A new study published earlier this week says that there may be an association between birth weight and an increased risk of overall leukemia. According to the new evidence, high birth weight is linked to overall leukemia and acute lymphoblastic leukemia (ALL), while the higher incidence of acute myeloid leukemia (AML) appears to be associated with both the high and low extremes of birth weight.

"There is a growing body of evidence indicating that childhood leukemia is initiated in utero," said the two study authors, Dr. Robert W. Caughey of the Harvard School of Public Health and Dr. Karin B. Michels of Brigham and Women's Hospital, Boston.

The investigators based their conclusion on an analysis of 32 studies to determine the relationship between birth weight, childhood leukemia, and both acute lymphoblastic leukemia and acute myeloid leukemia. Included in the analysis were 16,501 cases of all types of leukemia, 10,974 cases of ALL, and 1832 cases of AML.

The results revealed that when compared with normal birth weight, high birth weight increased the incidence of overall leukemia by 35 per cent. The authors wrote in the report that for every 1000 gram increase in birth weight, the chances of developing the disease climbed up by 1.18 per cent.

The results of the study also demonstrated that there seems to be a relationship between acute lymphoblastic leukemia and both high and low extremes of birth weight. In fact, low birth weight is associated with a 49 per cent higher incidence in a child developing AML.

The new study supports the notion that childhood leukemia is likely to be initiated in the womb, Dr. Michels said in statement. The expert added that "birth weight is a marker for events during pregnancy that may have affected the risk for leukemia in the offspring."

The researchers said that future studies are needed on the matter in order to investigate thoroughly which factors in the womb exactly are contributing to an increased risk of leukemia. For instance, the risk of developing the disease may be affected by epigenetic factors, modifications to genes other than changes in the DNA sequence itself. Epigenetic modifications may include the addition of molecules, such as methyl groups, to the DNA backbone and other factors that may indirectly affect the expression of the genome.

The study is published in the June 1, 2009 issue of the International Journal of Cancer.

Tags: Leukemia, Pediatrics

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