09 Jan 2019
Study: obesity linked with 13 common cancers globally
BY Tom Walker
Obese people have an increased risk of developing 13 types of cancer – and the threat is greatest in developed nations with sedentary populations.
The finding comes from a report published in the American Cancer Society's A Cancer Journal for Clinicians publication, which collected and studied datasets from around the world.
Titled Global patterns in excess body weight and the associated cancer burden, the study concludes that obesity is a leading factor in around 4 per cent of all worldwide cancer cases.
The study cites a report from the International Agency for Research on Cancer Working Group on Body Fatness in 2016, which concluded that there is "sufficient evidence" to link body fatness with the risk of 13 cancers – including breast cancer in women and colon, rectum, oesophagus, kidney, liver and stomach (cardia) cancer in both genders.
The total number of cancer cases attributable to excess body weight was more than twice as high in women (368,500 cases) as in men (175,800 cases).
Breast cancer was the largest contributor (114,800 cases or 31 per cent) among women, followed by endometrial cancer (98,400 cases or 27 per cent) and colorectal cancer (42,300 cases or 12 per cent).
In contrast, the largest contributor among men was liver cancer (54,600 cases or 31 per cent), followed by colorectal cancer (42,200 cases or 24 per cent) and kidney cancer (37,400 cases or 21 per cent).
Geographically, it is developed countries which seem to have the highest rates of cancers with a potential link to obesity.
Almost one half (46 per cent) of cancer cases attributable to excess body weight occurred in high-income, developed (or "Western") countries, reflecting both higher prevalence of excess body weight and higher incidence rates for many obesity‐related cancers.
Despite a relatively low prevalence of excess body weight, the East and South‐Eastern Asia region had the second largest share (87,600 cases or 16 per cent) – which the researchers attribute to its large population and high burden of liver cancer.
Central and Eastern Europe had the third largest share (or 14 per cent), followed by Latin America and the Caribbean (9 per cent), and Central Asia, the Middle East, and North Africa (6 per cent).
The study also outlines some of the reasons for obesity in modern societies.
"Built environments and transportation systems influence opportunities for physical activity, and consequently body weight," the report reads.
"A study conducted in eight provinces in China demonstrated that the likelihood of being obese was 80 per cent higher for men and women in households that owned a motorised vehicle, compared with those that did not own a vehicle.
"An international study showed that adults in the most activity‐supportive environments were twice as likely to meet physical activity guidelines as those in the least supportive neighbourhoods. The high prevalence of active transport (cycling) in the Netherlands likely contributes to the country's relatively low obesity."
The report also highlights that cultural body‐size preferences can have an effect on obesity rates. Increased food access and reduced physical activity may have a stronger influence in countries where large body size is associated with positive attributes – compared with countries where small body size is valued.
"In the United States, the percentage of overweight (but not obese) individuals who described their weight as “about right” increased significantly between the early 1990s and the early 2010s, suggesting changes in perceptions about healthy body size", the researchers suggest.
To read the full report, click here for A Cancer Journal for Clinicians publication
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