Abstract
BackgroundThe aim of this study was to quantitatively summarize the available evidence on the association of breastfeeding with the risk of childhood cancer.MethodsA literature search of PubMed and Embase databases was performed to identify eligible observational studies published from inception to July 17, 2020. The categorical and dose-response meta-analysis was conducted by pooling relative risk (RR) or odds ratio (OR) estimates with 95% confidence intervals (CIs). Potential sources of heterogeneity were detected by meta-regression and stratification analysis. Sensitivity analysis and publication bias test were also carried out.ResultsForty-five articles involving 475,579 individuals were included in the meta-analysis. Among the thirty-three studies on the association between breastfeeding and risk of childhood leukemia, the pooled risk estimates were 0.77 (95% CI, 0.65–0.91) and 0.77 (95% CI 0.63–0.94) for ever versus non/occasional breastfeeding and longest versus shortest breastfeeding duration group, respectively. There was clear indication for non-linear dose-response relationship between breastfeeding duration and the risk of childhood leukemia (P non-linear < 0.001). The most protective effect (OR, 0.66, 95% CI 0.62–0.70) was observed at a breastfeeding duration of 9.6 months. Four studies examined, the association between breastfeeding and risk of childhood neuroblastoma, and significant inverse associations were consistently observed in both the comparisons of ever breastfeeding versus non/occasional breastfeeding (OR = 0.59, 95% CI 0.44–0.81) and longest versus shortest breastfeeding (OR = 0.61, 95% CI 0.44–0.83). However, no associations of breastfeeding with risk of other cancers were found.ConclusionsOur study supports a protective role of breastfeeding on the risk of childhood leukemia, also suggesting a non-linear dose-response relationship. Further studies are warranted to confirm the association between breastfeeding and risk of childhood neuroblastoma.
Highlights
The aim of this study was to quantitatively summarize the available evidence on the association of breastfeeding with the risk of childhood cancer
The pooled effect estimates suggested that breastfeeding was associated with 9% (95% confidence interval (CI), 2– 16%) lower risk of acute lymphoblastic leukemia (ALL), 24% lower risk of Hodgkin’s disease, and 41% lower risk of neuroblastoma, but no associations of breastfeeding with acute nonlymphoblastic leukemia, non-Hodgkin’s lymphoma, central nervous system cancers, malignant germ cell tumors, juvenile bone tumors, or other solid cancers
5545 articles were retrieved for assessment based on title and abstract, of which 116 articles were included for full text evaluation
Summary
The aim of this study was to quantitatively summarize the available evidence on the association of breastfeeding with the risk of childhood cancer. The relationships of breastfeeding with the risk of childhood cancer are inconsistent across studies and the associations may differ by cancer types. Several studies have shown that breastfeeding had a protective effect on childhood cancer and the protection increased with the duration of the breastfeeding [11, 12]. Some previous studies showed no evidence of protection from breastfeeding for childhood cancer, and the analyses by duration of breastfeeding failed to support the protective hypothesis [13, 14]. Other publications have even reported that prolonged breastfeeding was positively associated with the risk of childhood malignant germ cell tumors [17] and leukemia [18]
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