Fine Particulate Matter Air Pollution and Mortality Risk Among US Cancer Patients and Survivors

Exposure to fine particulate matter (PM_2.5) air pollution has been linked to increased risk of mortality, especially cardiopulmonary and lung cancer mortality. It is unknown if cancer patients and survivors are especially vulnerable to PM_2.5 air pollution exposure. This study evaluates PM_2.5 exposure and risk for cancer and cardiopulmonary mortality in cohorts of US cancer patients and survivors.

A primary cohort of 5 591 168 of cancer patients and a 5-year survivor cohort of 2 318 068 was constructed using Surveillance, Epidemiology, and End Results Program data from 2000 to 2016, linked with county-level estimates of long-term average concentrations of PM_2.5. Cox proportional hazards models were used to estimate PM_2.5-mortality hazard ratios controlling for age-sex-race combinations and individual and county-level covariables.

Of those who died, 26% died of noncancer causes, mostly from cardiopulmonary disease. Minimal PM_2.5-mortality associations were observed for all-cause mortality (hazard ratio [HR] = 1.01, 95% confidence interval [CI] = 1.00 to 1.03) per 10 µg/m³ increase in PM_2.5. Substantial adverse PM_2.5-mortality associations were observed for cardiovascular (HR = 1.32, 95% CI = 1.26 to 1.39), chronic obstructive pulmonary disease (HR = 1.10, 95% CI = 1.01 to 1.20), influenza and pneumonia (HR = 1.55, 95% CI = 1.33 to 1.80), and cardiopulmonary mortality combined (HR = 1.25, 95% CI = 1.21 to 1.30). PM_2.5-cardiopulmonary mortality hazard ratio was higher for cancer patients who received chemotherapy or radiation treatments.

Air pollution is adversely associated with cardiopulmonary mortality for cancer patients and survivors, especially those who received chemotherapy or radiation treatment. Given ubiquitous and involuntary air pollution exposures and large numbers of cancer patients and survivors, these results are of substantial clinical and public health importance.