Researchers are estimating that worldwide, about 3.6% of new cancer cases in 2012 in adults aged 30 years or older may be attributed to a high body mass index (BMI; defined as 25 kg/m2 or greater), equating to about 481,000 new cancer cases.
The risk for these cancers was higher in women (5.4%) than in men (1.9%), with corpus uteri, postmenopausal breast, and colon cancer accounting for 72.5% of the total attributable cases in women. In addition, the study showed that the burden was higher in more developed countries, with 64% of BMI-related cancers occurring in North America and Europe.
These data and more were published recently in Lancet Oncology, by Melina Arnold, PhD, of the International Agency for Research on Cancer, Lyon, France, and colleagues.
“Based on our results, historical and continuing increases in the global prevalence of high BMI, especially in younger cohorts, are expected to translate into further increases in cancer burden in the future,” Arnold and colleagues wrote. “Our results should inform health policy in terms of targets for prevention programs, while emphasizing existing gaps in our knowledge about the association between BMI and cancer.”
Using data from a number of sources including the GLOBOCAN database of cancer incidence and mortality for 184 countries, Arnold and colleagues created a model to estimate the fraction of cancers associated with excess bodyweight in countries and regions worldwide in 2012, and the proportion that could be attributed to increasing BMI since 1982.
While the data showed that postmenopausal breast, corpus uteri, and colon cancers were responsible for the majority of BMI-related cancers in women (almost 250,000 cases), data showed that in men colon and kidney cancers accounted for 66% of all BMI-related cancers.
Arnold and colleagues also found that in developed countries 8% of cancers in women and 3% in men were linked with high BMI. In comparison, in developing countries, only 1.5% of cancer in women and 0.3% of cancers in men were linked to BMI.
In an editorial that accompanied the research, Benjamin Cairns, PhD, from the University of Oxford, pointed out that there is research clearly supporting that BMI has a causal association with the risk of breast and endometrial cancers via hormonal pathways, making the risk modifiable.
“This possibility is especially encouraging because these cancers also represent a substantial proportion of all adult cancers associated with high BMI,” Cairns wrote.
However, overall Cairns implied that these results need to be put into perspective, “If 3.6% of all cancers are associated with high BMI, that is nearly half a million cancers, but this number is large mainly because the world population is large. Global health resources specifically for cancer prevention are not so large, and the resources targeted at obesity must be balanced against those for other important causes of cancer, particularly infections and tobacco use, which are each associated with much larger proportions of cases.”