Breastfeeding and Childhood Leukemia Incidence

Abstract

IMPORTANCE Childhood cancer is a leading cause of mortality among children and adolescents in the developed world and the incidence increases by 0.9% each year. Leukemia accounts for about 30% of all childhood cancer but its etiology is still mostly unknown.OBJECTIVE To conduct a meta-analysis of available scientific evidence on the association between breastfeeding and childhood leukemia.DATA SOURCES A thorough search for articles published between January 1960 and December 2014 researching the association between breastfeeding and childhood leukemia was conducted on PubMed, the Cochrane Library, and Scopus (performed in July and December 2014), supplemented by manual searches of reference lists.STUDY SELECTION To be included in the meta-analyses, studies had to be case control; include breastfeeding as a measured exposure and leukemia as a measured outcome; include data on breastfeeding duration in months; and be published in a peer-reviewed journal with full text available in English. DATA EXTRACTION AND SYNTHESISThe search identified 24 relevant studies, 17 of which met all inclusion criteria. No publication bias or significant heterogeneity among these 17 studies were detected. The quality of each study that met the inclusion criteria was assessed using the Newcastle-Ottawa Scale. Multiple meta-analyses were conducted using the random effect model on raw data in the StatsDirect statistical program. MAIN OUTCOMES AND MEASURESNo or short duration of breastfeeding and the incidence of childhood leukemia. RESULTSThe meta-analysis of all 17 studies indicated that compared with no or shorter breastfeeding, any breastfeeding for 6 months or longer was associated with a 20% lower risk for childhood leukemia (odds ratio, 0.80; 95% CI, 0.72-0.90). A separate meta-analysis of 15 studies indicated that ever breastfed compared with never breastfed was associated with a 9% lower risk for childhood leukemia (odds ratio, 0.91; 95% CI, 0.80-1.04), although the definition of never breastfed differed between studies. All meta-analyses of subgroups of the 17 studies showed similar associations. Based on current meta-analyses results, 14% to 20% of all childhood leukemia cases may be prevented by breastfeeding for 6 months or more.CONCLUSIONS AND RELEVANCE Breastfeeding is a highly accessible, low-cost public health measure. This meta-analysis that included studies not featured in previous meta-analyses on the subject indicates that promoting breastfeeding for 6 months or more may help lower childhood leukemia incidence, in addition to its other health benefits for children and mothers.

Protective effect of breastfeeding against childhood leukemia in Zhejiang Province, P. R. China: a retrospective case-control study

“…Several studies reported no association between breastfeeding and ALL [14,15]. A meta-analysis indicated that promoting breastfeeding for 6 months or more might help lower the prevalence of childhood leukemia, in addition to its other health benefits for children and mothers [16]. But these data were inadequate, and there is a lack of research among the 1.4 billon people in the P. R. of China.…”

Maternal residential pesticide use and risk of childhood leukemia in Costa Rica

“…However, our results do not show that breastmilk itself contains pesticide residues and an alternative interpretation is that the period of a child's life when breastmilk is consumed may be a time of particular susceptibility to pesticides and other environmental toxins. Breastmilk is an important nutrition source for infants34 and breastfeeding has been associated with numerous health benefits,35 including a reduced risk of childhood acute leukemia among breastfed infants,36 and should never be discouraged. Practices and policies aimed at minimizing the use of pesticides while breastfeeding and during early childhood are warranted to protect children's health.…”

Human milk: composition and health benefits

“…39,47 Amitay et al (2015) have reported that the risk for developing leukemia was reduced by 19% in infants that were any breastfed compared to infants that had never been breastfed. 48 Consistent evidence indicates that breastfeeding is associated with positive cognitive outcome. Specifically, the intelligence quotient in ever breastfed /longer breastfed infants has been reported to be 3.4 (95% CI 2.3-4.6) points higher than that of never breastfed/shorter breastfed infants.…”