Obesity
Compounds Leukemia Risk
It is no surprise that
excess weight increases one's chances of developing cancer. A
new study suggests overweight women 55 and older may be doubling
their risk of developing acute myelogenous leukemia (AML). Further,
older women with a body mass index of 30 or more (obese) have
a 140 percent higher risk of developing the disease.
Claiming the lives
of about one-third of the 33,000 leukemia cases in the United
States a year, AML is one of the deadliest kinds of leukemia.
This is due in part to its aggressive and rapidly developing nature.
Researchers determined
it was important to assess the risk factors associated with developing
AML, as the five-year survival rate is as low as 3 percent.
Thus far, the risk
factors include:
Old age
Excessive weight
Hormones or genetics
Although excess weight is considered a risk factor, it has not
been discovered whether or not losing or normalizing weight can
reduce the risk of AML; however, it remains a possibility.
EurekAlert November
5, 2004
Obesity linked to
another cancer - leukemia in older women
University of Minnesota cancer researcher says shedding excess
pounds may be key in preventing often fatal disease
A study from the University of Minnesota Cancer Center indicates
that overweight and obesity could more than double an older woman's
risk of acute myelogenous leukemia (AML), an often fatal cancer
of the bone marrow and blood.
The results of the
study are published in the November issue of Cancer Epidemiology,
Biomarkers and Prevention journal.
Other studies have
shown overweight and obesity are risk factors for colon, breast,
kidney and endometrial cancers. This study, sponsored by the National
Cancer Institute, examined the potential link between obesity
and risk of leukemia. Over 14 years, the health of more than 37,000
older Iowa women was monitored; 200 of the women developed leukemia
– 74 were diagnosed with AML and 88 with chronic lymphocytic
leukemia (CLL).
"We found that
the risk for getting AML was 90 percent higher in overweight women
age 55 and older who had a body mass index (BMI*) of 25-29,"
says Julie Ross, Ph.D., associate professor of pediatrics at the
University of Minnesota Medical School. She also is an epidemiologist
at the University of Minnesota Cancer Center and the lead researcher
on this study. "In obese women age 55 and older and with
a BMI of 30 or greater, the risk increased to as much as a 140
percent."
The study found little
evidence of an association between overweight and obesity with
CLL.
AML is cancer that
starts in the bone marrow in immature cells that normally should
become white blood cells. Acute means the leukemia develops quickly.
According to the American
Cancer Society, about 33,400 new cases of leukemia will be diagnosed
in the United Sates this year. About half of those cases will
be acute leukemias. AML is the most common acute leukemia with
about 11,900 patients diagnosed annually; 90 percent of them adults
age 65 and older. About 8,870 people with AML will die this year.
The 5-year survival rate for middle-aged people is about 12 percent
and 3 percent for elderly adults.
While incidence rates
for some adult leukemias, such as CLL and chronic myeloid leukemia,
are declining in the United States, AML in people over age 65
has increased about 10 percent in the last 25 years.
"The fact that
survival rates for AML are extremely poor for older individuals
makes identifying people who are at increased risk for this cancer
of public health importance," Ross says. "Given that
about 65 percent of adults in the United States are overweight
or obese, the projection we can make from our study is that about
30 percent of AML in older adult women could be due to being overweight
or obese."
This study is part
of the Iowa Women's Health Study. In 1986, over 40,000 women between
the ages of 55 and 69 years completed a lifestyle and health questionnaire
that included current height and weight. This study followed more
than 37,000 of these women who, with the possible exception of
skin cancer, were cancer-free at the beginning of the study.
"The risk of AML
was increased among women who reported being overweight or obese
compared with women of normal weight," Ross says. We don't
know why higher BMI would be associated with leukemia, particularly
AML. A possible explanation could be an alteration in hormones
linked with obesity."
She adds that while
it can't be said with research certainty, "it would seem
that as with other cancers linked to obesity, reducing excess
pounds and maintaining normal weight would be important in preventing
AML."
Ross says a limitation
of her study was that only postmenopausal, mostly white, women
participated. She also says BMI was calculated using weight and
height reported by each participant, which could be subject to
some degree of imprecision. However, she notes, BMI is the standard
for population-based studies.
The Cancer Center
at the University of Minnesota is a National Cancer Institute-designated
Comprehensive Cancer Center. The Cancer Center conducts cancer
research that advances knowledge and enhances care. The center
also engages community outreach and public education efforts addressing
cancer. To learn more about cancer, visit the University of Minnesota
Cancer Center Web site at http://www.cancer.umn.edu. For cancer
questions, call the Cancer Center information line at 1-888-CANCER
MN (1-888-226-2376).
* BMI is the measure
of body fat based on height and weight; it is the standard used
for population-based research studies on obesity. As an example,
a 5'4" woman would be considered overweight if she weighed
between 146 and 174 pounds, and obese if she weighed 175 pounds
or more. To calculate body mass index, visit the National Institutes
of Health at http://nhlbisupport.com/bmi/bmicalc.htm.
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