The effect of PM2.5 exposure on the mortality of patients with hepatocellular carcinoma in Tianjin, China

Several studies have shown the effects of PM2.5 exposure on respiratory and cardiovascular systems. However, there is no cohort study evidence of adverse effects of PM2.5 exposure on survival in patients with hepatocellular carcinoma (HCC) in China. This study is aimed at evaluating this association. This cohort study included 1440 HCC patients treated at the Third Central Clinical College of Tianjin Medical University from September 2013 to December 2018. We collected patient information, including demographic data, medical history, lifestyle characteristics, and disease characteristics. Based on PM2.5 concentrations measured at monitoring stations, the inverse distance weighted (IDW) method was used to assess the individuals' exposure during their survival period. Survival status was analysed by the Kaplan-Meier method. Restricted cubic splines and Cox proportional hazards models were used to estimate the relationship between PM2.5 and mortality, and potential confounders were adjusted for. The mortality rate of HCC patients exposed to PM2.5 >= 58.56 mu g/m(3) was significantly higher than that of HCC patients living in environments with PM2.5 < 58.56 mu g/m(3) (79.0% vs 50.7%, P < 0.001). The restricted cubic spline model showed a linear relationship between the PM2.5 concentration and mortality risk (P overall-association < 0.0001 and P nonlinear-association = 0.3568). Cox regression analysis showed that after adjusting for confounding factors, for every 10-mu g/m(3) increase in atmospheric PM2.5, the risk of death for HCC patients increased by 44% [hazard ratio (HR) = 1.44, 95% confidence interval (CI) 1.34, 1.56; P < 0.001]. Compared with patients exposed to PM2.5 <58.56 mu g/m(3), those exposed to PM2.5 = 58.56 mu g/m(3) had a 1.55-fold increased risk of death. Stratified analysis results showed that the effects of PM2.5 on HCC mortality were more significant in patients aged >= 60 years or patients living in central urban areas. We found that exposure to elevated PM2.5 after HCC diagnosis may affect survival, with a higher concentration corresponding to a greater effect.