Modifiable and Non-Modifiable Factors Affecting the Risk of Childhood Leukemia: An Overview of Meta-Analysis

Background and aim: Numerous meta-analyses of childhood leukemia have been published, but no comprehensive study has examined the factors influencing childhood leukemia. In order to introduce these factors to the medical staff and patients, the purpose of this review article was to scrutinize the modifiable and non-modifiable factors affecting the risk of childhood leukemia. Material and methods: Two independent researchers screened the articles studying the effect of modifiable and non-modifiable factors on the childhood leukaemia on the related databases, including Scopus, EMBASE, Cochrane, Web of Science and Medline, without time and language restrictions from inception up to March 10, 2020; any disagreement in this context was judged by a supervisor.Results: Eight meta-analyses were included in the review article. Breastfeeding compared with non-breastfeeding was associated with 9% reduction in the risk of childhood leukemia (Odds ratio (OR) = 0.91; 95% confidence interval (CI) = 0.80-1.04). The children with the birth weight of ≥4,000 g were at higher risk of acute lymphoblastic leukemia when comparing with those with low birth weight (OR = 1.26, 95%CI = 1.17, 1.37). Combining all studies, there was significantly association between childhood leukemia and residential pesticide exposure (summary odds ratio (SOR) = 1.57; 95% CI= 1.27-1.95). There was an association between influenza during pregnancy and higher risk of acute lymphoid leukemia, ALL (pooled OR (POR) = 3.64; 95% CI = 1.34-9.90) and childhood leukemia (POR = 1.77; 95% CI = 1.01-3.11).