Childhood acute lymphoblastic leukemia and indicators of early immune stimulation: a Childhood Leukemia International Consortium study.
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.
Jérémie
J
Rudant
Tracy
T
Lightfoot
Kevin Y
KY
Urayama
Eleni
E
Petridou
John D
JD
Dockerty
Corrado
C
Magnani
Elizabeth
E
Milne
Logan G
LG
Spector
Lesley J
LJ
Ashton
Nikolaos
N
Dessypris
Alice Y
AY
Kang
Margaret
M
Miller
Roberto
R
Rondelli
Jill
J
Simpson
Eftichia
E
Stiakaki
Laurent
L
Orsi
Eve
E
Roman
Catherine
C
Metayer
Claire
C
Infante-Rivard
Jacqueline
J
Clavel
D000293:Adolescent; D001722:Birth Order; D001942:Breast Feeding / Q000706:statistics & numerical data; D016022:Case-Control Studies; D002648:Child; D002656:Child Day Care Centers / Q000706:statistics & numerical data; D002675:Child, Preschool; D006801:Humans; D007239:Infections / Q000453:epidemiology / Q000276:immunology; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000453:epidemiology / Q000276:immunology*
breastfeeding; childhood leukemia; day care; infections