Prolonged formula feeding may increase the odds for pediatric acute lymphoblastic leukemia (ALL), investigators in a case-control study concluded.
Each additional month of formula feeding was associated with a 16% increase in the relative risk of ALL compared with a control group. Every additional month of delay in the start of solid foods increased the odds by 14%.
The findings might reflect the recognized association between breastfeeding and development of an infant's immune system, Jeremy Schraw reported at the American Association for Cancer Research Frontiers in Cancer Prevention Research meeting in Anaheim, Calif.
"One explanation for this co-risk may be that it's the same effect being picked up twice," Schraw, a graduate student at the University of Texas at Austin, said in a statement. "Children being given solid foods later may be receiving formula longer."
ALL is the most common malignancy in children, and several studies have suggested interaction between feeding practices and its development. Some of the evidence suggests interaction among diet, normal immune-system development, and levels of insulin-like growth factor, said Schraw.
To examine the influence of infant feeding patterns on ALL risk, Schraw and colleagues studied 142 children with the hematologic malignancy and compared them with a matched control group of 284 children. The ALL patients ranged in age from under a year to 14.
The study focused on various aspects of formula feeding, breastfeeding, and introduction of solid foods and their relationship with ALL.
Only two baseline characteristics differed between the patients and the control group. The patients began eating solid foods later (8.6 months versus 7), and more of their mothers smoked during pregnancy. All analyses were adjusted for age, race, sex, ethnicity, and maternal smoking during pregnancy.
Evaluation of feeding patterns showed no differences in the proportion of patients and the control group who were breastfed exclusively, fed formula exclusively, or received breast milk and formula. Schraw and colleagues also found no difference in the duration of breastfeeding and the incidence of ALL.
The investigators did find that the ALL patients had been formula fed significantly longer as compared with the control group (10.5 versus 8.1 months, P<0.05). The difference could be attributed to ALL patients who received both breast milk and formula as infants (10.0 versus 6.2 months, P<0.05).
"Our results highlight the role of energy balance in early life as critical contributors to risk for pediatric ALL," Schraw and colleagues concluded.
The investigators cited a need for additional research to identify factors associated with duration of formula feeding and delay in the introduction of solids.
Schraw and co-investigators and no relevant disclosures.
- Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner
American Association for Cancer Research Frontiers in Cancer Prevention ResearchSource Reference: Schraw J, et al "Longer formula feeding and later age at introduction of solids increase the odds ratio of pediatric acute lymphoblastic leukemia" AACR-FCPR 2012; Abstract A102.