Serum α-tocopherol and subsequent risk of lung cancer among male smokers

Abstract

Background: Higher blood levels of α-tocopherol, the predominant form of vitamin E, have been associated in some studies with a reduced risk of lung cancer, but other studies have yielded conflicting results. To clarify this association, we examined the relationship between prospectively collected serum α-tocopherol and lung cancer in the Alpha-Tocopherol, Beta- Carotene Cancer Prevention (ATBC) Study cohort. Methods: The ATBC Study was a randomized, clinical trial of 29 133 white male smokers from Finland who were 50-69 years old and who had received α-tocopherol (50 mg), β-carotene (20 mg), both, or neither daily for 5-8 years. Data regarding medical histories, smoking, and dietary factors were obtained at study entry, as was a serum specimen for baseline α-tocopherol determination, α-Tocopherol measurements were available for 29 102 of the men, among whom 1144 incident cases of lung cancer were diagnosed during a median observation period of 7.7 years. The association between α-tocopherol and lung cancer was evaluated with the use of multivariate proportional hazards regression. Results: A 19% reduction in lung cancer incidence was observed in the highest versus lowest quintile of serum α-tocopherol (relative risk = 0.81; 95% confidence interval = 0.67- 0.97). There was a stronger inverse association among younger men (<60 years), among men with less cumulative tobacco exposure (<40 years of smoking), and possibly among men receiving α-tocopherol supplementation. Conclusions: In the ATBC Study cohort, higher serum α-tocopherol status is associated with lower lung cancer risk; this relationship appears stronger among younger persons and among those with less cumulative smoke exposure. These findings suggest that high levels of α-tocopherol, if present during the early critical stages of tumorigenesis, may inhibit lung cancer development.