A meta-analysis of occupational trichloroethylene exposure and selected cancers

Purpose This review and meta-analysis evaluated occupational studies of TCE exposure and leukemia, non-Hodgkinʹs lymphoma (NHL), and cancers of the lung, kidney, liver, and esophagus. Methods We summarized findings among occupational cohort studies and case-control studies that attempted to specifically identify and characterize TCE exposure. We identified 25 epidemiologic studies that met our inclusion criteria (17 cohort studies, 8 case-control studies). Cohort studies were categorized into “Group 1” and “Group 2” studies by type of exposure information available. Results The meta-analysis relative risk estimates (mRR) for kidney cancer suggested homogeneity of findings across studies in the Group 1 category (p value = 0.97) with similar findings among U.S., European, and Aerospace/Aircraft studies. For liver cancer, mRR estimates varied. Aerospace/aircraft workers and Group 2 studies showed no association, whereas across European studies the mRR was slightly elevated. The findings for NHL indicated significant heterogeneity with lower mRRs among United States and aerospace/aircraft worker studies compared to a higher mRR for the European studies. Findings for esophageal cancer across studies were also heterogeneous. Similar to liver cancer and NHL, a pattern of higher mRRs was noted among European studies compared to other subgroups. Conclusion This meta-analysis of occupational TCE exposure and NHL, leukemia, and cancers of the kidney, liver, esophagus, and lung showed no associations with lung and leukemia and inconsistent associations for kidney, liver, NHL and esophageal cancers across the Group 1 cohort studies considered as more informative. Heterogeneity of findings, limitations in exposure assessment and exposure comparability, and differences in disease classification limit interpretation of the epidemiologic data.