Ambient air pollution and lung cancer risk among never-smokers in the Women's Health Initiative

Abstract

Background: Ambient air pollution is classified as a human carcinogen by the International Agency for Research on Cancer (IARC). However, epidemiologic studies supporting this classification have focused on lung cancer mortality rather than incidence, and spatial and temporal resolutions of exposure estimates have varied considerably across studies. Methods: We evaluated the association of outdoor air pollution and lung cancer incidence among never-smoking participants of the Women’s Health Initiative (WHI) study, a large, US-based cohort of postmenopausal women (N = 65,419; 265 cases). We used geospatial models to estimate exposures to fine particulate matter (PM2.5) and nitrogen dioxide (NO2) based on residential addresses at baseline and throughout follow-up. We also characterized exposures to traffic-related air pollution by proximity to major roadways. We estimated hazard ratios (HRs) for the risk of lung cancer in association with these exposure metrics using Cox proportional hazards regression models. Results: No compelling associations of PM2.5 and NO2 exposures with lung cancer risk were observed. An increased risk of lung cancer was observed when comparing those individuals with residences <50 versus ≥200 meters from a primary limited access highway (HR = 5.23; 95% confidence interval = 1.94, 14.13). Conclusions: Our results do not exclude lung cancer risk estimates observed in association with PM2.5 and NO2 exposures identified in previous studies. Our results suggest that residential proximity to major roadways may be a proxy for carcinogenic exposures not correlated with PM2.5 or NO2 levels. New studies of air pollution and lung cancer incidence should characterize additional aspects of proximity to major roadways.

Exposure to low-level ambient air pollution and the relationship with lung and bladder cancer in older men, in Perth, Western Australia

“…The association between ambient NO 2 and lung cancer has regularly been observed [ 16 , 19 , 23 – 26 , 29 – 32 , 50 , 51 ], although not in all studies [ 27 , 28 ]. In regions with low NO 2 , significant associations with lung cancer have been found in studies conducted in the Netherlands [ 23 – 25 ], the UK [ 50 ], the USA [ 26 ], and Canada [ 16 , 19 ].…”

“…The association between other pollutants and lung cancer is less clear. Significant associations between nitrogen dioxide (NO 2 ) and lung cancer have been identified in regions in Europe [ 23 – 25 ], and North America [ 16 , 19 , 26 ], but the data are not consistent [ 14 , 27 , 28 ]. No associations were observed for studies conducted in China [ 29 ], Korea [ 30 , 31 ], and Iran [ 32 ].…”

Impact of Environmental Exposures on Lung Cancer in Patients Who Never Smoked

“…One study in never‐smoking women found an increased risk of lung cancer when comparing individuals with residences less than 50 versus greater 200 m from a highway [18]. The authors suggest that proximity to major roadways can lead to carcinogenic exposures, though not via elevated PM 2.5 or NO 2 levels [18]. Similar investigations emphasize particulate matter as an important contributor to lung cancer, especially in patients who never smoked.…”

“…There were no differences between patients who smoked and never smoked for distance to major roadway, daily average PM 2.5 , greenspace within 500 m, and distance to our medical center. One study in never‐smoking women found an increased risk of lung cancer when comparing individuals with residences less than 50 versus greater 200 m from a highway [18]. The authors suggest that proximity to major roadways can lead to carcinogenic exposures, though not via elevated PM 2.5 or NO 2 levels [18].…”

The Use of Imaging Tests for the Diagnosis and Management of Lung Nodules

“…In addition, women in all developing countries, and particularly in East and South Asian countries, are exposed to polycyclic aromatic hydrocarbons, which are associated with lung cancer, as result of using cooking oil and other biomass fuels in poorly ventilated areas. Regarding environmental air pollution, the relationship between particulate matter air pollution exposure and lung cancer has been analyzed in two cohorts: the Nurses' Health Study Cohort (15,16), and the Women' s Health Initiative (17). These studies showed an increased risk of incident lung cancer associated with ambient particulate matter exposures and with residential proximity to major roads among neversmoker women.…”