Association between metal(loid)s in serum and leukemia: a systematic review and meta-analysis

Purpose Heavy metals and metalloids are recognized as environmental threats, which are considered highly toxic and carcinogenic. Epidemiologically, their association with leukemia is under debate. We aim to clarify the association between the heavy metal(loid)s in serum and leukemia via a systematic review and meta-analysis. Methods We searched PubMed, Embase, Google Scholar, and CNKI (China National Knowledge Infrastructure) databases for all related articles. The standardized mean difference and its 95% confidence interval was used to evaluate the association of leukemia with heavy metal(loid)s in serum. The statistical heterogeneity among studies was assessed with the Q-test and I 2 statistics. Results Among 4,119 articles related to metal(loid)s and leukemia, 21 studies met our inclusion criteria, which are all cross-sectional studies. These 21 studies involved 1,316 cases and 1,310 controls, based on which we evaluate the association of heavy metals/metalloids in serum with leukemia. Our results indicated positive differences for serum chromium, nickel, and mercury in leukemia patients, while a negative difference for serum manganese in acute lymphocytic leukemia (ALL). Conclusion Our results suggested an elevated trend of serum chromium, nickel, and mercury concentrations in leukemia patients while descending trend of serum manganese concentration in ALL patients. The result of sensitivity analysis between lead, cadmium, and leukemia and publication bias of association between chromium and leukemia also needed attention. Future research work may focus on the dose-response relationship between any of these elements and the leukemia risks, and further elucidation of how these elements are related to leukemia may shed light on the prevention and treatment of leukemia.