Excess body weight is responsible for about 4 percent of all cancer cases worldwide and an even larger proportion of malignancies diagnosed in developing countries, a recent study suggests.
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 and brain and spinal cord.
More recently, some research has also tied excess weight to risk for prostate tumors as well as cancers of the mouth and throat.