World Cancer Research Fund (WCRF/AICR)

This Euphocus provides an overview of the current state of evidence with regard to cancer prevention (or stimulation) by food, nutrition, overweight and physical activity. The results are mainly based on the extensive and authorative work carried out by the World Cancer Research Fund (WCRF), in collaboration with the American Institute for Cancer Research (AICR).

In 1997 the WCRF/AICR published its first report (WCRF/AICR, 1997). This report has had a great influence on cancer prevention at all levels. For instance, the methodology developed by WCRF/AICR to classify the strength of scientific evidence was later adopted by WHO in its 2003 report on 'Diet, Nutrition and the Prevention of Chronic Diseases' (WHO, 2003b).

Since the mid 1990’s there has been a dramatic increase in the amount of literature on this subject, in particular concerning the effects of overweight, obesity and physical activity. Also new methods for analyzing and assessing the evidence became available. An update of the first report was therefore needed, and this resulted last year in the publication of a second WCRF/AICR report (2007) entitled 'Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective'. In this new report, the main procedure and special features of the first report have been adapted and further developed. The results obtained in this second WCRF/AICR report served as the major source of information for this Euphocus.

Cancer and environmental factors

Cancer is a chronic disease that poses a major threat to mankind. It affects millions of people worldwide, and current trends, moreover, are unfavourable. Prevalence’s are increasing at a rate faster than the increase in global or EU population.

Cancer comprises over 100 different diseases, depending on the tissue affected. They are all characterized by uncontrolled cell growth due to specific genetic alterations (mutations) that in most cases are caused by the interplay between lifestyle and inborn (individual) genetic predispostion.The cancer pattern (distribution of different cancers) varies between countries/populations. Some cancer types are more common in lower income countries, while others are more common in higher income countries. Also, cancer patterns are found to change in time within countries/populations. For instance if countries become more urbanized and industrialized, or if populations migrate to other countries. Such changes indicate the important role of environmental factors as modifiers of cancer risk.

To date, known environmental factors that can modify cancer risk are: smoking (and other tobacco use); infectious agents; ionizing radiation (x-rays) and UV (A,B); industrial chemicals (and pollution); medication; food, nutrition, overweight (body fatness) and physical activity.

The role of food, nutrition, body fatness and physical activity, is among others supported by the fact that the changes in cancer patterns seem to coincide with the recent changes in patterns of food, drink, and physical activity. With industrialization and urbanization, food supply has become more secure and abundant. Diets contain more energy-dense foods (fats, oils) less vegetables and fruits, and often more alcoholic drinks. At the same time overall levels of physical activity have declined, and the lifestyle of people has become more sedentary. The strong increase in the number of people who are overweight or obese further serves to illustrate these trends.

Cancer, prevention, nutrition and physical activity

More conclusive evidence for the important role of food and nutrition (or specific food constituents), is derived from a broad range of in-depth studies during the past few decennia. These investigations included both epidemiological, intervention, experimental and mechanistic studies. However, not always did such studies yield clear-cut and consistent results. Consequently, conclusions about the strength of evidence for some food-cancer relations, have changed over time.

The combined scientific data concerning food, nutrition, overweight, and physical activity, (but also from other environmental factors), clearly suggest that cancer might be a preventable disease, at least to a certain degree. Thus, the most pressing challenge to date for scientists and health policy-makers is to invent, develop and launch measures that will effectively prevent cancer.

For nutrition this requires first of all, the establishment of clear and undisputed relations between certain nutritional factors and specific cancer types. In this Euphocus, an overview of such relations is presented, based on the recently published WCRF/AICR report (2007). In this report five different and descending categories are used to indicate the strength of evidence. The top two categories ‘convincing’ and ‘probable’ are considered to be the strongest. The categories refer to the likelihood of associations to be causal. According to WCRF/AICR both categories justify goals and recommendations designed to reduce cancer incidence. In this Euphocus attention will also be given to those public and personal recommendations in the report. Opportunities for intervention are discussed in the WCRF/AICR policy report, 2009. This policy report provides advice and guidance on lifestyle choices of people, that make it more likely to achieve the recommendations. It looks at how different levels of society can help ensure that those choices are easier for people around the world to make each day.

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