Association between laryngeal cancer and asbestos exposure: A systematic review

IMPORTANCE It has been debated whether a link exists between laryngeal cancer and asbestos exposure. Prior systematic reviews have been conducted on this topic, but no updates have been performed on the most recent literature since 2000. OBJECTIVE To provide an updated systematic review of the association between laryngeal cancer and asbestos exposure. EVIDENCE ACQUISITION A search of electronic databases, including PubMed and the Cochrane Library, was performed for articles published between January 1, 2000, and April 30, 2016. Search terms, including laryngeal cancer and asbestos, were used to identify publications reviewing the risk of laryngeal cancer in association with asbestos exposure. Studies analyzing this association that were published in any language and translated reliably were included. Two independent reviewers assessed articles based on predetermined eligibility criteria. Each study was reviewed for quality using the Oxford Centre for Evidence-Based Medicine 2011 Levels of Evidence and assessed for their findings of support for or against a correlation between asbestos exposure and laryngeal cancer. FINDINGS A total of 160 studies were retrieved from all databases, and 2 additional articles were identified by cross-references. Of the 162 articles screened, 15 articles comprising 438 376 study participants were included in this review. Of these 15 studies, 10 showed no correlation between asbestos exposure and laryngeal cancer. The remaining 5 studies claimed a correlation between asbestos exposure and incidence of laryngeal cancer, although only 1 accounted for smoking or alcohol exposure while 3 others did not, and 1 study included only 2 patients. CONCLUSIONS AND RELEVANCE Although asbestos is considered hazardous and carcinogenic, current evidence is lacking to support a correlation between asbestos exposure and laryngeal cancer. Few studies have been able to definitively conclude a causal association between asbestos exposure and laryngeal cancer, and those that found an association often did not account for the confounding factors of tobacco and alcohol exposure.