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."

"But the study, which is considered preliminary, only found an association between prolonged bottle feeding and ALL; it did not prove a cause-and-effect relationship."