Preventability Estimates

Preventability estimates are required so that policy-makers can assess the impact of different approaches to reduce cancer risk. It is important to identify how many cases of cancer could be prevented by changes to the foods we eat and the amount of physical activity we do.

The original estimates on the preventability of cancer and the methods used to calculate them were published in The Policy Report. These estimates are based on the 10 Recommendations for cancer prevention featured in the Second Expert Report.

These original estimates have now been updated with new data from:

• GLOBOCAN 2008 on cancer rates(1)
• Continuous Update Project for cancers of the breast, colorectum and pancreas(2)

In order to estimate how preventable cancer is in different parts of the world figures were calculated for two high-income countries (USA and UK), a middle-income country (Brazil) and a low-income country (China).

(1) Ferlay J, Shin HR, Bray F, Forman D, Mathers C and Parkin DM. GLOBOCAN 2008, Cancer Incidence and Mortality Worldwide: IARC CancerBase No. 10 [Internet]. Lyon, France: International Agency for Research on Cancer; 2010. Available from: http://globocan.iarc.fr

(2) Details provided in footnotes to tables on food, nutrition, body fatness and physical activity; and body fatness

Methods

Preventability estimates were calculated using information on:

• Cancer risk associated with lifestyle factor
• Prevalence of low, moderate and high levels/consumption of lifestyle factor in each country
• Incidence of different cancers in each country

The methods used to calculate the estimates as well as more information and further estimates can be found in Appendix A of the Policy Report.

However, in brief the estimates were made for lifestyle factors judged to be convincing or probable modifiers of cancer risk in the Second Expert Report or Continuous Update Project, with a few exceptions; thus 12 cancers were included.

Highest versus lowest risk estimates were used for cancer risk. One research study (ideally large and recent) was chosen from those collected as part of the Second Expert Report or Continuous Update Project, where the size of effect was representative of all studies.

Information on prevalence of lifestyle factors was obtained from national surveys. These two pieces of information were used to estimate preventability for each lifestyle factor.

The information on incidence of cancer was used to provide an overall estimate of preventability for each country.

Cancer preventability was estimated for the combination of risk factors related to food, nutrition, body fatness and physical activity and also separately for body fatness.