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Researchers are only just beginning to understand how obesity impacts the development of cancer, but one thing is sure — it is one of the major risk factors for the rising incidence of the disease.

SALT LAKE CITY — Researchers are only just beginning to understand how obesity impacts the development of cancer, but one thing is clear — it is one of the major risk factors for the rising incidence of the disease.

"Obesity is increasing dramatically worldwide … we urgently need to identify the specific mechanisms that link obesity to cancer," said Cornelia M. Ulrich, senior director of Population Sciences at the Huntsman Cancer Institute at the University of Utah. Her research typically focuses on lifestyle and biological factors in cancer prevention and prognosis.

Ulrich recently led a group of researchers in a literature review, analyzing materials dating back to 1946, that shows several ways that fat contributes to cancer growth.

Obesity can increase the risk of inflammation in the body, which has long been associated with cancer, according to the research published in the September issue of Cancer Prevention Research, a journal of the American Association for Cancer Research. Obesity is also said to affect how cancer grows and/or spreads in the body, depending on the type of fat and where it is located. And fat also affects a person's immune response to disease.

Previous research indicates that obesity is a primary risk factor for many types of cancer, including colorectal, postmenopausal breast, liver, endometrial, esophageal, kidney, gastric, gall bladder, pancreatic, ovarian, thyroid and multiple myeloma cancers, according to Ulrich's study. Interactions between tumors that result from those cancers and the surrounding environment in the body may point to better prevention techniques.

And while researchers agree that obesity definitely impacts cancer development, little is known about how. Ulrich's research, however, shows that there is some type of communication or reaction, called "crosstalk," between cells and different types of fats in the body.

For example, different types of fats (white, brown and beige), located deep in the body or just under the skin, can help cancer cells grow or spread depending on proximity to the diseased cells.

"The more we understand this process, the better we can identify targets and strategies for decreasing the burden of obesity-related cancer," Ulrich said.

In the United States, 38 percent of adults are obese and nearly 8 percent are extremely obese, according to the Journal of the American Medical Association. Those numbers continue to climb, and for many people, losing excess adipose tissue or fat is extremely challenging, the review notes.

Ulrich said her study and previous research supports the importance of maintaining a healthy body weight. And even slender people may have fats hiding around internal organs posing a risk, she said.

Healthy diets and exercise that includes strength training to build lean muscle mass can help fight the development of excess fat, Ulrich added.

She said more research is needed to further understand the link between obesity and cancer.