Abstract C081: Associations of plasma tocopherol levels with lung cancer risk among low-income Americans: Results from the Southern Community Cohort Study

Abstract Background: Previous studies reported inverse associations of plasma tocopherol levels with lung cancer risk. No study has been conducted among African Americans (AAs) or the low-income population. Objectives: We conducted a nested case-control study to investigate the associations of plasma tocopherol levels with lung cancer risk among predominantly low-income AAs and European Americans (EAs) living in the Southeastern United States. Methods: This study included 209 incident lung cancer cases and 406 matched controls nested within the Southern Community Cohort Study. Using pre-diagnostic plasma samples collected at the baseline survey, levels of α-, β/γ-, δ-, and total tocopherol were measured by High-Performance Liquid Chromatography with photo-diode array detection. Levels for tocopherol biomarkers―α-, β/γ-, δ-, and total tocopherol―were categorized on the tertile distribution of controls. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% CIs of lung cancer risk after adjusting for potential confounders, including enrollment age, smoking status, pack-years, alcohol consumption, education, household income, self-report of ever having been diagnosed with chronic obstructive pulmonary disease, body mass index, and intake of vitamin supplements. Results: Mean levels of tocopherol biomarkers (ng/ml) were significantly higher among EAs than AAs (12,446 vs. 9,166 for α-tocopherol, 3,325 vs. 2,860 for β/γ-tocopherol, 373 vs. 353 for δ-tocopherol, and 16,145 vs. 12,378 for total tocopherol, respectively; all p<0.05). Overall, higher plasma levels of total tocopherol were significantly inversely associated with lung cancer risk (ORT3 vs. T1 = 0.53, 95% CI: 0.30-0.92; p-trend=0.023 among all participants). The inverse assocaiton was only significant among EAs (ORT3 vs. T1 = 0.19, 95% CI: 0.05-0.64), not AAs (ORT3 vs. T1 = 1.32, 95% CI: 0.64-2.69; p-interaction=0.18). We also found a significant association between total tocopherol and lung cancer risk among men (ORT3 vs. T1 = 0.44, 95% CI: 0.22-0.92), current smokers (ORT3 vs. T1 = 0.51, 95% CI: 0.27-0.95), and cases who were diagnosed within two years following sample collection (ORT3 vs. T1 = 0.36, 95% CI: 0.15-0.87). We also evaluated the associations of tocopherols structural isomers with lung cancer risk. α-tocopherol was significantly associated with decreased risk of lung cancer among EAs (ORT3 vs. T1 = 0.16, 95% CI: 0.04-0.64), but a non-significantly elevated risk among AAs (ORT3 vs. T1 = 1.32, 95% CI: 0.64-2.69; p-interaction=0.01). No significant associations were found for β/γ- and δ-tocopherols after adjustment for all potential confounders. Conclusion: Higher total and α-tocopherol were significantly associated with reduced lung cancer risk, particularly among EAs, men, current smokers, and shorter duration of a lung cancer diagnosis. Further studies to investigate the racial differences in the biological mechanisms between tocopherol biomarkers and lung cancer are warranted to confirm our findings. Citation Format: Hyung-Suk Yoon, Chris Shidal, Wei Zheng, Yan Sun, Jie Wu, Adrian A. Franke, William J. Blot, Xiao-Ou Shu, Qiuyin Cai. Associations of plasma tocopherol levels with lung cancer risk among low-income Americans: Results from the Southern Community Cohort Study [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr C081.