University Of Pittsburgh Researchers Demonstrate Metabolic Link Between Large Waists And Colorectal Cancer
PITTSBURGH, Jul 15, 1999 /PRNewswire via COMTEX/ -- People with large
waistlines suffer metabolic changes that significantly predispose them
to developing colorectal cancer, according to new data from a
University of Pittsburgh-led study whose results are published in the
July 7 issue of the Journal of the National Cancer Institute. This
information is the first to link intra-abdominal fat, or visceral
adipose tissue (VAT), and its associated metabolic changes with
colorectal cancer, according to the authors.
"For several years, scientists have recognized that obese people
aremore likely to develop colorectal cancer. Our study sheds light on
the metabolic process underlying this connection," said Robert Schoen,
M.D., assistant professor of medicine at the University of Pittsburgh
School of Medicine, where he is the medical director of the Center for
Families at Risk for Colorectal Cancer. "The metabolic parameters we
measured, including glucose, insulin and waist circumference, reveal a
risk of colorectal cancer that equals or exceeds other known risk
factors, such as having a first-degree relative with this disease or
consuming a high-fat or low-fiber diet."
The current report is based on a study of 5,849 people age 65 and older
who participated in the Cardiovascular Health Study, a multi-center
observational study of risk factors for coronary heart disease and
stroke. The researchers found that people with increased waistlines,
high levels of glucose (the sugar needed to fuel the body's activities)
and high levels of insulin (the hormone that helps dispose of glucose)
were twice as likely to develop colorectal cancer as individuals
without these characteristics. Individuals in the study who developed
colorectal cancer did not differ from their non-affected counterparts
in terms of smoking, current aspirin use, alcoholic drinks consumed per
week, percent of fat calories in diet or mean number of vegetable or
fruit servings per week. Study participants were followed for an
average of 6.5 years.
"A very important finding here is that people with increased amounts of
abdominal obesity, or VAT, do not need to be diabetic to develop
colorectal cancer," remarked Lewis Kuller, M.D., Dr.P.H., chairman of
the department of epidemiology at the University of Pittsburgh Graduate
School of Public Health and study co-investigator. "Nondiabetics appear
to have an elevated risk of colorectal cancer as their fasting insulin
and glucose rise, even if glucose levels do not reach those defined as
consistent with diabetes."
Previous studies have shown that insulin and insulin-like growth
factors (IGFs) stimulate the growth of colorectal cancers. Obesity
appears to decrease the production of proteins that bind with
circulating IGFs, thus exposing the body to higher concentrations of
these substances. More research is needed to clarify the roles VAT,
insulin, IGF and IGF-binding factors play in causing colorectal cancer,
according to the investigators.
Other researchers on the federally funded study include Catherine M.
Tangen, Ph.D., department of biostatistics, University of Washington,
Seattle; Gregory L. Burke, M.D., department of public health and
sciences, Wake Forest University School of Medicine, Winston-Salem,
N.C.; Mary Cushman, M.D., departments of medicine and pathology,
University of Vermont, Burlington; Russell P. Tracy, Ph.D., departments
of medicine, pathology and biochemistry, University of Vermont; Adrian
Dobs, M.D., department of medicine, The Johns Hopkins University,
Baltimore, Md.; and Peter J. Savage, M.D., National Heart, Lung and
Blood Institute, Bethesda, Md.
