THURSDAY, Sept. 9 (HealthDay News) -- Here's yet another reason
to avoid obesity throughout your life: Doing so may improve your
chances of survival if you're diagnosed with colon cancer.
Women past menopause who are obese and diagnosed with colon
cancer appear to face a greater risk of dying from all causes than
those who are at a healthy weight or merely overweight, a new study
And trying to lose weight after the diagnosis may be too late,
researchers cautioned. Abdominal obesity even prior to the
diagnosis of colon cancer was associated with an increased risk of
dying after contracting the disease, according to study author Anna
Prizment, a postdoctoral fellow at the University of Minnesota
Masonic Cancer Center, in Minneapolis.
Body shape may play a role as well.
Women with the disease who have an unhealthy waist-to-hip ratio
and a large waist are at increased risk of death, Prizment
The study is published in the September issue of
Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.
Colon cancer is the second leading cause of cancer-related death
among women and men combined. It is expected to kill more than
51,000 people -- including nearly 25,000 women -- in the United
States in 2010, according to the American Cancer Society.
Many studies have found a link between excess body weight and a
higher risk of colon cancer. "But not so many studies have examined
how obesity affects survival of the colon cancer patient," Prizment
So, with her colleagues, she evaluated women who had
participated in the Iowa Women's Health Study, focusing on 1,096
women participants who were diagnosed with colon cancer between
1986 and 2005. Body and weight measurements were obtained before
the colon cancer diagnosis.
The study was retrospective, meaning that the data used had been
recorded for reasons other than research.
During the follow-up period of up to 20 years, 493 women died.
Among this group, colon cancer was the underlying cause in 289
Obese women -- those with a body-mass index (BMI) of 30 or
higher -- had a 45 percent increase in all causes of death compared
to women with a healthy weight, according to Prizment. Their risk
of dying from colon cancer also climbed by 32 percent compared to
healthy weight women, but that finding was not significant from a
statistical point of view. However, the 45 percent increase in all
causes of death was clinically significant.
The researcher also found that the risk of dying was higher
among underweight women, those with a BMI below 18.5. "But we don't
want to talk much about them because we had too few of them,"
Prizment expanded on the unhealthy waist-to-hip ratio and large
waist associations that she found were associated with a higher
risk of dying from colon cancer.
A waist-to-hip ratio of 0.80 or below for women is considered
low-risk. For instance, a woman with a waist of 27 inches and hips
of 36 inches has a waist-to-hip ratio of .75.
Women with waists of 37.5 inches or higher had a higher death
risk than those with a healthier waist size, she found.
Exactly why the obese women with unhealthy waist-to-hip ratios
and big waists are at increased risk of death from colon cancer
compared to slimmer women isn't known. "They may be diagnosed at an
advanced stage," Prizment said. "They may have less access to
health care. There could be a direct biological mechanism."
Her advice for women? "Maintain a healthy body weight is the
only recommendation we can give for all postmenopausal women," she
Until the new study, findings about excess body size in colon
cancer patients and risk of death have been mixed and conflicting,
said Dr. Peter Campbell, director of the tumor repository for the
American Cancer Society.
One strength of the new study, he said, is that "body size was
measured before they had the diagnosis." Measuring after diagnosis
may not give a true picture, he said, as weight loss can occur
after the diagnosis.
"It's lifelong body size that's important [to know in gauging risk]," he said. "This study adds important new information to our understanding of body size and health."
He agreed with Prizment that the finding underscores the
importance of maintaining a healthy body weight with age.
To learn more about colon cancer, visit the
American Cancer Society.
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