A systematic review of epidemiologic studies of styrene and cancer.

Previous epidemiology reviews of exposure to styrene and the risk of cancer considered studies published through 13 November 2013. Since then, additional relevant research has been published. No review has included meta-analyses. The current systematic review considered research published through June 2017; included meta-analyses of the relationship between any exposure to styrene and cancers identified as being of concern, including non-Hodgkin lymphoma (NHL), leukemia and cancers of the esophagus, pancreas, lung and kidney; and evaluated several other forms of cancer. Meta-relative risks for all studies were 1.14 (95% confidence interval (CI), 0.91-1.43) for NHL, 1.00 (95% CI, 0.80-1.26) for multiple myeloma, 0.98 (95% CI, 0.87-1.09) for all leukemia, 1.03 (95% CI, 0.92-1.15) for esophageal cancer, 1.02 (95% CI, 0.93-1.12) for pancreatic cancer, 1.09 (95% CI, 0.95-1.24) for lung cancer and 1.10 (95% CI, 0.99-1.22) for kidney cancer. Individual studies provided little evidence of exposure-response or induction time trends. Limitations of the available research and of the meta-analyses included reliance in most studies on mortality data rather than on incidence data, lack of quantitative estimates of styrene exposure for individual subjects and lack of information on lifestyle factors. Consideration of all pertinent data, including substantial recent research, indicates that the epidemiologic evidence on the potential carcinogenicity of styrene is inconclusive and does not establish that styrene causes any form of cancer in humans.