As of 2012, excess body weight accounted for approximately 544,300
cancers diagnosed annually around the world, researchers report in
CA: A Cancer Journal for Clinicians. While overweight and obese
individuals contributed to just 1 percent of cancer cases in
low-income countries, they accounted for 7 to 8 percent of cancers
diagnosed in some high-income Western countries and in Middle
Eastern and North African nations.
"Not many people know about excess body weight and its link to
cancer," said lead study author Hyuna Sung of the American Cancer
Society in Atlanta.
"Trying to achieve healthy weight and maintaining it is important
and may reduce the risk of cancer," Sung said by email.
But the proportion of people who are overweight and obese has been
increasing worldwide since the 1970s, the researchers note. As of
2016, 40 percent of adults and 18 percent of school-age children
were overweight or obese, for a total of almost 2 billion adults and
340 million kids worldwide.
While the proportion of people with excess body weight has increased
rapidly in most countries and across all population groups, the
surge has been most pronounced in some low- and middle-income
countries that have adopted a Western lifestyle with too little
exercise and too many unhealthy foods, the study team writes.
"The simultaneous rise in excess body weight in almost all countries
is thought to be driven largely by changes in the global food
system, which promotes energy-dense, nutrient-poor foods, alongside
reduced opportunities for physical activity," Sung said.
Overweight and obesity has been definitively linked to an increased
risk of 13 cancers affecting the breast, colon and rectum, uterus,
esophagus, gallbladder, kidney, liver, ovary, pancreas, stomach, and
thyroid, brain and spinal cord, and blood cells.
More recently, some research has also tied excess weight to risk for
prostate tumors as well as cancers of the mouth and throat.
National wealth is the most apparent systematic driver of population
obesity, the study authors note.
The economic transition to a wealthier economy brings with it an
environment that precipitates obesity; each $10,000 increase in
average per capita national income is associated with a 0.4 increase
in body mass index among adults, the study authors note.
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However, obesity is uncommon in some high-income Asia-Pacific
countries, which is likely a result of consuming healthier foods
like lean fish and veggies and eating fewer calories, as well as
active transportation and walking as part of daily activity, the
authors point out.
Still, the report offers fresh evidence of the need for policies
that promote healthy eating and exercise habits as a way to battle
obesity and reduce the global burden of cancer, the authors argue.
Dietary interventions might include eliminating trans-fats through
the development of legislation to ban their use in the food chain;
reducing sugar consumption through effective taxation on
sugar-sweetened beverages; implementing subsidies to increase the
intake of fruits and vegetables; and limiting portion and package
size to reduce energy intake and the risk of excess body weight.
Activity interventions might include encouraging urban planning that
promotes high-density housing with sidewalks, accessible public
transportation and widespread availability of open spaces, parks and
places to walk and cycle.
"Based on cancer alone, this report makes the case for allotting
significant resources to addressing the global obesity epidemic, and
those efforts have to address multiple factors that are creating 'obesigenic'
societies," said Dr. Graham A. Colditz of Washington University
School of Medicine in St. Louis.
"The actions of individuals are important when it comes to weight -
eating a healthy diet and exercising regularly, for example,"
Colditz, who wasn't involved in the report, said by email. "But
unless those actions are supported by policies, infrastructure,
schools, and employers, they're less likely to take hold and be
broadly successful over time."
SOURCE: https://bit.ly/2QvwrJV CA: A Cancer Journal for Clinicians,
online December 12, 2018.
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