PUBLIC HEALTH PAGES

World Cancer Research Fund, American Institute for Cancer Research. Second Expert Report, Food, Nutrition, Physical Activity and the Prevention of Cancer: A Global Perspective. United Kingdom: WCRF/AICR, 2001.

The report, "Food, Nutrition, Physical Activity and the Prevention of Cancer: A Global Perspective," is an icon of scientific publications that evaluate and systematize the existing evidence on the cause and effect relationship of food, nutrition and physical activity and their implications on the prevention of cancer. It has diverse components that are worth highlighting, primarily because they explicitly define specific recommendations to support the development of population policies for the prevention of cancer.

This report represents an exhaustive review of the epidemiological, clinical and experimental evidence that demonstrates the relationship between food, physical activity and the incidence and mortality of diverse types of cancer and other chronic diseases. It describes a very large strength of association for atherosclerosis, cardiovascular diseases and hypertension, and the evidence is highly suggestive for certain types of cancers, including esophageal, stomach, colon, breast, lung and prostrate cancers. The report also discusses the influence of alimentation on the predisposition to dental cavities, chronic hepatopathy, obesity and non-insulin-dependent diabetes mellitus, as well as on osteoporosis and the progression of chronic renal insufficiency.

Another important component included in this report is the association between environmental exposure and cancer. In general, we know that endogenous causes for cancer exist –those related to an individual's genetic heredity– as well as exogenous or external causes, such as environmental pollution, tobacco, diet and certain infections. Factors also exist related to lifestyle, such as obesity and physical activity.

While the etiology of cancer is multifactorial, and for many anatomical locations there is limited knowledge as to primary risk factors, epidemiological studies suggest that most cancers –between 65 and 70%– are produced by factors associated with lifestyle, particularly diet, body composition and physical activity, as well as with tobacco use and the excessive consumption of alcohol. In fact, as much as 30% of cancers appear to be directly related to nutrition and another 30% to tobacco. Therefore, quitting smoking and modifying eating patterns are key to the primary prevention of cancer.

While it is evident that nutritional factors are not the only cause of cancers that appear in different locations, nor are they the most responsible factors, extensive scientific evidence indicates that a more appropriate diet could reduce both the incidence and development of different types of cancers. Indeed, diet and nutrition appear to be implicated, to a greater or lesser extent, with the appearance and development of breast, colon, urinary bladder, prostate, esophagus, stomach, lung, uterine neck, endometrial, ovarian, gall bladder, liver and pancreas cancers.

The list is long enough, and some of the cancers represented here are so significant and frequent so as to warrant taking into account daily alimentation. Thus, dietary characteristics, composition and nutrients that are associated with diverse types of cancers are widely discussed in "Food, Nutrition, Physical Activity and the Prevention of Cancer: A Global Perspective." Discussed in great detail are the amount of calories in the diet, its fat content, vegetable fiber, alcohol, calcium, vitamins E and C, vitamin A and beta carotenes, folic acid and selenium, citric fruits and green-leaf and cruciferous vegetables.

This report has been developed thanks to a strategic alliance between the World Cancer Research Fund International and the American Institute for Cancer Research. It was compiled by 21 top-level researchers in the field worldwide, with the support of independent observers. Most significantly, members of this committee include, among others, committee chair Michael Marmot of the University College London, UK and Walter C. Willett of the Harvard School of Public Health, Boston, MA, USA, as well as leading researchers from countries on five continents. Also very important is the participation of two of the principal players in the nutrition study in Latin America, Dr. Juan Rivera of the Mexican National Institute of Public Health and Ricardo Uauy of the Institute of Nutrition and Food Technology, Santiago, Chile.

"Food, Nutrition, Physical Activity and the Prevention of Cancer: A Global Perspective" is part of a 27-year-long initiative, representing the most current and comprehensive analysis of the literature on diet, physical activity and cancer. It builds on the foundation first established by the WCRF global network in 1982 to analyze, interpret and publicize the available scientific evidence to help individuals reduce their risk of developing cancer. Thus, in 2001 the WCRF/AICR set itself a new objective to systematically review and assess the body of evidence on diet, physical activity and cancer and to publish a Second Expert Report. This report is the largest study of its kind and its conclusions are as definitive as the available evidence allows. The initiative has generously made the report available to consult directly at http://www.dietandcancerreport.org/.

The methodology for this Second Expert Report was based on 20 specially commissioned systematic literature reviews (SLRs). The methods specified in the manual were subject to a testing process for reproducibility. As a result, the manual was modified and it served as the basis for all the literature reviews of food, nutrition, physical activity and the risk of cancer for all relevant cancer sites, as well as of weight gain, overweight and obesity.

Among the principal contributions made by the Second Expert Report, "Food, Nutrition, Physical Activity, and the Prevention of Cancer: A Global Perspective" are its recommendations for public health policies for the prevention of cancer. These recommendations offer not only an individual perspective on the primary prevention of cancer but also have a large influence on public policies for each region.

The report features eight general and two special recommendations: 1) body fat - be as lean as possible, within the normal range of body weight, 2) physical activity as part of daily life, 3) limit consumption of foods and drinks that lead to weight gain, specifically limit energy-dense foods and avoid sugary drinks, 4) eat mostly foods of plant origin, 5) limit intake of red meat and avoid processed meat, 6) limit alcoholic drinks, 7) processing, preparation - limit consumption of salt and avoid mouldy cereals (grains) or pulses (legumes), 8) dietary supplements - aim to meet nutritional needs through diet alone, 9) breastfeeding (special recommendation) – mothers to breastfeed and children to be breastfed, and 10) cancer survivors (special recommendation) should follow the recommendations for cancer prevention

From its inception in the early 1980s, the WCRF global network has consistently been a pioneer and a leader in research and education on food, nutrition, physical activity and the prevention of cancer. The network has a special commitment to the creation of the most reliable science-based recommendations and their translation into information on which to base the actions of professionals, communities, families and individuals. The network includes the following organizations:

1. World Cancer Research Fund International (www.wcrf.org) is the association that co-ordinates the global network. The greatest impact can be achieved when allied organizations work together. Founded in 1999 and based in London and the US, WCRF International maximizes the potential of each member organization and strengthens their work. The development of the Second Expert Report is an example of all members of the global network coming together to achieve a common goal, in the interests of the network and all its members, and to further their joint mission.

2. Founded in 1982, the American Institute for Cancer Research (www.aicr.org) was the first organization to focus exclusively on the link between diet and cancer, and became the first member of the WCRF global network. Located in Washington, DC, AICR is now one of the largest cancer charities in the USA, funding scientific research and offering a wide range of education programs.

3. World Cancer Research Fund UK (www.wcrf-uk.org) became the second member of the global network when it was established in 1990. Based in London, it is the UK's leading charity in the field of diet, nutrition and cancer prevention and is responsible for raising awareness of the diet and cancer link among scientists, public health officials, media and the general public.

4. Wereld Kanker Onderzoek Fonds (WCRF NL) (www.wcrf.nl) began work in 1994 in the Netherlands as the third member of the global network. Based in Amsterdam, it is the only Dutch charity specializing in cancer prevention by means of food, nutrition, physical activity and associated factors, and has already made a major contribution to the acceptance of this message in the Netherlands.

5. World Cancer Research Fund Hong Kong (WCRF HK) (www.wcrf-hk.org) began work in 2002. As traditional Chinese diets have become more western, patterns of cancer incidence are changing. WCRF HK is playing a vital role, especially in working with government health departments in Hong Kong, to disseminate education and research programs on cancer prevention.

6. Fonds Mondial de Recherche contre le Cancer (WCRF FR) (www.fmrc.fr), founded in 2004, is the most recent member of the WCRF global network. Based in Paris, WCRF FR is developing its research and education programs, working with like-minded organizations to disseminate the vital information to help people make healthy choices and thus reduce their risk of cancer.

At the WCRF Global Network, our aim is not only to analyze and interpret the latest scientific findings in the field of diet, physical activity and cancer but also to share those findings with researchers, policy makers, health professionals and the general public. Thus, "Food, Nutrition, Physical Activity and Cancer: A Global Perspective," and its companion report, "Policy and Action for Cancer Prevention," are being communicated via launch conferences around the world, including a February 26th, 2009 launch of "Policy and Action for Cancer Prevention" at an international press conference at the Royal Society in London. Press activities also took place in the USA, Hong Kong, China, the Netherlands and France.

In summary, "Food, Nutrition, Physical Activity and the Prevention of Cancer: A Global Perspective" uses a systematic review to document and hierarchize the strength of association between diet and cancer and the recommendations that should invariably form part of population policies, programs and interventions for the prevention of chronic diseases and cancer. Because it provides scientific evidence for decision-making, this report should be widely disseminated in different fields, particularly academic, legislative and public policy.

Eduardo Lazcano-Ponce