Obesity And Cancer: A Deadly Link
(Washington DC, 5/1/03): The risk of dying from cancer increases significantly
for both men and women who are obese, according to a new study published April
24, 2003 in The New England Journal of Medicine. This increased risk
is shown to affect women more often than men. Being overweight or obese, categories
defined by measuring body mass index (BMI) accounts for roughly 14 percent of
cancer deaths in men and 20 percent of deaths in women, according to the results
of the study.
In this prospective study, researchers from the American Cancer Society examined
the relationship between BMI and death from cancer in more than 900,000 adults.
They found that increased body weight raises the risk of death from all cancers
combined and from cancers at multiple specific sites. In addition, among patients
in the heaviest weight category, with a BMI greater than or equal to 40, the
risk of cancer death was 52 percent higher in men and 62 percent higher in women
when compared with normal weight adults. BMI is calculated by dividing weight
(kilograms) by height (meters) squared.
Women are affected more often than men for several reasons. Many studies have
established a strong association between breast cancer risk and increased body
weight and only a modest association between prostate cancer and obesity. "Obese
women double their risk of breast cancer," according to Dr. Carmen Rodriguez,
MD, MPH Senior Epidemiologist at the American Cancer Society and one of the
authors of the study. Therefore, increased body weight plays a more significant
role among women compared to men suffering from the most common forms of cancer.
In addition, Dr. Rodriguez explains: "the percentage of obese women is
higher than men, 33% versus 28%."
The incidence of obesity in the United States has increased significantly over
the last two decades. According to the Centers for Disease Control and Prevention,
obesity is defined as a BMI greater than or equal to 30. To be classified as
overweight, the BMI is between 25 and 29.9. Recent data from the National Center
for Health Statistics in Hyattsville, Maryland, shows that roughly 31 percent
of the adult population aged 20 years or older meet the criteria for obesity.
And the numbers continue to rise.
While the reasons underlying the association between cancer death and obesity
are not fully understood, female hormones are thought to play a role. "Obesity
increases the risk of breast cancer only among post-menopausal women,"
explains Dr. Rodriguez. Because many post-menopausal breast cancers are stimulated
by estrogen and fat increases circulating hormones in the body, the risk of
cancer increases for obese women.
Obesity has been linked to many serious health conditions, including cardiovascular
disease, diabetes, stroke, and high blood pressure. According to Dr. Rodriguez,
there aren't many studies showing that weight control programs lower the risk
of cancer death: "We can speculate that if you lower your weight, you will
lower your risk as well. But it is not easy to do an observational study with
enough people who have been obese and lower and maintain their weight."
She recommends maintaining a healthy weight as well as good nutrition and exercise
habits throughout life.
Click here for more information on cancer.
The Society for Women's
Health Research is the nation's only not-for-profit organization
whose sole mission is to improve the health of women through research. Founded
in 1990, the Society brought to national attention the need for the appropriate
inclusion of women in major medical research studies and the resulting need
for more information about conditions affecting women. The Society advocates
increased funding for research on women's health, encourages the study of sex
differences that may affect the prevention, diagnosis and treatment of disease,
and promotes the inclusion of women in medical research studies. Dr. Donnica
Moore has been a member of the Society since 1990 and is a past member of its
Board of Directors.
Created: 5/1/2003  - Jennifer Wider, M.D.
Reviewed: 5/1/2003  - Donnica Moore, M.D.