AHRR methylation in heavy smokers: associations with smoking, lung cancer risk, and lung cancer mortality
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RESEARCH ARTICLE
Open Access
AHRR methylation in heavy smokers: associations with smoking, lung cancer risk, and lung cancer mortality Laurie Grieshober1* , Stefan Graw2,3, Matt J. Barnett4, Mark D. Thornquist4, Gary E. Goodman4, Chu Chen4,5,6, Devin C. Koestler2†, Carmen J. Marsit3† and Jennifer A. Doherty1,4†
Abstract Background: A low level of methylation at cg05575921 in the aryl-hydrocarbon receptor repressor (AHRR) gene is robustly associated with smoking, and some studies have observed associations between cg05575921 methylation and increased lung cancer risk and mortality. To prospectively examine whether decreased methylation at cg05575921 may identify high risk subpopulations for lung cancer screening among heavy smokers, and mortality in cases, we evaluated associations between cg05575921 methylation and lung cancer risk and mortality, by histotype, in heavy smokers. Methods: The β-Carotene and Retinol Efficacy Trial (CARET) included enrollees ages 45–69 with ≥ 20 pack-year smoking histories and/or occupational asbestos exposure. A subset of CARET participants had cg05575921 methylation available from HumanMethylationEPIC assays of blood collected on average 4.3 years prior to lung cancer diagnosis in cases. Cg05575921 methylation β-values were treated continuously for a 10% methylation decrease and as quintiles, where quintile 1 (Q1, referent) represents high methylation and Q5, low methylation. We used conditional logistic regression models to examine lung cancer risk overall and by histotype in a nested casecontrol study including 316 lung cancer cases (diagnosed through 2005) and 316 lung cancer-free controls matched on age (±5 years), sex, race/ethnicity, enrollment year, current/former smoking, asbestos exposure, and follow-up time. Mortality analyses included 372 lung cancer cases diagnosed between 1985 and 2013 with available methylation data. We used Cox proportional hazards models to examine mortality overall and by histotype. Results: Decreased cg05575921 methylation was strongly associated with smoking, even in our population of heavy smokers. We did not observe associations between decreased pre-diagnosis cg05575921 methylation and increased lung cancer risk, overall or by histotype. We observed linear increasing trends for lung cancer-specific mortality across decreasing cg05575921 methylation quintiles for adenocarcinoma and small cell carcinoma (Ptrends = 0.01 and 0.04, respectively). (Continued on next page)
* Correspondence: [email protected] † Devin C. Koestler, Carmen J. Marsit and Jennifer A. Doherty contributed equally to this work. 1 Department of Population Health Sciences, Huntsman Cancer Institute, University of Utah, 2000 Circle of Hope Drive, Room 4746, Salt Lake City, UT 84112, USA Full list of author information is available at the end of the article © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or f
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