Associations between Plasma Tocopherols and Lung Cancer Risk: Results from the Southern Community Cohort Study

Abstract

Background: Despite the various anticancer activities of tocopherols, little is known about tocopherols associated with lung cancer risk among low-income African Americans (AA) and European Americans (EA) who are disproportionately affected by the disease.

Methods: We conducted a nested case-control study that included 209 incident lung cancer cases and 406 matched controls within the Southern Community Cohort Study. Using biospecimens collected at cohort enrollment, plasma levels of α-, β/γ-, δ-, and total-tocopherols were measured by high-performance liquid chromatography with photodiode array detection. Conditional logistic regression was used to estimate ORs and 95% confidence intervals (CI) for lung cancer risk after adjusting for potential confounders. Stratified analyses were also conducted.

Results: Plasma levels of total-tocopherols were inversely associated with lung cancer risk overall [OR (95% CI) for the highest vs. lowest tertile = 0.51 (0.30-0.90)]. The inverse association remained significant among EAs [0.20 (0.06-0.65)], men [0.43 (0.21-0.90)], current smokers [0.49 (0.26-0.93)], and cases diagnosed within 2 years of blood draw [0.36 (0.15-0.86)], though we did not find a significant risk reduction among AAs [0.75 (0.39-1.45)]. Notably, we found significant interactions between α-tocopherol and race after controlling the FDR to correct for multiple comparisons (Pinteraction = 0.02).

Conclusions: Our results indicate that plasma total-tocopherols are inversely associated with lung cancer risk, but the association may differ across specific isomeric forms of tocopherols, race, or other individuals' characteristics. Further large-scale studies are warranted to confirm our findings.

Impact: Recommendations on tocopherols for lung cancer prevention should take isomers, race, and smoking behaviors into consideration.

Figure 1.. Association between Plasma Tocopherols and Lung Cancer Risk.

Abbreviations: Ca/Co, number of Cases vs. Controls; OR, odds ratios; 95% CI, 95% confidence interval; T, tertile; Ref, Reference; SD, standard deviation. Plasma levels of each subtype of tocopherol were grouped based on the tertile distributions among total controls. ORs (95% CIs) were adjusted for age, smoking status, pack-years, alcohol consumption, education, household income, history of COPD, BMI, and intake of dietary supplements. p-values for trend were corrected for multiple comparisons by controlling the false discovery rate (FDR). All FDR-adjusted p-values for interaction were greater than 0.05, with the exception of α-tocopherol and race (p-interaction=0.02).