Obesity Raises Cancer Risk

By Amanda Gardner
HealthDay Reporter
Friday, February 15, 2008; 10:00 AM

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FRIDAY, Feb. 15 (HealthDay News) -- The more weight you carry on your body, the greater your odds of developing cancer, British researchers report.

This is true not only of fairly common cancers such as colon and breast, but also of lesser known varieties, including gallbladder. Moreover, the degree of risk differs between men and women and among different ethnic groups, report the authors of a comprehensive new paper appearing in this week's issue of The Lancet.

"This is a profoundly important issue. Obviously, the obesity epidemic is a huge problem itself, and the relationship to cancer is only one of the many adverse health effects of being overweight and obese," said Dr. Michael Thun, head of epidemiological research at the American Cancer Society. "The evidence has been accumulating now for over 10 years. . . This study tries to provide a quantitative measure of how much the relative risk goes up with each increment, basically jumping from one BMI [body-mass index] category to another."

Although extra fat has already been identified by research as a risk factor for several different types of cancer, Thun said, "the problem of obesity is so large and so difficult to solve that there's a very sound reason for ongoing studies of things that have become increasingly well-known, just because it helps the momentum in stimulating approaches that will actually help people maintain a healthy weight."

Last year, a report issued by the American Institute of Cancer Research and the U.K.-based World Cancer Research Fund concluded that body fat is associated with an increased risk for several different types of cancer including esophageal adenocarcinoma, as well as cancers of the pancreas, colon and rectum, breast (postmenopausal), endometrium and kidney.

Although that report was one of the most comprehensive to date, it did leave some questions unanswered. For instance, are there associations between less common cancers and body weight, and do the associations differ between the sexes and people of different ethnic backgrounds?