Obesity-related cancer burden on the rise
The world has seen a steady rise in the prevalence of excess body weight and the associated cancer burden over the past four decades, according to a study. The number of obese adults has grown sixfold from 100 million in 1975 to 671 million in 2016, with obesity accounting for about 3.9 percent of all cancers in 2012 globally.
Between 1975 and 2016, obesity increased by ninefold in men (30.7 to 281 million) and by more than fivefold in women (69.3 to 390 million). The largest absolute increase was reported among men and boys in high‐income Western countries and among women and girls in Central Asia, the Middle East and North Africa. [CA Cancer J Clin 2018;doi:10.3322/caac.21499]
“The global obesity burden shifted from predominantly high-income Western countries and Central and Eastern Europe in 1975 to more diverse regions in 2016. Most notably, East and South-Eastern Asia accounted for 3 percent of the world’s obese men and women in 1975 but for 15–17 percent in 2016, reflecting population growth and extended longevity, as well as increased obesity prevalence,” the authors pointed out.
“Nevertheless, high-income Western countries remained the largest contributor to the global obesity burden in 2016 among both men (33 percent) and women (26 percent),” they added.
While national wealth emerged as the most evident systematic driver of population obesity, the concurrent rise in excess body weight in almost all countries was said to be driven mainly by changes in the global food system, along with reduced opportunities for physical activity.
Such changes involved the overconsumption of calories (ie, increases in both food portion size and the supply of affordable, palatable, energy-dense, ready-to-eat food), widespread use of sweetening agents, and improved distribution systems to make unhealthy food much more accessible and convenient. [J Am Diet Assoc 2003;103:231-240; Am J Clin Nutr 2004;79:537-543]
Cancer burden attributable to obesity
In 2012, excess body weight accounted for approximately 544,300 cases or 3.9 percent of all cancers, with the proportion varying from <1 percent in low‐income countries to 7–8 percent in some high‐income Western countries and in Middle Eastern and Northern African countries.
The attributable cancer burden was more than double for women than for men (368,500 vs 175,800 cases). Breast cancer was the greatest contributor to all cancer cases in women (114,800 cases or 31 percent), followed by endometrial cancer (98,400 cases or 27 percent) and colorectal cancer (42,300 cases or 12 percent). In comparison, liver cancer was the biggest contributor in men (54,600 cases or 31 percent), followed by colorectal cancer (42,200 cases or 24 percent) and kidney cancer (37,400 cases or 21 percent).
Close to one-half of obesity-related cancer cases occurred in high-income Western countries (252,500 cases or 46 percent), pointing to both a higher prevalence of excess body weight and higher incidence rates for many cancers attributable to obesity.
The East and South-Eastern regions of Asia, even with a relatively low prevalence of elevated BMI, hold the second largest share (87,600 cases or 16 percent) due to the large population and high burden of liver cancer. Central and Eastern Europe had the third largest share (77,700 cases or 14 percent), followed by Latin America and the Caribbean (9 percent), and Central Asia, the Middle East and North Africa (6 percent).
“Given the pandemic proportion of excess body weight in high‐income countries and the increasing prevalence in low‐ and middle‐income countries, the global cancer burden attributable to this condition is likely to increase in the future,” the authors noted.
Addressing the growing global burden
“The rapid increase in both the prevalence of excess body weight and the associated cancer burden highlights the need for a rejuvenated focus on identifying, implementing and evaluating interventions to prevent and control excess body weight,” they said.
Evidence-based and cost-effective strategies to prevent and control obesity encompass the promotion of a healthy diet and physical activity through collaborative action by governments and stakeholders (eg, nongovernmental organizations and private sector). This approach is said to overcome the strong commercial forces seeking to profit from the overconsumption of nutrient-low, palatable foods. [Lancet 2015;385:2400-2409; Lancet 2015;385:2410-2421]
“Finally, whereas population-level efforts should be an area of focus, they should be matched with enhancing access to healthcare interventions for weight management, including screening for and management of excess body weight as a means of secondary intervention,” the authors said.