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Abstract A102: Longer formula feeding and later age at introduction of solids increase the odds ratio of pediatric acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common form of childhood cancer. The literature suggests multiple points of interaction between infant feeding patterns and leukemogenesis whereby diet may influence normal development of the immune system and levels of insulin-like growth factor 1 (IGF-1) in the serum. Thus the intent of the current study is to examine the association between infant feeding practices and age at introduction of solids, on risk of ALL. Incident cases of infant and childhood ALL (N=142, ages 0 to 14 years) were approached and enrolled in a case-control study at Texas Children's Cancer Center (TCCC). Controls (N=284) were recruited at TCCC and satellite clinics, as well as from participants in formative research for the National Children's Study in Houston, San Antonio and Austin, Texas. Cases and controls were frequency matched on age, sex, race and ethnicity. Differences in proportions of breast and bottle feeding between cases and controls were assessed by chi square test. Differences in the mean durations of feeding practices and age at introduction of solids were assessed by Student's t test. The odds ratios (OR) of ALL were calculated using multiple logistic regression analysis in two models with the infant feeding group (independent variables) characterized as follows and a reference group of exclusively breastfed: in the first model, ever formula fed; in the second model, exclusively fed formula or fed both breast milk and formula. A third addressed the effects of durations of breast and formula feeding and age at the introduction of solid foods on the odds of ALL. Each model was calculated before and after adjustment for race, ethnicity, child's age and maternal smoking during pregnancy. Cases started solid foods significantly later than controls. More mothers of cases than controls smoked during pregnancy. Compared to the controls, cases had longer duration of formula feeding, and upon analysis of the exclusive formula versus mixed breast and formula fed, mixed feeding groups had a longer duration of formula intake. In a preliminary multivariate model, each additional month of formula feeding was associated with a 16% (OR: 1.16, 95% CI 1.08-1.25) increased odds of ALL; and likewise each additional month of delaying the age at introduction of solids was also associated with a 14% (OR1.14, 95% CI: 1.04 -1.26) increased odds of ALL after adjustment for covariates. In this ethnically diverse population, duration of formula feeding and age at introduction of solid foods were directly associated with increased odds of ALL. Further research needs to address the factors influencing duration of formula feeding and delay in introduction of solids. Our results highlight the role of energy balance in early life as critical contributors to risk for pediatric ALL. Citation Format: Jeremy Schraw, Yong Q. Dong, Michael E. Scheurer, Steven Hirschfeld, M Fatih Okcu, Michele R. Forman. Longer formula feeding and later age at introduction of solids increase the odds ratio of pediatric acute lymphoblastic leukemia. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr A102.