Occupational benzene exposure and risk of lung cancer: a systematic review and meta-analysis

Lung cancer is a major global health issue, especially among men. While smoking and occupational or environmental exposures are known risks, the role of benzene remains under investigation. We aimed to conduct a systematic review and meta-analysis to evaluate the association between occupational benzene exposure and lung cancer incidence and mortality. We included cohort and case-control studies mentioned in the 2018 IARC Monograph on benzene and performed a systematic literature review to identify studies published up to 2024 by using PubMed, SCOPUS, and EMBASE databases. We constructed forest plots of relative risk (RR) to visualize and analyze the data. A random-effects model was used to address heterogeneity between studies. Stratified analyses were conducted to explore effect modification. We included 44 independent studies in our meta-analysis. The findings didn't reveal an association between total occupational benzene exposure and lung cancer overall (RR = 1.00, 95% CI 0.93-1.07, p-het ≤ 0.001, 45 risk estimates) or in major industries. Stratified analyses suggested an association in case controls studies (RR = 1.16, 95% CI 1.10-1.22: 7 risk estimates, p-het = 0.001), and in studies with results adjusted for smoking (RR = 1.17, 95% CI 1.11-1.24: 6 risk estimates, p-het = 0.001). There was also an association between high-level benzene exposure and lung cancer (p-trend = 0.03). Publication bias was excluded (p = 0.16). The increased risk after adjustment for smoking and the suggestion of a dose-response, are consistent with the hypothesis of an association between benzene exposure and lung cancer risk.