Lung cancer incidence and ambient air pollution in China: a spatial age–period cohort study 1990–2009

Abstract

BackgroundThe International Agency for Research on Cancer has concluded that exposure to outdoor fine particles (PM2·5) is a risk factor for lung cancer. China is experiencing unprecedentedly high levels of PM2·5 air pollution and has the highest lung cancer burden in the world. However, until now, no study has assessed the association between ambient PM2·5 and lung cancer incidence in China. MethodsData of lung cancer incidence between 1990 and 2009 were obtained from the National Cancer Registration of China. The annual concentrations of PM2·5 at 0·1°×0·1° spatial resolution between 1990 and 2005 were estimated by combining remote sensing, global chemical transport models, and ground monitoring air pollution data. A spatial age–period cohort model was used to examine the relative risks (RR) and 95% CI for incident lung cancer associated with increments in 2-year mean PM2·5 concentrations after adjusting for age, period, birth cohort, sex, community type (rural and urban), smoking rate at the community level, as well as the spatial variation in lung cancer incidence. This study was approved by the University of Queensland's behaviour and social sciences ethical review committee (2013000739). FindingsDuring study period, there were 368 762 cases of lung cancer, including 247 533 men and 312 678 cases living in urban areas. The mean concentration of PM2·5 was 69·4 ug/m3. Incident lung cancer was positively associated with increments in 2-year mean PM2·5, and the risk was more pronounced in women (RR 1·149, 95% CI 1·120–1·178) than in men (RR 1·055, 95% CI 1·038–1·072; psex interaction <0·0001). The association was smaller in rural areas (RR 1·037, 95% CI 0·998–1·078) than in urban areas (RR 1·060, 95%CI 1·044–1·075; pinteraction=0·03) and stronger in elderly people (>75 years of age; 1·111 95% CI 1·077–1·146) than young people (30–65 years of age; RR 1·074 95% CI 1·052–1·096; pinteraction=0.007). InterpretationIn China, lung cancer incidence is associated with PM2·5 air pollution. Effective control measures to reduce levels of air pollution are likely to reduce the incidence of lung cancer in the Chinese population. Further studies are still needed to examine causality of the association between PM2·5 and lung cancer incidence, as this study is an observational epidemiology investigation. This study used community-level incidence and air pollution exposure, but not individual-level information on exposure and outcome. We only had air pollution data for the years 1990 and 2005, and interpolated the data to 1990–2009. These might underestimate the association between air pollution and lung cancer incidence, because random measurement error in exposure will bias the effect estimates towards the null. FundingHope Run Malathon Fund (Cancer Institute & Hospital, Chinese Academy of Medical Sciences, LC2011Y41), and University of Queensland Research Fellowship (YG).