Increased Girth Raises Risk of Leukemia

NEW YORK (Reuters Health) - Greater body size significantly increases the risk of a type of blood cancer, myeloid leukemia, investigators from Australia report.

"This study adds yet another cancer to the list where we have evidence of increased risk associated with obesity," Dr. Graham G. Giles from the Cancer Council Victoria in Melbourne said. "Controlling the epidemic of obesity in western countries might have a beneficial effect on the population incidence of myeloid leukemia."

Giles and colleagues studied data from a cohort of 40,909 adults who were followed for an average of 8.4 years. The incidence of myeloid leukemia was roughly five times higher among overweight and obese individuals than among individuals with normal or low weight, the researchers report in the Journal of the National Cancer Institute.

Specifically, the risk of myeloid leukemia increased 83 percent for every 10-kilogram increase in fat-free mass, and 35 percent per 10-centimeter increase in waist circumference.

There were no significant relationships between body size or composition and other types of leukemia or lymphoma.

"This study," Giles said, "provides further evidence that maintaining a healthy weight reduces the risk of several types of cancer, including myeloid leukemia."

Giles' team offers several possible explanations for the link between increasing body girth and myeloid leukemia. For example, obesity may alter immune function.

"Nutritional alterations, such as fasting and acute nutritional deprivation, occur frequently in obese persons and can both increase and decrease immunocompetence," they write.

Moreover, central adiposity -- belly fat -- has been shown to increase the risk of several common cancers; this may be related to chronic high levels of insulin and related hormones, which stimulates cell growth and inhibits cell death.

SOURCE: Journal of the National Cancer Institute, August 3, 2005.