Long-Term Exposure to Fine Particulate Matter and Incidence of Esophageal Cancer: A Prospective Study of 0.5 Million Chinese Adults

Background & Aims

Evidence is sparse and inconclusive on the association between long-term fine (≤2.5 μm) particulate matter (PM_2.5) exposure and esophageal cancer. We aimed to assess the association of PM_2.5 with esophageal cancer risk and compared the esophageal cancer risk attributable to PM_2.5 exposure and other established risk factors.

Methods

This study included 510,125 participants without esophageal cancer at baseline from China Kadoorie Biobank. A high-resolution (1 × 1 km) satellite-based model was used to estimate PM_2.5 exposure during the study period. Hazard ratios (HR) and 95% CIs of PM_2.5 with esophageal cancer incidence were estimated using Cox proportional hazard model. Population attributable fractions for PM_2.5 and other established risk factors were estimated.

Results

There was a linear concentration–response relationship between long-term PM_2.5 exposure and esophageal cancer. For each 10-μg/m³ increase in PM_2.5, the HR was 1.16 (95% CI, 1.04–1.30) for esophageal cancer incidence. Compared with the first quarter of PM_2.5 exposure, participants in the highest quarter had a 1.32-fold higher risk for esophageal cancer, with an HR of 1.32 (95% CI, 1.01–1.72). The population attributable risk because of annual average PM_2.5 concentration ≥35 μg/m³ was 23.3% (95% CI, 6.6%–40.0%), higher than the risks attributable to lifestyle risk factors.

Conclusions

This large prospective cohort study of Chinese adults found that long-term exposure to PM_2.5 was associated with an elevated risk of esophageal cancer. With stringent air pollution mitigation measures in China, a large reduction in the esophageal cancer disease burden can be expected.