Effect of air pollution on lung cancer survival : a nationwide cohort study

Introduction: Although ambient air pollution has been associated with lung cancer incidence, little is known about the effects on a lung cancer survival. This study aims to investigate the effect of air pollution on the survival of lung cancer patients. Methods: We conducted a retrospective cohort study using nationwide lung cancer cohort. The daily levels of particulate matter with diameter ≤10 ㎍ (PM10), PM with diameter ≤2.5 ㎍ (PM2.5), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO) and ozone (O3) were obtained from the Korean Ministry of Environment. A Cox proportional hazard model was used to estimate the risk that associated between air pollutant exposure and lung cancer survival. Results: We analyzed 69,744 cases of lung cancer from Jan 2002 to Dec 2013. The exposure to PM10, SO2, and CO were significant risk factors for lung cancer survival and this patterns were greater in the early stage compared to advanced stage. Although disease status, sex, age, socioeconomic status and smoking history were significant determinant factors of lung cancer survival, exposure to PM10 (HR 1.053, 95% CI 1.049-1.056), SO2 (HR 1.006, 95% CI 1.005-1.007), and CO (HR 1.009, 95% CI 1.007-1.011) were also significant factors when we adjusted other significant risk factors. Conclusions: Our study found that exposure to PM10, SO2, and CO might be a risk factor for lung cancer survival regardless of disease status and other clinical risk factors. Furthermore, the impact of air pollutants exposure was greater in the early stage.