Research appearing in the journal Public Health Reports, suggests that breastfeeding is linked to lower risks of both acute lymphoblastic leukemia (ALL), the most common of the childhood cancers and acute myeloblastic leukemia (AML). The researchers, from the University of California, Berkeley, said their research was the first to systematically review the epidemiologic evidence of the link between maternal breastfeeding and the risk of childhood leukemia. "We conducted this meta-analysis because the studies that had been conducted previously have been inconclusive and contradictory. Our review of the scientific literature shows that the evidence is definitely pointing towards the benefits of breastfeeding when it comes to the risk for two kinds of childhood leukemia, ALL and AML," said researcher Marilyn Kwan.
While the causes of childhood leukemia are not completely understood, it is believed that the disease begins with a gene fusion change that occurs while the fetus is in the womb. The cause of the genetic change is not certain, said Kwan, but it has been shown to interfere with the normal formation and development of blood cells in animals and is found in 25 percent of children with leukemia. Studies indicate that only 1 in 100 children with the gene fusion at birth go on to develop the disease.
"The gene fusion in and of itself doesn't cause leukemia," said Kwan. "There needs to be a second promoting step, a rare response in the child to early infections that can cause a secondary genetic change. That's where breastfeeding may come into play. It could be preventing that second event from occurring because the mother is passing along her antibodies to the child through her breast milk and strengthening the baby's immune system."
Encouragingly, the analysis indicates that even short-term breastfeeding, for less than six months, was linked to a lower risk of ALL. "Our data suggest that breastfeeding for even a short period of time is protective," said co-researcher Buffler. "That's actually not surprising. We know that much of the protection provided by maternal antibodies comes in the first couple of months of breastfeeding, so even breastfeeding for three months is beneficial."
The researchers said there is now enough evidence on the reduced risk of childhood leukemia to recommend breastfeeding. They also cited the other health benefits breastfeeding imparts to the child. "The overall risk of a child developing leukemia is relatively small, so based upon this analysis, people shouldn't be made to feel guilty if they can't breastfeed," said Vincent Kiley, co-author of the paper. "But if you're on the fence about it, this study provides one more reason to encourage women to breastfeed, even if it is for just a couple of months."
