Obesity raises risk of death from cancer

April 23, 2003 at 6:00 PM
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ATLANTA, April 23 (UPI) -- Obesity appears to increase the risk of dying from cancer significantly and could play a role in more than 90,000 deaths from the disease each year in the United States, a study by the American Cancer Society released Wednesday reveals.

The study, which looked at hundreds of thousands of people over a 16-year period, found "the heaviest men and women in the study had 50-60 percent higher death rates from cancer than normal-weight people," Jeanne Calle, the principal author of the study and director of analytic epidemiology for the American Cancer Society, told United Press International.

Based on the results, Calle's team used the current prevalence of obesity in the United States to estimate "as much as 20 percent of cancer deaths in women and 14 percent in men" could be due to being overweight.

"This translates to more than 90,000 deaths from cancer each year that could potentially be avoided if we could maintain normal weight throughout adulthood," Calle said.

Previous studies have indicated obesity could worsen the outcome or increase the likelihood of developing some cancers, so the current findings, which appear in the April 24 issue of The New England Journal of Medicine, were not entirely unexpected.

However, the researchers were surprised to find obesity seemed to impact nearly all types of cancer. The increased risk held true for all cancers combined and the study found associations between obesity and some cancers that had not been seen before, Calle said.

"This certainly suggests the number of cancer sites that obesity contributes to may be greater than previously thought," she said.

Dr. Hans-Olav Adami of the Karolinska Institutet in Stockholm, Sweden,who wrote an accompanying editorial to the study, told UPI the findings "add to the growing evidence that obesity, following tobacco smoking, is the second ... most preventable cause of cancer incidence and mortality."

In addition, Adami said, the results "add to the list of short- and long-term consequences of obesity and is yet another reason to, by all means, prevent the epidemic" of overweight Americans and people in a growing list of other countries as they adopt a more sedentary lifestyle that provides easy access to calorie-rich foods.

In the study, Calle's team identified 900,000 U.S. adults who were free of cancer in 1982 and tracked them for 16 years. The study participants ranged in weight from normal weight to severely obese.

There were more than 57,000 deaths from cancer among the study group over the 16-year study period. Those who were most overweight had death rates from all cancers combined that were 52 percent higher for men and 62 percent higher for women than their normal-weight counterparts.

Being overweight was associated with higher rates of death for specific cancers, including cancer of the esophagus, colon, liver, gallbladder, pancreas, kidney, non-Hodgkin's lymphoma and multiple myeloma.

The risk of death held true even after accounting for smoking, education, race and other factors known to play a role in causing cancer.

The study did not attempt to address why obesity seems to worsen cancer outcomes but Galle said other studies have indicated overweight people tend to have higher circulating levels of certain hormones, such as estrogen and insulin, that "could contribute to causing and or promoting cancer growth."

Both Galle and Adami agreed the results suggest a need for increased emphasis and perhaps a different strategy on addressing the high rates of obesity in the United States.

"Weight control is going to have to become a national priority in the same way that smoking cessation has become a national priority," Galle said.

It could require making significant changes at the policy and societal level, she said. "Significant public health changes usually come from changing public policies and social norms," she added. This would include attempting to create an environment in which individuals find it easier to make healthy choices, such as access to foods that are not so calorie-rich and increasing levels of exercise.

Adami was more pessimistic.

"This is an enormous concern (and) I'm not sure we have any promising strategies to counteract this epidemic," he said, noting "tackling obesity has been enormously unsuccessful."

However, he noted obese children tend to stay obese in their adult-years so one strategy that might prove beneficial is initiating prevention efforts earlier in life.

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(Reported by Steve Mitchell, UPI Medical Correspondent, in Washington)

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