Meta-Analysis of the Relationship Between Occupational/Environmental Exposure to Wood Dust and Laryngeal Cancer

Objective

Wood dust is a human carcinogen. However, studies examining the relationship between wood dust exposure and laryngeal cancer have yielded inconsistent findings. Therefore, we systematically reviewed relevant studies examining the relationship between wood dust exposure and laryngeal cancer development, followed by a meta-analysis.

Methods

Publications in the following databases were searched: PubMed, Medline, Embase, Cochrane Library, and China National Knowledge Infrastructure (CNKI). The Newcastle–Ottawa scale was used to evaluate the study quality. A random-effects model was used for the meta-analysis.

Results

Eighteen case–control studies and one cohort study, involving a total of 4426 patients with laryngeal cancer and 319,129 control participants, were identified. The association between occupational/environmental exposure to wood dust and laryngeal cancer, if any, was unclear (adjusted combined OR: 1.11; 95% CI: 0.94–1.31). However, subgroup analyses according to the number of cases, geographic region, publication year, and follow-up duration revealed correlations between wood dust exposure correlated and laryngeal cancer, as follows: number of cases > 200 (OR: 1.14; 95% CI: 1.01–1.25 [n = 10]); studies conducted in the US (OR: 1.21; 95% CI: 1.07–1.37 [n = 5]); follow-up time > 5 years (OR: 1.19; 95% CI: 1.07–1.32 [n = 10]); and publication after the year 2000 (OR: 1.15; 95% CI: 1.04–1.28 [n = 8]). A high heterogeneity in the results was observed (I² = 42.5%, p = 0.024). The results were stable, and no publication bias existed, according to sensitivity analysis.

Conclusions

This meta-analysis suggests that wood dust exposure is associated with laryngeal cancer. Additional large-scale studies are warranted to clarify the relationship between wood dust exposure and laryngeal cancer.