Abstract 5478: Indoor coal smoke exposure, tobacco use, and lung cancer risk in Xuanwei, China

Abstract

Abstract Introduction: Lung cancer rates in Xuanwei County, Yunnan Province are among the highest in China. We have previously reported that indoor combustion of smoky coal for home heating and cooking was associated with increased risk of lung cancer and that this effect varies markedly by coal type. Further, improved stove ventilation is followed by reduction in lung cancer risk. We explored the joint relationship between tobacco use and coal use in Xuanwei men. Methods: We analyzed data from a population-based case-control study of lung cancer in Xuanwei. Cases were identified from four Xuanwei hospitals and controls were selected from the general population by probability sampling. Controls were matched one-to-one with cases on age. In total, 260 cases and 260 controls were analyzed in this study. Tobacco, coal, and solid fuel exposures were tabulated from questionnaires and reported in cigarette pack-years, duration of smoking, and average tons of coal used annually. Odds ratios and 95% confidence intervals were estimated by conditional logistic regression with the main effects of coal, smoking, and coal-smoking interaction terms. Results: Overall, smoking was positively and significantly, although only modestly, associated with lung cancer risk (OR per pack-year: 1.02; 95% CI: 1.01-1.04). The risk of lung cancer per pack-year of smoking decreased as cumulative lifetime use of smoky coal increased (0-50 tons coal: OR: 1.07; 95% CI: 1.01-1.15; >50-150 tons coal: OR: 1.05; 95% CI: 1.01-1.10; >150 tons coal: OR: 1.00; 95% CI: 0.99-1.03; P-interaction: 0.041). Discussion: Our results suggest that the effect of tobacco on lung cancer risk was weaker in men exposed to higher amounts of coal. Results are consistent with previous cohort study findings in Xuanwei. Constituents of coal combustion, such as polycyclic aromatic hydrocarbons, could plausibly act to diminish the carcinogenicity of tobacco through metabolic competition or other possible mechanisms. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5478. doi:1538-7445.AM2012-5478