Prolonged formula feeding, delay in solid foods was associated with increased risk for pediatric acute lymphoblastic leukemia

"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 in Anaheim, Calif. 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.