Adults who are overweight, obese, or have large waists are more likely to develop a certain type of leukemia.

Graham Giles, PhD, and colleagues aren't blaming leukemia on body size, and they're not trying to scare big-bodied people.

Instead, the researchers are pointing out a pattern they saw among nearly 41,000 people over eight years. Their report appears in the Journal of the National Cancer Institute.

Obesity Linked to Acute Leukemia

Measuring Up

The study included adults in Victoria, Australia, who were 27-75 years old. Their height and weight was checked at the study's start. Those numbers were used to calculate BMI (body mass index).

The researchers also measured participants' waists and muscle mass.

Cases of leukemia and other blood cancers were tracked for about eight years.

Leukemia is divided into two main categories based on the type of affected blood cell — myeloid and lymphoid. The researchers found only an association between body size and myeloid leukemia.

Risk of Death for Obese May Be Declining

Body Size and Leukemia

Among the findings:

—Overweight and obese people (BMI of 25 or greater) were five times as likely to get myeloid leukemia as those of smaller BMI.

—For people with waist sizes over 37 inches, myeloid leukemia risk rose 35 percent for every four extra inches of waist size.

—Increased height was not linked to a higher myeloid leukemia risk.

—Increased muscle mass was also associated with a higher myeloid leukemia risk.

The researchers say that previous studies have shown a relationship between body size and leukemia risk, but the results have been inconsistent.

Though increased weight and body fat have been associated with other types of cancers as well, it's unclear why increased muscle mass might increase leukemia risk.

More research is needed to identify the true association between increased body size and cancer risk.

What is Obesity?

By Miranda Hitti, reviewed by Michael W. Smith, MD

SOURCES: MacInnis, R. Journal of the National Cancer Institute, Aug. 3, 2005; vol 97: pp 1154-1157. American Cancer Society: "Leukemia Classifications." News release, Journal of the National Cancer Institute.