Abstract 3395: Commute patterns, residential traffic-related air pollution, and lung cancer risk in the prospective UK Biobank cohort study
Authors: Wong Jason Yat-Yang , Jones Rena , Bassig Bryan , Blechter Batel , Hu Wei , Ji Bu-tian , Rothman Nathaniel , Lan Qing 
Published: September 2020

Abstract
Introduction: Commuting to and from work is a daily activity that exposes millions of people to lung carcinogens such as particulate matter, polycyclic aromatic hydrocarbons, and other constituents of traffic-related air pollution (TRAP). Lung cancer is a global health burden and one of the most common malignancies among industrialized western countries such as the United Kingdom (UK). Few epidemiologic studies of TRAP and lung cancer consider the contribution of commute characteristics. To further investigate, we assessed associations between commute patterns, residential nitrogen dioxide (NO2; a surrogate marker for TRAP), and lung cancer risk in the prospective UK Biobank cohort study.
Methods: We analyzed 234,124 employed participants at baseline in 2006-2010. There were 493 incident lung cancer cases diagnosed over an average 7-year follow-up. Subjects were cross-classified into exclusive categories of commute mode (automobile, public transportation, walking, cycling, active mixture, and other mixture) and frequency (regular: &lt;5, often: ≥5 work-bound trips/week). Annual average residential NO2 concentrations in 2005-2007 were estimated from land use regression. Cox regression models were used to estimate associations between commute patterns, quartiles of NO2, and incident lung cancer, adjusted for age, sex, smoking status, race/ethnicity, study center, body mass index, annual income, commute distance, and alcohol intake. Additional analyses were stratified by age, sex, smoking status, NO2 (&gt;, ≤ median2005=28.3 µg/m3) and main job duration (&gt;, ≤10 years). Effect modification was tested using interaction terms.
Results: Most participants only used automobiles to commute (56.5%), while 8.3% only used public transportation (e.g., buses, light-rail, subways), 2.2% only cycled, and 5.0% only walked. Compared to regular automobile use, commuting often by public transportation was strongly associated with increased lung cancer risk (HR=1.68, 95% CI: 1.14-2.47). The association was nominally stronger among high-NO2 residences, men, and ever-smokers, while similar by job duration. There was evidence for effect modification of the association by residential NO2 (p-interaction=0.03) and sex-smoking status (p-interactions=0.03 and 0.09 for former- and current-smoking men, respectively). The other commute categories were not associated with risk. Furthermore, there was a positive exposure-response relationship with NO2 (HRQ2=1.23, 95% CI:0.91-1.65; HRQ3=1.51, 95% CI:1.12-2.03; HRQ4=1.61, 95% CI:1.15-2.27; p-trend=2.1 × 10−3).
Conclusions: Our findings suggest that commuters who often use public transportation have elevated lung cancer risk, possibly driven by time spent in transit microenvironments with high TRAP-levels. Although there are health benefits of public transit use, the competing risk of lung cancer warrants consideration.
Citation Format: Jason Yat-Yang Wong, Rena Jones, Bryan Bassig, Batel Blechter, Wei Hu, Bu-tian Ji, Nathaniel Rothman, Qing Lan. Commute patterns, residential traffic-related air pollution, and lung cancer risk in the prospective UK Biobank cohort study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3395.