Occupational exposures and lung cancer risk - an analysis of the CARTaGENE study

Abstract

Objective: To investigate the possible associations between selected occupational agents and lung cancer risk. Methods: A case-cohort design was nested within the CARTaGENE study. Cases included all participants with an incident diagnosis of lung cancer occurring during the follow-up from 2009 to 2015 (N=178). For comparison, a sub-cohort of 1033 individuals was established based on a stratified sample of the cohort at baseline. Information on participants’ longest-held job was collected at baseline and coded by an occupational hygienist according to the International Standard Classification of Occupations 1968 (ISCO-68). The job codes were then linked to the Canadian Job Exposure Matrix (CANJEM) to determine the probability of exposure to a list of 258 agents. This analysis was restricted to the 28 most prevalent agents with at least 5 exposed cases. Separate multivariable logistic regression models with robust variance estimators were used to estimate odd ratios (OR) and 95% confidence intervals (95% CI) for the associations between each agent and lung cancer risk while controlling for established lung cancer risk factors, notably smoking. Results: Increased lung cancer risk was found among those exposed to ashes (OR=3.8; 95% CI: 1.5-9.5), hydrogen chloride (OR=4.4; 95% CI: 1.2-16.0), formaldehyde (OR=2.3; 95% CI: 1.3-4.2), cooking fumes (OR=2.4; 95% CI: 1.1-5.3), paints and varnishes used on surfaces other than metal and wood (OR=3.2; 95% CI: 1.0-9.8), alkanes (OR=2.6; 95% CI: 1.2-5.5), aliphatic aldehydes (OR= 2.9; 95% CI: 1.3-4.3), and cleaning agents (OR=1.6; 95% CI: 1.0-2.5). A reduced lung cancer risk was observed among participants exposed to gasoline engine emissions (OR=0.5; 95% CI: 0.2-1.0) and polycyclic aromatic hydrocarbons (PAHs) from petroleum (OR=0.3; 95% CI: 0.1-0.9). Conclusion: Our preliminary findings provide support for the role of several occupational agents, for which we have limited knowledge, in contributing to lung cancer risk.