Breastfeeding, Other Early Life Exposures and Childhood Leukemia and Lymphoma

ABSTRACT

Childhood cancer incidence increases and although rare, it is a leading cause of mortality. Leukemia and lymphoma comprise 40% of all cancers in children but little is known of their etiology. In this study, we examined the associations of breastfeeding and other early life exposures with childhood leukemia and lymphoma. A population-based case–control study carried out in 2011–2013 comprised mothers of 190 incidents (2005–2013) of leukemia/lymphoma cases aged 1–19 yr at diagnosis and 384 population-based controls. Interviews based on a computerized structured questionnaire were conducted with the mothers. Multivariate logistic regression models adjusted for potential confounders assessed the association between breastfeeding patterns and childhood leukemia/lymphoma. Ever breastfeeding category was associated with a 64% decreased risk for childhood leukemia/lymphoma lsqb;odds ratio (OR) = 0.36, 95% confidence interval (CI): 0.22, 0.60lrqb; and similar trends, with a dose–response effect, were observed for any breastfeeding (exclusive and/or partial) category for 6, 12, and 18+ mo. Other infant exposures associated with cancer risk were child iron supplementation (OR = 0.39, 95% CI: 0.26, 0.59), pet ownership (OR = 0.50, 95% CI: 0.33, 0.78), paternal smoking (OR = 1.93, 95% CI: 1.18, 3.15), and having older siblings (OR = 1.18, 95% CI: 1.05, 1.33). Breastfeeding—a controllable and modifiable exposure—is inversely associated with risk for childhood leukemia and lymphoma with a dose–response effect.

Acknowledgments

The authors would like to thank the doctors from Meyer Children's Hospital, Rambam Medical Center; Hadassah Ein Kerem Medical Center; Dana Children's Hospital Sourasky Medical Center; Soroka Medical Center; Safra Children's Hospital; and Sheba Medical Center for their cooperation and help in recruiting subjects for this study. The authors are also most grateful to the mothers and fathers participating in the study. The study was part of the requirements for a PhD degree of ELA, supervised by LKB, at the University of Haifa. The study was funded by the Israel Cancer Association, grant nos. 20110038 and 20122006.