposure metric with best model fit was cumulative benzene exposure during a 5-year risk window, followed by a 9-month lag period before BP diagnosis. Estimated excess absolute risk of BP at age 60 increased from 0.5% for subjects in the lowest benzene exposure category (>0 to 10 ppm-years) to 5.0% for those in the highest category (>100 ppm-years) compared with unexposed subjects. Increased risks were apparent at low cumulative exposure levels and for workers who were first exposed at <30 years of age. CONCLUSIONS: Our data show a clear association between benzene exposure and BP, beginning at low cumulative benzene exposure levels with no threshold, and with higher risks for workers exposed at younger ages. These findings are important because BP has been linked to a strongly increased development of lymphohaematopoietic malignancies.

Characterization of the humoral immune response to the EBV proteome in extranodal NK/T-cell lymphoma.

Extranodal natural killer/T-cell lymphoma (NKTCL) is an aggressive malignancy that has been etiologically linked to Epstein-Barr virus (EBV) infection, with EBV gene transcripts identified in almost all cases. However, the humoral immune response to EBV in NKTCL patients has not been well characterized. We examined the antibody response to EBV in plasma samples from 51 NKTCL cases and 154 controls from Hong Kong and Taiwan who were part of the multi-center, hospital-based AsiaLymph case-control study. The EBV-directed serological response was characterized using a protein microarray that measured IgG and IgA antibodies against 202 protein sequences representing the entire EBV proteome. We analyzed 157 IgG antibodies and 127 IgA antibodies that fulfilled quality control requirements. Associations between EBV serology and NKTCL status were disproportionately observed for IgG rather than IgA antibodies. Nine anti-EBV IgG responses were significantly elevated in NKTCL cases compared with controls and had ORshighest vs. lowest tertile > 6.0 (Bonferroni-corrected P-values < 0.05). Among these nine elevated IgG responses in NKTCL patients, three IgG antibodies (all targeting EBNA3A) are novel and have not been observed for other EBV-associated tumors of B-cell or epithelial origin. IgG antibodies against EBNA1, which have consistently been elevated in other EBV-associated tumors, were not elevated in NKTCL cases. We characterize the antibody response against EBV for patients with NKTCL and identify IgG antibody responses against six distinct EBV proteins. Our findings suggest distinct serologic patterns of this NK/T-cell lymphoma compared with other EBV-associated tumors of B-cell or epithelial origin.

Commute patterns, residential traffic-related air pollution, and lung cancer risk in the prospective UK Biobank cohort study.

INTRODUCTION: Commuting exposes millions of people to carcinogens from traffic-related air pollution (TRAP) but is seldomly considered in epidemiologic studies of lung cancer. In the prospective United Kingdom (UK) Biobank cohort study, we investigated associations between commute patterns, residential nitrogen dioxide concentrations (NO2; a surrogate for TRAP), and lung cancer risk. METHODS: We analyzed 234,124 employed participants at baseline (2006-2010). There were 493 incident lung cancer cases diagnosed over an average 7-year follow-up. Subjects were cross-classified into exclusive categories of commute mode (automobile, public transportation, walking, cycling, active mixture, and other mixture) and frequency (regular: 1-4, often: ≥5 work-bound trips/week). Annual average residential NO2 concentrations in 2005-2007 were estimated with land use regression. Multivariable Cox regression was used to estimate associations between commute patterns, NO2 quartiles, and incident lung cancer. We conducted analyses stratified by NO2 (>, ≤median = 28.3 µg/m3) and potential confounders such as sex and smoking. RESULTS: Compared to regular automobile use, commuting often by public transportation was associated with increased lung cancer risk (hazard ratio (HR) = 1.58, 95% confidence intervals (CI):1.08-2.33). Additionally, we found a positive exposure-response relationship with residential NO2 (HRQ2 = 1.21, 95 %CI: 0.90-1.62; HRQ3 = 1.48, 95 %CI: 1.10-1.99; HRQ4 = 1.58, 95 %CI: 1.13-2.23; p-trend = 3.1 × 10-3). The public transportation association was observed among those with higher NO2 (p-interaction = 0.02). Other commute categories were not associated with risk. CONCLUSIONS: Commuters residing in high-NO2 areas who often use public transportation could have elevated lung cancer risk compared to regular automobile users. These results warrant investigations into which component(s) of public transportation contribute to the observed association with increased lung cancer risk.

Elevated Alu retroelement copy number among workers exposed to diesel engine exhaust.

BACKGROUND: Millions of workers worldwide are exposed to diesel engine exhaust (DEE), a known genotoxic carcinogen. Alu retroelements are repetitive DNA sequences that can multiply and compromise genomic stability. There is some evidence linking altered Alu repeats to cancer and elevated mortality risks. However, whether Alu repeats are influenced by environmental pollutants is unexplored. In an occupational setting with high DEE exposure levels, we investigated associations with Alu repeat copy number. METHODS: A cross-sectional study of 54 male DEE-exposed workers from an engine testing facility and a comparison group of 55 male unexposed controls was conducted in China. Personal air samples were assessed for elemental carbon, a DEE surrogate, using NIOSH Method 5040. Quantitative PCR (qPCR) was used to measure Alu repeat copy number relative to albumin (Alb) single-gene copy number in leucocyte DNA. The unitless Alu/Alb ratio reflects the average quantity of Alu repeats per cell. Linear regression models adjusted for age and smoking status were used to estimate relations between DEE-exposed workers versus unexposed controls, DEE tertiles (6.1-39.0, 39.1-54.5 and 54.6-107.7 µg/m3) and Alu/Alb ratio. RESULTS: DEE-exposed workers had a higher average Alu/Alb ratio than the unexposed controls (p=0.03). Further, we found a positive exposure-response relationship (p=0.02). The Alu/Alb ratio was highest among workers exposed to the top tertile of DEE versus the unexposed controls (1.12±0.08 SD vs 1.06±0.07 SD, p=0.01). CONCLUSION: Our findings suggest that DEE exposure may contribute to genomic instability. Further investigations of environmental pollutants, Alu copy number and carcinogenesis are warranted.

A Prospective Investigation of Circulating Metabolome Identifies Potential Biomarkers for Gastric Cancer Risk.

BACKGROUND: Metabolomics is widely used to identify potential novel biomarkers for cancer risk. No investigation, however, has been conducted to prospectively evaluate the role of perturbation of metabolome in gastric cancer development. METHODS: 250 incident cases diagnosed with primary gastric cancer were selected from the Shanghai Women's Health and the Shanghai Men's Health Study, and each was individually matched to one control by incidence density sampling. An untargeted global profiling platform was used to measure approximately 1,000 metabolites in prediagnostic plasma. Conditional logistic regression was utilized to generate ORs and P values. RESULTS: Eighteen metabolites were associated with gastric cancer risk at P < 0.01. Among them, 11 metabolites were lysophospholipids or lipids of other classes; for example, 1-(1-enyl-palmitoyl)-GPE (P-16:0) (OR = 1.56; P = 1.89 × 10-4). Levels of methylmalonate, a suggested biomarker of vitamin B12 deficiency, was correlated with increased gastric cancer risk (OR = 1.42; P = 0.004). Inverse associations were found for three biomarkers for coffee/tea consumption (3-hydroxypyridine sulfate, quinate and N-(2-furoyl) glycine), although the associations were only significant when comparing cases that were diagnosed within 5 years after the blood collection to matched controls. Most of the identified associations were more profound in women and never smokers than their male or ever smoking counterparts and some with notable significant interactions. CONCLUSIONS: Our study identified multiple potential risk biomarkers for gastric cancer independent of Helicobacter pylori infection and other major risk factors. IMPACT: New risk-assessment tools to identify high-risk population could be developed to improve prevention of gastric cancer.See related commentary by Drew et al., p. 1601.

Sub-multiplicative interaction between polygenic risk score and household coal use in relation to lung adenocarcinoma among never-smoking women in Asia.

We previously identified 10 lung adenocarcinoma susceptibility loci in a genome-wide association study (GWAS) conducted in the Female Lung Cancer Consortium in Asia (FLCCA), the largest genomic study of lung cancer among never-smoking women to date. Furthermore, household coal use for cooking and heating has been linked to lung cancer in Asia, especially in Xuanwei, China. We investigated the potential interaction between genetic susceptibility and coal use in FLCCA. We analyzed GWAS-data from Taiwan, Shanghai, and Shenyang (1472 cases; 1497 controls), as well as a separate study conducted in Xuanwei (152 cases; 522 controls) for additional analyses. We summarized genetic susceptibility using a polygenic risk score (PRS), which was the weighted sum of the risk-alleles from the 10 previously identified loci. We estimated associations between a PRS, coal use (ever/never), and lung adenocarcinoma with multivariable logistic regression models, and evaluated potential gene-environment interactions using likelihood ratio tests. There was a strong association between continuous PRS and lung adenocarcinoma among never coal users (Odds Ratio (OR) = 1.69 (95% Confidence Interval (CI) = 1.53, 1.87), p=1 × 10-26). This effect was attenuated among ever coal users (OR = 1.24 (95% CI: 1.03, 1.50), p = 0.02, p-interaction = 6 × 10-3). We observed similar attenuation among coal users from Xuanwei. Our study provides evidence that genetic susceptibility to lung adenocarcinoma among never-smoking Asian women is weaker among coal users. These results suggest that lung cancer pathogenesis may differ, at least partially, depending on exposure to coal combustion products. Notably, these novel findings are among the few instances of sub-multiplicative gene-environment interactions in the cancer literature.

Variation in oral microbiome is associated with future risk of lung cancer among never-smokers.

OBJECTIVE: To prospectively investigate whether diversity in oral microbiota is associated with risk of lung cancer among never-smokers. DESIGN AND SETTING: A nested case-control study within two prospective cohort studies, the Shanghai Women's Health Study (n=74 941) and the Shanghai Men's Health Study (n=61 480). PARTICIPANTS: Lifetime never-smokers who had no cancer at baseline. Cases were subjects who were diagnosed with incident lung cancer (n=114) and were matched 1:1 with controls on sex, age (≤2 years), date (≤30 days) and time (morning/afternoon) of sample collection, antibiotic use during the week before sample collection (yes/no) and menopausal status (for women). MAIN OUTCOMES AND MEASURES: Metagenomic shotgun sequencing was used to measure the community structure and abundance of the oral microbiome in pre-diagnostic oral rinse samples of each case and control. Multivariable logistic regression models were used to estimate the association of lung cancer risk with alpha diversity metrics and relative abundance of taxa. The Microbiome Regression-Based Kernel Association Test (MiRKAT) evaluated the association between risk and the microbiome beta diversity. RESULTS: Subjects with lower microbiota alpha diversity had an increased risk of lung cancer compared with those with higher microbial alpha diversity (Shannon: ptrend=0.05; Simpson: ptrend=0.04; Observed Species: ptrend=0.64). No case-control differences were apparent for beta diversity (pMiRKAT=0.30). After accounting for multiple comparisons, a greater abundance of Spirochaetia (ORlow 1.00 (reference), ORmedium 0.61 (95% CI 0.32 to 1.18), ORhigh 0.42 (95% CI 0.21 to 0.85)) and Bacteroidetes (ORlow 1.00 (reference), ORmedium 0.66 (95% CI 0.35 to 1.25), ORhigh 0.31 (95% CI 0.15 to 0.64)) was associated with a decreased risk of lung cancer, while a greater abundance of the Bacilli class (ORlow 1.00 (reference), ORmedium 1.49 (95% CI 0.73 to 3.08), ORhigh 2.40 (95% CI 1.18 to 4.87)) and Lactobacillales order (ORlow 1.00 (reference), ORmedium 2.15 (95% CI 1.03 to 4.47), ORhigh 3.26 (95% CI 1.58 to 6.70)) was associated with an increased risk of lung cancer. CONCLUSIONS: Our prospective study of never-smokers suggests that lower alpha diversity was associated with a greater risk of lung cancer and the abundance of certain specific taxa was associated with altered risk, providing further insight into the aetiology of lung cancer in the absence of active tobacco smoking.