Abstract 3005: Pre-diagnostic methylation-based leukocyte profiles and non-small cell lung cancer risk in heavy smokers
Authors: Grieshober Laurie , Graw Stefan , Barnett Matt J. , Goodman Gary E. , Chen Chu , Koestler Devin C. , Marsit Carmen J. , Doherty Jennifer A. 
Published: April 2023

Abstract
Pre-diagnosis circulating leukocyte profiles, including higher white blood cell (WBC) counts and neutrophil-to-lymphocyte ratios (NLR), have been reported to be associated with non-small cell lung cancer (NSCLC) risk. Higher neutrophil levels were recently reported to drive NSCLC-WBC count associations, implicating the innate immune response in NSCLC risk and etiology. Though not directly measurable in bio-banked blood, leukocyte subtype proportions can be estimated using established deconvolution algorithms applied to genome-wide DNA methylation data. We previously reported that NSCLC risk was elevated in heavy smokers with greater pre-diagnosis methylation-derived NLR (mdNLR). Here, we examine the influence of each pre-diagnosis mdNLR leukocyte subtype (neutrophils, and lymphocytes: B, Natural Killer, CD8+T, and CD4+T cells), separately on NSCLC risk. In our nested case-control study from the Beta Carotene and Retinol Efficacy Trial of heavy smokers (≥20 pack years), 243 NSCLC cases were 1:1 matched to controls on age (±5 years), sex, race and ethnicity, enrollment (±2 years), smoking status (ever/never), asbestos exposure, and follow-up time. Methylation was assayed on the Illumina EPIC array in whole blood collected on average 4.4 years (range 0.1-10.1) before diagnosis in NSCLC cases. We assessed conditional logistic regression models for each mdNLR-related leukocyte subtype, dichotomized at the median in controls, and further adjusted for continuous age and smoking pack years at blood draw. We evaluated NSCLC risk overall, and in subgroup strata: histotype, sex, smoking status, asbestos exposure, stage at diagnosis, age at blood draw, age at diagnosis, and time between blood draw and diagnosis. A greater than median level of neutrophils was suggestively associated with NSCLC risk (OR=1.40, 95% CI: 0.93-2.12); this association was restricted to squamous cell carcinoma (SCC n=103 pairs; 2.00, 1.03-3.86), with no association for adenocarcinoma (n=132 pairs; 0.99, 0.57-1.73). SCC-neutrophil associations were strongest among former smokers (n=26 pairs; 6.81, 1.48-31.3), cases with ≤ 4.4 years between blood draw and diagnosis (n=48 pairs; 3.00, 1.10-8.14), cases aged &gt; 64.8 years at blood draw (n=56 pairs; 2.66, 1.05-6.73), and cases diagnosed at stage III or IV (n=61 pairs; 2.21, 0.92-5.30). Greater than median lymphocyte levels were suggestively associated with reduced NSCLC (0.71, 0.47-1.08) and SCC risk (0.62, 0.32-1.21), but less so for adenocarcinoma (0.85, 0.48-1.50). Though statistically imprecise, SCC-lymphocyte associations were strongest for CD4+T cells (0.56, 0.28-1.12). Our results indicate that greater pre-diagnosis neutrophil levels may be a biomarker for SCC, but not adenocarcinoma, in heavy smokers. Given the descriptive nature of this analysis, small sample size, and multiple testing, additional research is needed to replicate these findings.
Citation Format: Laurie Grieshober, Stefan Graw, Matt J. Barnett, Gary E. Goodman, Chu Chen, Devin C. Koestler, Carmen J. Marsit, Jennifer A. Doherty. Pre-diagnostic methylation-based leukocyte profiles and non-small cell lung cancer risk in heavy smokers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3005.