Occupational and environmental risk factors for salivary gland cancer: a systematic literature review

Occupational and environmental risk factors for salivary gland cancer (SGC) are largely unrecognised. This systematic review is the first to characterise the relationship between employment in specific industries or occupations and risk of SGC, as well as exposure to key occupational and environmental hazards.Studies published up to September 2023 were collected from three electronic databases and systematically screened. The Health Assessment Workplace Collaborative programme was used to tag studies based on pre-established inclusion and exclusion criteria. Studies eligible for inclusion (n=24) underwent an in-depth review to extract key study characteristics and findings, including effect estimates and 95% CIs. Studies were evaluated for influence of key biases. To identify priority sectors and hazards for intervention, effect direction plots were created to analyse the number and quality of studies reporting elevated rates of SGC across industry, occupation and exposure groups.24 articles were included for analysis. Exposure misclassification and confounding bias were a common concern across studies. Industry and occupation groups with the strongest relationship to SGC included cleaning services, material handling, food services, rubber/plastics production, engineering and construction/painting. Exposures with the strongest relationship to SGC included silica dust, cement dust, chlorinated solvents, formaldehyde and white spirits.Several occupational exposures were associated with an elevated risk of SGC, whereas environmental evidence was more limited. Additional research involving larger cohorts with quantitative exposure data is needed to further establish relationships between occupational and environmental exposures and often-overlooked rare cancers like SGC.PROSPERO registration number: CRD42023468037.