The World Health Organization’s (WHO’s) International Agency for Research on Cancer (IARC) last week published its World Cancer Report 2014, a collaborative effort providing “a professional, multidisciplinary assessment of all aspects of the geographical distribution, biology, etiology, prevention, and control of cancer.” In addition to a chapter on cancer etiology as it relates to diet, obesity and physical activity, the report’s third edition includes a section focusing on regulatory and legislative initiatives—such as the taxation of sugar-sweetened beverages (SSBs)—designed to minimize behavior-related carcinogenic risk. It also features a “Perspectives” article by Harvard School of Public Health Professor Epidemiology and Nutrition Walter Willett that reviews “our current state of knowledge on diet, nutrition, and cancer.”
Co-authored by Willett, the chapter on diet, obesity and physical activity warns that excess body fat “increases risk of cancers of the oesophagus, colon, pancreas, endometrium, and kidney, as well as post-menopausal breast cancer.” Singling out high meat consumption for its alleged association with colorectal cancer, this section ultimately recommends making the reduction of SSB consumption “a high priority” and argues that even though a diet high in fruits, vegetables and whole grains “does not appear to be as strongly protective against cancer as initially believed,”“this dietary pattern is still advisable because of the benefits for diabetes and cardiovascular diseases.” It also emphasizes the challenges of measuring diet in cancer epidemiological studies and new research describing the effect of diet on gut microbes.
Meanwhile, the section on legislative and regulatory initiatives addresses what it describes as “behavior-related” cancer exposures, including “tobacco smoking, alcohol consumption and excessive food intake.” Observing that regulatory measures to reduce obesity “are relevant to cancer control but adopted in the broad context of controlling diabetes and cardiovascular disease,” this chapter highlights a case study of Brazilian markets suggesting that SSB taxation “would be an effective way to control and reduce the consumption of these products.” As report editor Bernard Stewart, University of New South Wales, and IARC scientist Robert Baan note, however, “Measures to encourage good nutrition are available and are being further developed…, but these are not aimed at reducing exposure to agents generally recognized as carcinogens… A singular focus on cancer resulting from food contamina- tion underpinned historic United States legislation—the Delaney Clause [of the Food, Drug, and Cosmetic Act] mentioned above—but any such risk is now considered to be best addressed in the context of general food safety legislation.”
In his article titled “Diet, nutrition, and cancer: where next for public health?,” Willett also considers augmenting current legislative and regulatory initia- tives with public health approaches geared toward reducing obesity and encouraging physical activity. In particular, he discusses (i) education and awareness programs, specifically those that support “more intensive poli- cies, such as taxation”; (ii) food and menu labeling; (iii) economic strategies, including taxing SSBs and offering subsidies for whole grains, fruits and vegetables; (iv) limiting or promoting the availability of certain foods; (v) fortifying foods to prevent cancer, if evidence supports such measures; and (vi) banning specific foods or ingredients, or limiting serving sizes through regulation. “As discussed elsewhere in this Report, the process of research and translation leading to reductions in cancer rates has been highly successful for many types of exposures, including tobacco use, radiation, pharmaceuticals, and occupational hazards,” concludes Willett. “From this experience, we have learned much about the process of cancer prevention that can be applied to dietary factors.”