Fall 2012

Defusing obesity’s role in cancer

Dr. Larry Corey, President and Director

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This edition of Quest highlights an important and difficult issue in the world of cancer research: how obesity influences cancer. Many epidemiological studies have shown that obesity increases cancer risk. That includes colorectal cancer, breast cancer and certain prostate cancers.

Being overweight or inactive is also linked to cancers of the esophagus, pancreas, kidney, thyroid and gallbladder. Like all such risk factors, the link is not absolute for persons with a high body mass index. However, one study found that the heaviest patients—those with a BMI of at least 40—had cancer death rates 52 percent higher for men and 62 percent higher for women. About 17 percent of all breast cancers, nearly 33,000 cases per year, are attributed to excess body fat; for colorectal cancer, it’s 9 percent, or 13,200 cases per year.

While these numbers may seem relatively small, the epidemic of obesity is increasing in our country. The National Cancer Institute projects obesity will lead to about 500,000 new cases of cancer in the U.S. by the year 2030. Unfortunately, the American lifestyle is extending globally, with sedentary lifestyles becoming prevalent throughout the world. Some studies suggest that obesity is associated with a higher mortality around the world than smoking.

This is why the work of our cancer prevention researchers is so important. We study obesity because our mission is to prevent, detect and treat cancer and other life-threatening diseases. We have assembled a top team of researchers who want to understand—and defuse—obesity’s role
in cancer.

Our world-leading researchers have conducted exacting studies for many years on nutrition and exercise and their relation to cancer risk. And they have produced many landmark studies linking exercise to cancer risk-factor reduction. They have also shown that exercise positively affects prognosis and quality of life in cancer survivors.

While we ultimately want to understand the mechanism by which weight gain causes a genetic disease like cancer, our research teams are much more pragmatic as they attempt to define strategies to reduce this risk. At the Center, Dr. Mario Kratz and his colleagues study hormones, insulin and the role of inflammation as cancer-risk triggers.

Kratz is particularly interested in inflammation. In some obese people, the tissue gets inflamed and stays that way as long as they remain obese. Kratz believes that understanding what contributes to inflammation will help us understand the link between obesity and cancer and other diseases, such as diabetes and cardiovascular disease.

Recently, Dr. Anne McTiernan, from our Public Health Sciences Division, found that postmenopausal overweight or obese women who lost weight through a reduced calorie diet significantly lowered their levels of certain types of estrogen, testosterone, inflammation indicators and insulin—limiting their cancer risk.

Better nutrition and more exercise certainly have proven to be important components in reducing cancer risk. But our researchers also are studying what physiological factors are triggered by obesity that leads to increases in cancer risk.

The research conducted by McTiernan, Kratz and colleagues is often made possible by study volunteers. We feature one of them in this issue of Quest. Sally von Bargen signed up for one of our studies and lost 75 pounds in one year.

We hope that you will partner with us to continue funding this important research so we can better understand obesity’s links to cancer and develop effective strategies to alter the risk. If you are interested in donating to this endeavor, please contact the Hutchinson Center at (206) 667-4399 or (800) 279-1618.


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