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Cancer
News | The American Institute for Cancer Research | September
29, 2006
Body fat works to
raise cancer risk
By The
American Institute for Cancer Research
(Dubai Health & News) New research findings show that extra
body fat doesn't just weigh you down. Scientists now have evidence that
too many fat cells prompt ongoing reactions in the body that may
increase cancer risk.
If Elizabeth Platz, Sc.D., Assistant Professor of Epidemiology at Johns
Hopkins University, and her colleagues are right, excess fat may alter
the body's basic functioning in ways that raise risk for cancer and
other diseases.
Research has already shown that obesity boosts levels of hormones such
as estrogen, for example, which increase risk for breast cancer in
post-menopausal women. Too much body fat, especially in the abdomen,
also increases insulin resistance, priming the body for diabetes.
Now, recent findings by Dr. Platz and her research team suggest that
obesity, especially around the waist, may also influence the body's
inflammatory response so that risk for colon cancer is higher.
Too Much of a Good Thing
Inflammation is the body's first response to infection or injury. It's
essential to healing, but it can go awry. Many scientists suspect that
chronic low-level inflammation of body tissues underlies a lot of
disease processes. How does this happen?
Substances called cytokines are part of the body's inflammation response
to help with fighting infection and healing wounds. Cytokines are made
by white blood cells, but fat cells can make cytokines too.
"In addition to fighting infection, cytokines help with wound
repair by stimulating tissue growth," explains Dr. Platz. "Our
research suggests that when the body has an oversupply of fat cells,
those cells release too many cytokines. This boosts the body's
inflammatory response and causes damage to cells and their DNA."
"Where there is genetic damage plus stimulation for cells to grow,
the chance of cells growing out of control and becoming cancer is
increased," she says.
A Link to Diabetes and Cancer
In a previous study, funded in part by American Institute for Cancer
Research (AICR), Dr. Platz and her colleagues showed that people who
were obese (with a body mass index of 30 or higher) had a higher risk of
colon cancer. People who were diabetic or had poor glucose control also
had increased risk.
What's more, a follow-up study, also supported in part by AICR, found
that people who had elevated blood levels of a protein called CRP (or
C-reactive protein) also had a higher risk of colon cancer. CRP is a
marker for the presence of low-level inflammation somewhere in the body.
Some cancers are known to be associated with persistent inflammation
that's related to chronic infection. For example, people infected with
one of the viruses that cause hepatitis are more susceptible to liver
cancer. Chronic infection with Helicobacter pylori, a bacterium that
lives on the lining of the stomach, increases risk for stomach cancer.
People with inflammatory bowel disease have above-average rates of colon
cancer.
The idea that fat cells could be actively involved in promoting
inflammation is a relatively new one, says Dr. Platz. "There is
more to being fat than carrying around excess weight. People should
begin thinking of excess body fat as actively harmful to their
health."
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