For those cancers in which risk is associated with high body mass index, North America has the highest percentage of cancer incidence attributable to obesity, according to a population-based study in the Lancet Oncology.

The investigators considered “only cancers reported by the World Cancer Research Fund as having sufficient evidence to be associated with high BMI”: colon, rectum, pancreas, kidney, esophageal adenocarcinoma, postmenopausal breast, endometrial, ovary, and gallbladder (women only) (Lancet Oncol. 2014 Nov. 26 [doi:10.1016/S1470-2045(14)71123-4]).

The study took into account the time lag between the exposure (high BMI) and outcomes (cancer incidence) by estimating the global population attributable fraction (PAF) of cancer incidence in 2012 attributable to high BMI in 2002. The investigators calculated PAFs using a formula and approach suggested by the Comparative Risk Assessment Collaborative Group.

Of all new cancer cases diagnosed worldwide in 2012, 3.6% or 481,000 of the cases were attributable to obesity, reported Melina Arnold, Ph.D., of the International Agency for Research on Cancer, Lyon, France, and her associates. In North America, 20.8% of high-BMI cancers in men and 19.2% in women were attributable to obesity, Dr. Arnold and her associates estimated. The next-highest of the 12 regions in the study were Northern Europe for men (18.3%) and Eastern Europe and the Middle East/North Africa for women (both 18.2%),

The regions with the lowest estimated rates were Southeast Asia and South-central Asia for both men (3.6% and 3.7%, respectively) and women (6.2% and 5.4%, respectively), according to calculations based on data from the World Health Organization’s GLOBOCAN project and several other sources.

The investigators said that they had no conflicts of interest. The study was funded by the World Cancer Research Fund International.