Associations of fine particulate matter pollution components with overall, prostate cancer, and cardiovascular disease mortality in men with prostate cancer: A cohort study

Background Over 3.5 million US men are living with prostate cancer (Pica), many with underlying cardiovascular disease (CVD). Fine particulate matter (PM 2.5 ) contributes to higher CVD mortality through inflammation and other mechanisms, and so may increase non-cancer mortality in men with PCa. Methods We conducted a retrospective cohort study of 886,876 men diagnosed with PCa between 2000 to 2015 and followed through 2018 across eight state cancer registries. Annual average predictions of five residential PM 2.5 component exposures (elemental carbon (EC), organic carbon (OC), nitrate, ammonium (NH 4 + ), sulfate (SO 4 2- )) were obtained from an ensemble-based machine learning model and assigned to geomasked addresses at diagnosis within 50 meters (urban) or 1 kilometer (rural). Adjusted hazard ratios (aHR) for associations of components separately and as a mixture with all-cause, PCa, and CVD mortality were estimated from covariate adjusted Cox models. Results There were 233,898 deaths over 5,836,741 person-years. Per interquartile range (IQR) increase, OC (aHR 1.03 [95% CI: 1.02-1.04]), NH 4 + (aHR 1.02 [1.01-1.03]), and SO 4 2- (aHR 1.11 [1.09-1.13]) were associated with all-cause mortality. CVD mortality was associated with higher EC (aHR: 1.04 [1.02-1.06]), OC (aHR 1.05 [1.03, 1.07]), NH 4 + (aHR 1.09 [1.06-1.12]) and SO 4 2- (aHR 1.19 [1.15-1.24]). There were no associations with nitrates or PCa mortality. Per IQR, PM 2.5 components mixtures were associated with higher all-cause (aHR 1.03 [1.02-1.04]), PCa (aHR 1.02 [0.99, 1.05]), and CVD mortality (aHR 1.08 [1.05, 1.11]). Discussion Certain PM 2.5 components were associated with higher all-cause and CVD mortality in men with PCa. Studies of air pollution in cancer survivors should consider impacts on non-cancer mortality.