Title

Childhood acute lymphoblastic leukemia and indicators of early immune stimulation: A childhood leukemia international consortium study

Document Type

Article

Publisher

Oxford University Press

School

School of Exercise and Health Sciences / Child Health Promotion and Research Centre

Comments

Originally published as: Rudant, J., Lightfoot, T., Urayama, K.Y., Petridou, E., Dockerty, J.D., Magnani, C., ... & Clavel, J. (2015). Childhood acute lymphoblastic leukemia and indicators of early immune stimulation: A childhood leukemia international consortium study in American Journal of Epidemiology, 181(8), 549-562. Available here.

Abstract

The associations between childhood acute lymphoblastic leukemia (ALL) and several proxies of early stimulation of the immune system, that is, day-care center attendance, birth order, maternally reported common infections in infancy, and breastfeeding, were investigated by using data from 11 case-control studies participating in the Childhood Leukemia International Consortium (enrollment period: 1980-2010). The sample included 7,399 ALL cases and 11,181 controls aged 2-14 years. The data were collected by questionnaires administered to the parents. Pooled odds ratios and 95% confidence intervals were estimated by unconditional logistic regression adjusted for age, sex, study, maternal education, and maternal age. Day-care center attendance in the first year of life was associated with a reduced risk of ALL (odds ratio = 0.77, 95% confidence interval: 0.71, 0.84), with a marked inverse trend with earlier age at start (P < 0.0001). An inverse association was also observed with breastfeeding duration of 6 months or more (odds ratio = 0.86, 95% confidence interval: 0.79, 0.94). No significant relationship with a history of common infections in infancy was observed even though the odds ratio was less than 1 for more than 3 infections. The findings of this large pooled analysis reinforce the hypothesis that day-care center attendance in infancy and prolonged breastfeeding are associated with a decreased risk of ALL.

DOI

10.1093/aje/kwu298