Abstract A46: Vitamin E intake and the lung cancer risk among female nonsmokers: A report from the Shanghai Women's Health Study

Abstract

Abstract Background: Tocopherols, as the major source of vitamin E in diet in China and US, include four isoforms (α, β, γ, and δ) differentiated by the number and position of methyl groups on the chromanol ring. Tocopherols may inhibit carcinogenesis through inhibition of cell proliferation, induction of apoptosis, inhibition of angiogenesis, and enhancement of immune function. Results of past prospective studies and randomized controlled trials that evaluated the association between tocopherols intake and female lung cancer risk have been inconsistent and did not take into consideration lung cancer histology. Methods: We prospectively evaluated the association between tocopherol isoforms from diet, vitamin E supplement use, and lung cancer risk in 72,829 Chinese female nonsmokers aged 40-70 years and participating in the Shanghai Women's Health Study (SWHS). Tocopherol exposure from dietary and supplements sources were assessed through a validated food-frequency questionnaire at baseline and reassessed during follow-up. Cox proportional hazards models with time-dependent analysis were used to calculate multivariate-adjusted Hazard ratios (HRs) and 95% confidence interval (CIs) for lung cancer. All statistical tests were two sided. Results: Between January 1997 and December 2010, 481 study participants were diagnosed with lung cancer after study enrollment. Total dietary tocopherol was inversely associated with lung cancer risk among women complying with suggested dietary guidelines for adequate intake (AI) of tocopherol (14 mg/day or more: HR: 0.73; 95% CI = 0.54-0.99; compared to the lowest category) with a significant dose-response trend (P trend=0.045). Furthermore, borderline significant inverse associations were observed for combined dietary combined β and γ tocopherol (HR: 0.79; 95% CI = 0.59-1.06), and δ-tocopherols intake (HR: 0.78; 95% CI = 0.59-1.04). Additionally, there was a significant interaction effect between vitamin E or multivitamin supplements use and total dietary tocopherol intake in analysis using AI of tocopherol (P interaction = 0.018). In contrast, vitamin E supplement use was associated with a significant increase in lung cancer risk (HR: 1.39; 95% CI = 1.07-1.82). Analyses of lung cancer histology found that vitamin E supplement use was associated with increased risk of adenocarcinoma (HR: 1.79; 95% CI = 1.23-2.60). Exclusion of 45 cases diagnosed within two years of follow-up did not change the HR estimations appreciably. Conclusion: Total dietary tocopherol may be associated with lower lung cancer risk among female non-smokers, while tocopherol from vitamin supplements use was significantly associated with increased lung adenocarcinoma risk. Our results require confirmation in other prospective studies. Citation Format: Qi-Jun Wu, Yong-Bing Xiang, Gong Yang, Hong-Lan Li, Qing Lan, Yu-Tang Gao, Wei Zheng, Xiao-Ou Shu, Jay Fowke. Vitamin E intake and the lung cancer risk among female nonsmokers: A report from the Shanghai Women's Health Study. [abstract]. In: Proceedings of the Twelfth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2013 Oct 27-30; National Harbor, MD. Philadelphia (PA): AACR; Can Prev Res 2013;6(11 Suppl): Abstract nr A46.