Growing prevalence of excess body weight increasing global cancer burden
The increasing prevalence of excess body weight, which was responsible for approximately 3.9% of all cancers worldwide in 2012, is driven by multiple economic and environmental factors and should be addressed through policy actions and other interventions, according to a report published in CA: A Cancer Journal for Clinicians.
“Between 1975 and 2016, the prevalence of excess body weight in adults — defined as a BMI of 25 kg/m2 or greater — increased from nearly 21% in men and 24% in women to approximately 40% in both sexes,” Hyuna Sung, PhD, principal scientist of the surveillance and health sciences research program at American Cancer Society, and colleagues said. “Notably, the prevalence of obesity quadrupled in men, from 3% to 12%, and more than doubled in women, from 7% to 16%.”
Those increases, along with worldwide population growth, led to a more than a 6-fold global rise in the number of obese adults, from 100 million to 671 million. Men and boys in high-income Western countries showed the largest absolute increase in obesity, as well as women and girls in Central Asia, the Middle East and North Africa, Sung and colleagues noted.
The researchers outlined possible drivers of population-level obesity. These include systemic factors, such as policy and economic systems that encourage high growth and consumption; environmental factors, such as food supply and the marketing of high-calorie, low-nutrient foods; behavioral patterns, such as insufficient physical activity; and genetic predisposition to excess weight.
Increasing national wealth also has fueled shifts in demographics, technological advances and changes in nutrition — such as more processed foods — that are conducive to obesity.
The researchers pointed out, however, that economic growth is not necessarily associated with excess body weight. They cited high-income Asian Pacific countries with a low prevalence of obesity (range, 4%-7%), which is likely attributable to traditional lower-calorie diets and transportation systems that involve walking. Conversely, high rates of obesity are seen in certain lower-income countries, such as some Pacific Island nations (range, 40%-65%) and Egypt (women, 43%; men, 24%).
The obesity trend has taken a toll on health, resulting in an estimated 4 million deaths in 2015 and illnesses that carried an economic impact of $2 trillion in 2014, researchers wrote.
Moreover, approximately 3.9% of all cancers (544,300 cases) in 2012 were linked to excess body weight, with percentages varying from less than 1% in low-income countries to 7% or 8% in high-income Western nations and Middle Eastern and North African countries.
A report from the International Agency for Research on Cancer Working Group on Body Fatness states that adequate evidence exists to make a causal association between excess body weight and increased risk for 13 cancers. Worldwide in 2012, excess body weight accounted for approximately:
- 7% of all postmenopausal (aged 50 years and older) breast cancers (114,800 cases);
- 7% of colorectal cancers among women (42,300) and 6% (42,200) among men;
- 31% of endometrial cancers (98,400);
- 30% of esophageal adenocarcinomas (11,300);
- 13% of gallbladder cancers among women (13,000) and 10% (7,400) among men;
- 20% of kidney cancers (25,200 women, 37,400 men);
- 10% of liver cancers among men (54,600) and 14% (30,200) among women;
- 36% of meningioma cases;
- 7% of multiple myeloma cases among women (4,500) and 9% (4,400) among men;
- 4% of ovarian cancers (9,100);
- 6% of pancreatic cancers among men (10,300) and 7% (11,200) among women;
- 9% of stomach cancers among men (6,400) and 11% (2,900) among women, and
- 7% of thyroid cancers among men (14,800) and 6% (3,900) among women.
Additionally, overweight has been labeled a probable cause of advanced prostate cancer and cancers of the mouth, pharynx and larynx, according to a press release.
Women have been found to have a higher cancer burden attributable to excess body weight than men (368,500 vs. 175,800 cases).
Controlling global rates of obesity is one of nine key initiatives WHO is undertaking to reduce the burden of cancer and other noncommunicable diseases. The organization is calling for interventions such as legislation to ban trans fats, taxes on sugar-sweetened beverages, limits on food portion and package sizes, and improved access to public transportation and open space for walking and cycling.
The rapid increase in both the prevalence of excess body weight and the associated cance rburden highlights the need for a rejuvenated focus on identifying, implementing,
and evaluating interventions to prevent and control excess body weight,” the researchers wrote. – by Jennifer Byrne
Disclosures : Sung reports employment with American Cancer Society. Please see the study for all other authors’ relevant financial disclosures.