Methylation-derived Inflammatory Measures and Lung Cancer Risk and Survival

Abstract

ABSTRACTBackgroundExamining inflammation-related DNA methylation alterations in blood could help elucidate the role of inflammation in lung cancer etiology and aid discovery of factors that are key to lung cancer development and progression. In a nested case-control study, we estimated the neutrophil-to-lymphocyte ratio using a validated index, methylation-derived NLR (mdNLR), and quantified DNA methylation levels at loci previously linked with circulating concentrations of C-reactive protein (CRP). We examined associations between these measures and lung cancer risk, and among the cases, lung cancer survival, using pre-diagnostic blood samples of cases (median of 14 years before diagnosis) and controls in the CLUE I/II cohorts. Our analyses controlled for self-reported smoking and methylation-predicted cumulative smoking in order to better focus our examinations on the DNA methylation marks that are informative of the immune response profile.ResultsUsing conditional logistic regression and further adjusting for BMI, batch effects, and a smoking-based methylation score, we observed a 47% increased risk of non-small cell lung cancer (NSCLC) for one standard deviation increase in mdNLR (n = 150 pairs; OR: 1.47 [1.08, 2.02]) and found the estimated CRP Scores to be inversely associated with risk of NSCLC risk after additionally adjusting for methylation-predicted pack-years (n = 150 pairs; Score 1 OR: 0.57 [0.40, 0.81]; Score 2 OR: 0.62 [0.45, 0.84]; Score 3 OR: 0.65 [0.44, 0.95]). Using Cox proportional-hazards models and adjusting age, sex, smoking status, methylation-predicted pack-years, BMI, batch effect, and stage, we observed a 27% increased risk of dying from lung cancer for one standard deviation increase in mdNLR (n = 145 deaths in 205 cases; HR: 1.27 [1.08, 1.50]). A 50% increased risk of dying from lung cancer for one standard deviation increase in mdNLR was observed for NSCLC cases (n = 103 deaths in 149 cases; HR: 1.50 [1.19, 1.89]).ConclusionsA better understanding of inflammation-associated methylation-based biomarkers in lung cancer development could provide insight into critical pathways that may help identify new markers of early disease and survival.