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

Jérémie Rudant, Tracy Lightfoot, Kevin Y. Urayama, Eleni Petridou, John D. Dockerty, Corrado Magnani, Elizabeth Milne, Logan G. Spector, Lesley J. Ashton, Nikolaos Dessypris, Alice Y. Kang, Margaret Miller, Roberto Rondelli, Jill Simpson, Eftichia Stiakaki, Laurent Orsi, Eve Roman, Catherine Metayer, Claire Infante-Rivard, Jacqueline Clavel

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75 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)549-562
Number of pages14
JournalAmerican journal of epidemiology
Issue number8
StatePublished - Dec 19 2015

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© 2015 © The Author 2015. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail:


  • breastfeeding
  • childhood leukemia
  • day care
  • infections


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