“For every month that a child was fed formula, taking into account other feeding practices, we found that the risk for this type of cancer was higher,” said Jeremy Schraw, a graduate student at The University of Texas at Austin, who presented the findings of an epidemiological study at the 11th Annual AACR International Conference on Frontiers in Cancer Prevention Research, held Oct. 16-19, 2012. “If a baby is fed only formula, he or she will not be getting any immune factors from the mother, which could be leading to this greater risk.”
Schraw and colleagues surveyed 284 controls and 142 children from the Texas Children’s Cancer Center and the National Children’s Study in Houston, San Antonio and Austin, Texas, who had been diagnosed with acute lymphoblastic leukemia (ALL).
Compared with controls, children diagnosed with ALL started solid foods significantly later, more of their mothers smoked during pregnancy and they had a longer duration of formula feeding.
Researchers found that the risk for developing ALL increased by 16 percent for every month of formula feeding. In addition, for each month the introduction of solid foods was delayed, the risk increased by 14 percent.
“One explanation for this co-risk may be that it’s the same effect being picked up twice,” said Schraw. “Children being given solid foods later may be receiving formula longer.”
Future research should address the factors influencing prolonged formula feeding and delay in solid food introduction, according to the researchers.
A102 Longer formula feeding and later age at introduction of solids increase the odds ratio of pediatric acute lymphoblastic leukemia. Jeremy Schraw1, Yong Q. Dong1, Michael E. Scheurer2, Steven Hirschfeld3, M Fatih Okcu2, Michele R. Forman1. 1University of Texas at Austin, Austin, TX, 2Baylor College of Medicine, Houston, TX, 3National Institute of Child Health and Human Development, Bethesda, MD.
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.