A Justice Site
Mirror Sites:
CSUDH - Habermas - UWP - Archives
California State University, Dominguez Hills
University of Wisconsin, Parkside
Soka University Japan - Transcend Art and Peace
Created: April 24, 2003
Latest Update: April 24, 2003
jeannecurran@habermas.org
takata@uwp.edu
Backup of Researchers Point to Cancer's Links to Obesityhttp://www.latimes.com/news/science/la-sci-obese24apr24,1,5221041.storyResearchers Point to Cancer's Links to Obesity
By Thomas H. Maugh II
Times Staff Writer6:55 PM PDT, April 23, 2003
Obesity plays a much bigger role in causing cancer than researchers had previously believed, accounting for 14 percent of cancers in men and 20 percent in women, according to a massive new study by the American Cancer Society.
An estimated 90,000 Americans die each year of cancer caused primarily by obesity and excess weight, according to the study, published Thursday in the New England Journal of Medicine. That makes weighing too much second only to smoking -- which causes about 170,000 cancer deaths per year -- as a preventable cause of cancer.
The team studied more than 900,000 people nationwide for 16 years to provide the first definitive understanding of the role of obesity in causing cancer. With only a few exceptions, being overweight increases the risk of virtually every form of cancer and, the more overweight you are, the greater the risk.
Men in the highest weight groups were 52 percent more likely to die from cancer than those of normal weight, while women in the highest weight groups were 62 percent more likely to die from it.
"Many of us had believed that these relationships were present before, but they have never been so clearly shown," said Dr. Robert J. Mayer of the Dana Farber Cancer Institute in Boston. "This is an epidemiological landmark."
Researchers have only a limited understanding of what causes the excess cancers. Fat tissue, for example, leads to an overproduction of estrogen and other steroid hormones that play a crucial role in breast and other endocrine-related cancers. Obesity also leads to excess insulin production and an increase in insulin-like growth factor receptors, which have previously been associated with cancer.
Obesity is also linked to gastroesophageal reflux -- the eruption of stomach acids into the esophagus. That, in turn, has been shown to increase the rate of various esophageal cancers, whose incidence has grown tremendously over the past two years. But scientists still have much to learn about the biological links, said Dr. Eugenia E. Calle of the cancer society, who led the study.
In addition to causing cancers, obesity also exacerbates their effects. The obese are often reluctant to visit doctors, either because of shame or simple difficulties in traveling for appointments. Detection of cancers is often more difficult in the obese because they are obscured by excess tissues, and treatment can be a problem because fat absorbs chemotherapeutic drugs.
An estimated 30 percent of Americans are considered obese and another 35 percent are considered overweight. Previous studies have suggested that 11 percent of deaths from heart disease in men and 14 percent of cases in women are caused by obesity alone. Additionally, excess weight also causes diabetes -- with its panoply of side effects -- arthritis, strokes and other medical problems.
"This study makes clear that, now that we are smoking less, morbid obesity represents another major problem that we as a society need to deal with," Mayer said.
"Hopefully, this will spur weight control as a national priority," Calle added. The participants in the study were drawn from the 1,184,617 volunteers enrolled in the Cancer Prevention Study II, begun in 1982.
Calle and her colleagues eliminated those volunteers who had lost more than 10 pounds in the year before the study began, those who already had cancer, and those for whom information on race or smoking history was not available.
That left 404,576 men and 495,477 women. Their average age at the beginning of the study was 57. Over the 16 years of the study, 32,303 of the men and 24,842 of the women died from cancer.
For women, the team concluded that deaths from uterine cancer were six times more common among the heaviest women, those from kidney cancer were nearly five times more common, those from cervical cancer were three times more common, and those from breast, gallbladder, pancreas and esophageal cancers were more than twice as common.
Among the heaviest men, deaths from liver cancer were more than six times as common, those from pancreatic cancer were more than twice as common, and those from gallbladder, stomach and colorectal cancer were 75 percent more common.
Among the very few cancers that were not found to be related to excess weight were brain, bladder and skin cancers.
Calle said that scientists are only now becoming aware of the great risks associated with excess weight, just as they were becoming aware of the risks associated with smoking some 35 years ago. "It took a long time to create large changes in the smoking rates," she said, and it will probably take a similar amount of time to affect eating problems.
The following paragraph is in the print version of the paper, but missing in the online version.
"We have in the past considered this a problem of individuals," she said. "While individuals do have choices to make, in terms of food and physical activity, there are other levels of concern in terms of policy, cultural norms, and what we do in schools and the workplace. Right now, we have environments that make it difficult for people to be physically active, and that makes it very easy to eat large portions of hig-calorie foods."