Longer period of formula feeding may increase ALL risk

By Helen Albert, Senior medwireNews Reporter

Prolonged formula feeding and older age at introduction of solid foods may increase a child's risk for developing acute lymphoblastic leukemia (ALL), suggests research.

"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," commented lead investigator Jeremy Schraw (University of Texas, Austin, USA) at a press conference at the 11th Annual American Association for Cancer Research International Conference on Frontiers in Cancer Prevention Research in Anaheim, California, USA.

"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," he suggested.

To assess the influence of diet on ALL risk, the researchers enrolled 142 ALL patients, aged 0-14 years, and 284 age-, gender, and ethnicity-matched controls.

The team found that children with ALL had started eating solid foods significantly later than control children. They also had a significantly longer duration of formula feeding than controls.

Following multivariate analysis, Schraw and colleagues calculated that each additional month of formula feeding significantly increased a child's risk for ALL by 16% and each additional month delaying the introduction of solid foods significantly increased ALL risk by 14%.

"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."

An additional factor associated with ALL was maternal smoking, with more cases than controls having mothers who smoked during pregnancy.

ALL is the most common childhood cancer. Previous research indicates that there are many possible interactions between infant feeding practices and leukemogenesis. The results of the current study seem to support suggestions that diet may affect normal immunologic development in children and levels of insulin growth factor 1 in serum.

The researchers say that factors influencing formula feeding duration and delayed introduction of solids into the diet should be investigated further.

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