Researchers from the International Agency for Research on Cancer (Lyon, France), estimate that a quarter of obesity-related cancers diagnosed in 2012 were related to the rising body mass index (BMI) observed in the general population since 1982.
The team, led by Melina Arnold of the International Agency for Research on Cancer, say that these 118,000 cases were “realistically avoidable”.
To arrive at this conclusion, the team assimilated data from a variety of sources, including the GLOBOCAN database of cancer incidence and mortality for 184 countries. A model was then created to estimate the fraction of cancers associated with excess bodyweight worldwide in 2012 and the proportion of these cases that were due to increasing BMI.
The results indicate that obesity-related cancer is more problematic in women than men. The data revealed that excess weight in women caused 5.4% or 345,000 new cases. Approximately 250,000 of these cases were postmenopausal breast, endometrial and colon cancers. In men, this figure was 1.9% or 136,000 cases. Colon and kidney cancers accounted for over two-thirds of all obesity-related cancers in men, or almost 90,000 cases.
In developed countries, 8% of cancers in women and 3% in men were attributable to excess weight. There was great disparity when this was compared with developing countries, where 1.5% of female cases and 0.3% of male cases were attributable to excess weight.
Geographically, North America contributed 111,000 new obesity-related cancers in 2012. This equates to 23% of new obesity-related cancers worldwide. Sub-Saharan Africa, on the other hand, contributed only 1.5% of the worldwide total. Within Europe, there was highest disease burden in Eastern Europe, where 66,000 cancers were caused by excess BMI.
Obesity-related cancer cases fluctuated greatly between countries. In men, the Czech Republic saw particularly high rates of obesity-related cancer, with it causing 5.5% of the nation’s total cases. Other nations with high rates in males were Jordan and Argentina (4.5%), and the UK and Malta (4.4%). In women, Barbados had a rate of 12.7%, followed by the Czech Republic (12%) and Puerto Rico (11.6 %). Countries in sub-Saharan Africa had the lowest rates of obesity-related cancer, with less than 2% in men and below 4% in women.
“Our findings add support for a global effort to address the rising trends in obesity. The global prevalence of obesity in adults has doubled since 1980. If this trend continues it will certainly increase the future burden of cancer, particularly in South America and North Africa, where the largest increases in the rate of obesity have been seen over the last 30 years,” explained Arnold.
Commenting on the findings, Benjamin Cairns from the University of Oxford (UK) said: “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.”