Effect of high-level PM2.5 on survival in lung cancer: a multicenter cohort study from Hebei Province, China

Globally, air pollution is the fourth leading risk factor for death, while lung cancer (LC) is the leading cause of cancer-related death. The aim of this study was to explore the prognostic factors of LC and the influence of high fine particulate matter (PM2.5) on LC survival. Data on LC patients were collected from 133 hospitals across 11 cities in Hebei Province from 2010 to 2015, and survival status was followed up until 2019. The personal PM2.5 exposure concentration (mu g/m(3)) was matched according to the patient's registered address, calculated from a 5-year average for every patient, and stratified into quartiles. The Kaplan-Meier method was used to estimate overall survival (OS), and Cox's proportional hazard regression model was used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs). The 1-, 3-, and 5-year OS rates of the 6429 patients were 62.9%, 33.2%, and 15.2%, respectively. Advanced age (75 years or older: HR = 2.34, 95% CI: 1.25-4.38), subsite at overlapping (HR = 4.35, 95% CI: 1.70-11.1), poor/undifferentiated differentiation (HR = 1.71, 95% CI: 1.13-2.58), and advanced stages (stage III: HR = 2.53, 95% CI: 1.60-4.00; stage IV: HR = 4.00, 95% CI: 2.63-6.09) were risk factors for survival, while receiving surgical treatment was a protective factor (HR = 0.60, 95% CI: 0.44-0.83). Patients exposed to light pollution had the lowest risk of death with a 26-month median survival time. The risk of death in LC patients was greatest at PM2.5 concentrations of 98.7-108.9 mu g/m(3), especially for patients at advanced stage (HR = 1.43, 95% CI: 1.29-1.60). Our study indicates that the survival of LC is severely affected by relatively high levels of PM2.5 pollution, especially in those with advanced-stage cancer.