Global Cancer Burden Attributable to High BMI Revealed

Approximately half a million new cases of cancer in 2012 could be associated with obesity

medwireNews: A worldwide population-based study estimates that approximately 4% of all new cancers in 2012 can be ascribed to a high body mass index (BMI).

Melina Arnold, from the International Agency for Research on Cancer in Lyon, France, and co-workers say that this figure equates to an estimated 481,000 of total cancers in adults aged 30 years and older.

When only cancers known to be associated with a high BMI, such as oesophageal adenocarcinoma, colon, rectal and postmenopausal breast cancer, were considered, 12.8% of those in 2012 could be attributed to obesity.

The team arrived at these population attributable fractions (PAFs) by combining relative risk estimates from meta-analyses of BMI and cancer incidence with global cancer incidence data from GLOBOCAN 2012 and BMI estimates stratified by country, gender and age group in 2002, assuming a 10-year lag between high BMI and cancer occurrence.

The incidence of new cancers attributable to high BMI varied by gender, with a higher occurrence in women than in men, at 5.4% and 1.9%, respectively, mainly owing to endometrial and postmenopausal breast cancers.

“Particularly, in regions with a fairly low incidence of high-BMI-related cancers, such as Asia and sub-Saharan Africa, the proportion of new cancer cases attributable to high BMI was two to three times greater for women than for men”, write the investigators in The Lancet Oncology.

Stratification by the human development index (HDI) showed that a larger proportion of total cancers could be attributed to obesity in countries with a very high HDI compared with those with a low HDI, at 7.8% versus 1.5% in women and 3.2% versus 0.3% in men.

Additionally, the researchers found that an estimated 118,000 cases of obesity-related cancer in 2012 could potentially have been averted if the mean population BMIs had remained unchanged from those recorded in 1982.

They conclude: “Assuming a causal link between high BMI and cancer incidence, if the current pattern of population weight gain continues, it will lead to further increases [in] future burden of cancer, especially in regions such as Latin America and the Caribbean and north Africa, where the largest increases in the prevalence of obesity have occurred in the past three decades.”

In an accompanying comment, Benjamin Cairns, from the University of Oxford, UK, points out that although nearly half a million new cases of cancer associated with high BMI is a large number, “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”, he cautions.

References

Arnold M, Pandeya N, Byrnes G, et al. Global burden of cancer attributable to high body-mass index in 2012: a population-based study. Lancet Oncol 2014; Early online publication 26 November. doi:10.1016/S1470-2045(14)71123-4

Cairns BJ. Cancer and high body-mass index: global burden, global effort? Lancet Oncol 2014; Early online publication 26 November. doi:10.1016/S1470-2045(14)70373-0

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