Roadway Proximity and Lung Cancer Risk in NIH-AARP Diet and Health Study Participants

Abstract

BACKGROUND AND AIM: Studies have demonstrated an increased risk of lung cancer with proximity to roadways; traffic-related pollutants are a suspected cause. Few studies have evaluated risks by histologic subtype, which may provide etiologic insight. METHODS: We generated exposure proxies for 499,237 participants in the six states (California, Florida, Louisiana, New Jersey, North Carolina, and Pennsylvania) and two metropolitan areas (Atlanta, Georgia, and Detroit, Michigan) of the NIH-AARP Diet and Health Study cohort using the residential address at enrollment (1995-1996) and U.S. Census TIGER/Line® files. Metrics reflected distance (m) from the residence to the nearest roadway and type (limited access highways, other major highways, secondary roads, neighborhood/local roads). We used Cox regression to estimate hazard ratios (HR) and 95% confidence intervals (CI) for risk of incident lung cancer overall and by histologic subtype in relation to categorized distance (0-49m, 50-199m, and ≥200m). Models were adjusted for age, sex, race/ethnicity, smoking status and intensity, education, family history of cancer, 2010 U.S. Census rurality, and state/metropolitan area. RESULTS:There were 15,639 lung cancers diagnosed in follow-up through 2011. We observed an increased risk of lung cancer for individuals residing ≤49 or 50-199m of any roadway versus ≥200m, with associations slightly stronger for those in closest proximity (HR[≤49m]=1.44, CI:1.11-1.85; HR[50-199m]=1.35, CI:1.05-1.75). Associations appeared driven by proximity to neighborhood/local roads; participants within ≤49m of any roadway were more often close to a neighborhood/local road 94.4% (n=446,223) than a highway or secondary road (5.6%; n=26,642). By histologic subtype, we observed a positive association for adenocarcinoma (HR[≤49m]=1.76, CI:1.13-2.73; HR[50-199m]=1.64, CI:1.05-2.58) and a non-significant association with squamous cell carcinoma (HR[≤49m]=1.39, CI:0.81-2.41; HR[50-199m]=1.26, CI:0.72-2.22). CONCLUSIONS:From this large U.S. study, overall lung cancer risk increases with proximity to roadways, particularly for adenocarcinoma and possibly squamous cell carcinoma. KEYWORDS: Cancer and cancer precursors, Incidence, Environmental Epidemiology, Air pollution, Traffic-related