Air-polluted environmental heavy metal exposure increase lung cancer incidence and mortality: A population-based longitudinal cohort study

Abstract

Background: An increased risk of lung cancer has been observed due to exposure to certain environmental heavy metals. This study elucidated the role of air-polluted heavy metals in the development of lung cancer.

Methods: A longitudinal cohort study involving the general population was conducted to compare heavy metal content among lung cancer patients. The urine concentrations of heavy metals were measured. Questionnaire surveys were designed to collect exposure-related demographic and lifestyle data of the study subjects.

Results: Participants residing near the petrochemical industrial area with higher air Cd concentration had relatively higher urinary concentration of Cd. After adjusting for sociodemographic and behavioral factors, tobacco smoking and air pollution remained as potential sources of Cd exposure. An increased prevalence of lung cancer was observed in the highly polluted zone. The risk of lung cancer incidence increased 1.25-fold for each 1 μg/g-creatinine increase in urine Cd level. Patients with lung cancer had significantly higher urinary Cd concentrations. Lung cancer patients with higher urinary Cd level had significantly poor survival (urine Cd level ≥ 1.58 vs <1.58 μg/g-creatinine; survival, medium, 192.0 vs 342.5 days, p < 0.001). At the longitudinal follow-up, participants with higher urinary Cd level had a higher risk of lung cancer incidence (urine Cd level ≥ 1.58 vs <1.58 μg/g-creatinine: 3.91% v.s. 0.87%, hazard ratio: 4.65, p < 0.001).

Conclusions: Accumulation of Cd could be a risk of lung cancer occurrence. High exposure to Cd may result in poor prognosis in lung cancer patients.

Keywords: Air pollution; Cadmium; Heavy metals; Lung cancer.