Abstract 3240: Radon exposure, lung cancer, and respiratory outcomes in a cohort of former and current smokers: An ecologic analysis

Background and Objective: Residential radon-222 decay product exposure is the second leading cause of lung cancer overall and the leading cause among nonsmokers. The objective of our study was to assess the potential contribution of radon exposure to lung cancer risk and risk of other respiratory conditions, including chronic obstructive pulmonary disease (COPD), that predispose subjects to lung cancer risk. Methods: Participants were 50- to 79-year-old current and former smokers recruited through the Pittsburgh Lung Screening Study (PLuSS) between January 2002 and April 2005. For the current analysis, we considered a subset of 3,070 (out of 3,654) PLuSS participants living in a six-county area of southwestern Pennsylvania at the time of enrollment. We obtained estimates of residential (basement) radon exposure from the PA Department of Environmental Protection at the zip code level for each of the six counties. These estimates were mean radon concentrations calculated from measurements made at individual residences between 1990 and 2016. We linked each study participant to the mean radon concentration in their zip code and conducted adjusted logistic regressions to explore associations with tertiles of increasing radon exposure and risk of lung cancer, COPD, and emphysema. Models were adjusted for age, sex, individual-level smoking status (former or current), the number of cigarettes smoked per day, and the number of years participants smoked. Results: Mean radon levels for the six-county area ranged from 2 to 16 pCi/L. Comparing the third to the first tertile of radon exposure, the odds ratio for lung cancer was 1.10 (95% CI: 0.77-1.57) and not statistically significant. However, higher radon levels were positively associated with increased odds of COPD diagnosis determined at baseline (odds ratio: 1.19, 95% CI: 0.98-1.43, p: 0.07). In linear regression models using baseline spirometry measurements (specifically, the FEV1/FVC ratio) as the outcome, increasing mean radon levels were associated with decreased lung function (β: -139, p: 0.003). In the PLuSS cohort, lung cancer risk decreases as FEV1/FVC ratios increase (i.e., as lung function improves), after accounting for smoking history (odds ratio: 0.78, 95% CI: 0.68-0.89, p: 0.0002). Conclusions: As COPD is an important predisposing factor for respiratory health, lung cancer development, and overall survival, this potential association between residential radon level and COPD risk warrants additional follow-up. Future work will include using more granular radon measurements to characterize exposure as well as to capture potential changes in exposure status over time. Citation Format: Shaina L. Stacy, Linda Robertson, Renwei Wang, David O. Wilson, Jian-Min Yuan. Radon exposure, lung cancer, and respiratory outcomes in a cohort of former and current smokers: An ecologic analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3240.