Novel biomarkers of habitual alcohol intake and associations with risk of pancreatic and liver cancers and liver disease mortality

This work was supported by the Intramural Research Program of the National Cancer Institute at the National Institutes of Health. For EPIC-Oxford, it is: Cancer Research UK C8221/A29017 and C8221/A19170, and Medical Research Council MR/M012190/1. RZ-R was supported by the “Miguel Servet” program (CP15/00100) from the Institute of Health Carlos III (Cofunded by the European Social Fund (ESF) - ESF investing in your future). This work was supported in part by the French National Cancer Institute (L’Institut National du Cancer; INCA; grant numbers 2009-139 and 2014-1-RT-02-CIRC-1; PI: M. Jenab). For pancreatic cancer in EPIC the work was supported by internal IARC funds.Background: Alcohol is an established risk factor for several cancers, but modest alcohol-cancer associations may be missed due to measurement error in self-reported assessments. The identification of biomarkers of habitual alcohol intake may enhance evidence on the role of alcohol in cancer onset. Methods: Untargeted metabolomics was used to identify metabolites correlated with habitual alcohol intake in a discovery dataset from the European Prospective Investigation into Cancer and Nutrition (EPIC; n=454). Significant correlations were replicated in independent datasets of controls from casecontrol studies nested within EPIC (n=281) and the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC; n=438) study. Conditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals for associations of alcohol-associated metabolites and selfreported alcohol intake with risk of pancreatic cancer, hepatocellular carcinoma (HCC), liver cancer, and liver disease mortality in the contributing studies. Results: Two metabolites displayed a dose-response association with alcohol intake: 2-hydroxy-3- methylbutyric acid and an unidentified compound (m/z(+):231.0839). A 1-SD increase in log2- transformed levels of 2-hydroxy-3-methylbutyric acid was associated with risk of HCC (OR=2.14; 1.39-3.31) and pancreatic cancer (OR=1.65; 1.17-2.32) in EPIC and liver cancer (OR=2.00; 1.44-2.77) and liver disease mortality (OR=2.16; 1.63-2.86) in ATBC. Conversely, a 1-SD increase in log2- transformed questionnaire-derived alcohol intake was not associated with HCC or pancreatic cancer in EPIC or liver cancer in ATBC but was associated with liver disease mortality (OR=2.19; 1.60-2.98) in ATBC. Conclusions: 2-Hydroxy-3-methylbutyric acid is a candidate biomarker of habitual alcohol intake that may advance the study of alcohol and cancer risk in population-based studies.Intramural Research Program of the National Cancer Institute at the National Institutes of HealthCancer Research UK C8221/A29017 and C8221/A19170Medical Research Council MR/M012190/1“Miguel Servet” program (CP15/00100) from the Institute of Health Carlos III (Cofunded by the European Social Fund (ESF) - ESF investing in your future)French National Cancer Institute 2009-139 and 2014-1-RT-02-CIRC-1IARC fund

A Metabolomic Study of the Variability of the Chemical Composition of Commonly Consumed Coffee Brews

Coffee drinking has been associated with a lower risk of certain chronic diseases and overall mortality. Its effects on disease risk may vary according to the type of coffee brew consumed and its chemical composition. We characterized variations in the chemical profiles of 76 coffee brew samples representing different brew methods, roast levels, bean species, and caffeine types, either prepared or purchased from outlets in Rockville, Maryland, United States of America. Samples were profiled using liquid chromatography coupled with high-resolution mass spectrometry, and the main sources of chemical variability identified by the principal component partial R-square multivariable regression were found to be brew methods (Rpartial2 = 36%). A principal component analysis (PCA) was run on 18 identified coffee compounds after normalization for total signal intensity. The three first principal components were driven by roasting intensity (41% variance), type of coffee beans (29%), and caffeine (8%). These variations were mainly explained by hydroxycinnamoyl esters and diketopiperazines (roasting), N-caffeoyltryptophan, N-p-coumaroyltryptophan, feruloylquinic acids, and theophylline (coffee bean variety) and theobromine (decaffeination). Instant coffees differed from all coffee brews by high contents of diketopiperazines, suggesting a higher roast of the extracted beans. These variations will be important to consider for understanding the effects of different coffee brews on disease risk

Comparison of Collection Methods for Fecal Samples for Discovery Metabolomics in Epidemiologic Studies

BackgroundThe gut metabolome may be associated with the incidence and progression of numerous diseases. The composition of the gut metabolome can be captured by measuring metabolite levels in the feces. However, there are little data describing the effect of fecal sample collection methods on metabolomic measures.MethodsWe collected fecal samples from 18 volunteers using four methods: no solution, 95% ethanol, fecal occult blood test (FOBT) cards, and fecal immunochemical test (FIT). One set of samples was frozen after collection (day 0), and for 95% ethanol, FOBT, and FIT, a second set was frozen after 96 hours at room temperature. We evaluated (i) technical reproducibility within sample replicates, (ii) stability after 96 hours at room temperature for 95% ethanol, FOBT, and FIT, and (iii) concordance of metabolite measures with the putative "gold standard," day 0 samples without solution.ResultsIntraclass correlation coefficients (ICC) estimating technical reproducibility were high for replicate samples for each collection method. ICCs estimating stability at room temperature were high for 95% ethanol and FOBT (median ICC > 0.87) but not FIT (median ICC = 0.52). Similarly, Spearman correlation coefficients (rs) estimating metabolite concordance with the "gold standard" were higher for 95% ethanol (median rs = 0.82) and FOBT (median rs = 0.70) than for FIT (median rs = 0.40).ConclusionsMetabolomic measurements appear reproducible and stable in fecal samples collected with 95% ethanol or FOBT. Concordance with the "gold standard" is highest with 95% ethanol and acceptable with FOBT.ImpactFuture epidemiologic studies should collect feces using 95% ethanol or FOBT if interested in studying fecal metabolomics. Cancer Epidemiol Biomarkers Prev; 25(11); 1483-90. ©2016 AACR