Cancer burden and causes in EU

Cancer is responsible for about 25% of all deaths in the EU, making it the second cause of death after cardiovascular diseases. There is a difference between the sexes, the number of male cancer deaths being somewhat higher than that of females.

In almost all EU countries the cancer pattern reflects that of the developed countries, with lung, colon/rectum, breast, prostate, stomach, pancreas, bladder and white blood cells as the most predominant sites. In terms of cancer deaths (both sexes combined), lung cancer and colorectal cancer are clearly number one and two. Lung cancer however, is more frequent in the new member states (East Europe, Baltic), while there is no clear gradient observed (north-south, or east west) for colorectal cancer. For the remaining cancer sites the exact ranking order shows some differences between the EU countries.

From the environmental factors, smoking (and other tobacco use) is still the most predominant one. In total it may be causally related to some 30% of all cancer cases and deaths. Regarding food and nutrition, it is now generally believed that dietary factors account for about 30 % of cancers in the EU as well. This is an overall estimate, which clearly varies for different cancer sites. Overweight and physical activity are estimated to account for between 20 and 33 % of cancers of the breast (postmenopausal), colon, kidney, endometrium and oesophagus.

Determinants of food, nutrition, overweight and physical activity

In this EUphocus specific and concrete definitions are used for food and nutrition which differ somewhat from the definitions used in the WCRF/AICR report (2007). Using these adapted definitions for food and nutrition, it becomes clear that nutrition (or diet), is the result of two major determinants, i.e. food supply and eating behaviour. These two determinants are in turn influenced by a range of other determinants. Changes in some of these subdeterminants, like those for food supply, seem to have coincided in the past with changes in cancer patterns.

Nutrition furthermore, involves two important aspects, i.e. quantity (energy intake) and quality (dietary composition). The quantity relates to the energy balance (energy intake minus expenditure). If positive, this may lead to weight gain, overweight and ultimately obesity. The latter two form a risk factor for several chronic diseases, including cancer.

The quality relates to the presence of nutrients (macro and micro), naturally occuring compounds/non-nutrients (a.o. fibre, secondary plant metabolites) and non-naturally occurring constituents like additives or contaminants. A rather complex relationship seems to exist between the different dietary constituents and some chronic diseases, including cancer.

Physical activity is the major determinant at the expenditure side of the energy balance. It can prevent weight gain at all ages, thereby decreasing the health risks of being overweight or obese. Also here, the two major determinants concern the supply side and the behavioural side, each with their own set of subdeterminants. Due to urbanisation and industrialisation, the overall levels of physical activity have declined over the past century, in particular (but not exclusively) in high-income countries.

Which factors increase or decrease cancer risk

The WCRF/AICR report (2007) distinguishes different grades of scientific evidence. Only the top two grades (convincing and probable), refering to the likelihood of a causal association, will be presented in this Euphocus.

Dietary composition

For 6 cancer sites there is convincing evidence of an increased cancer risk by the consumption of certain foods, drinks or food constituents. Four of these (mouth, oesophagus, colorectum, breast) concern alcoholic drinks. The other two (lung, liver) relate to specific carcinogenic contaminants in either drinking water or foods. Also beta-carotene supplements and red meat (or processed meat) convincingly increase the risk of respectively lung and colorectal cancer.

A probably increased cancer risk is found in four additional cancer sites (nasopharynx, stomach, prostate and skin) by the consumption of respectively salted fish, salted & salty foods, high calcium, and arsenic in drinking water

The available evidence for a protective effect against cancer by the consumption of certain foods, drinks and food constituents, is at best judged as ‘probable’. This judgement is made for 7 cancer sites. Four of these (mouth, lung, oesophagus, and stomach) concern the probable protective effects of non-starchy vegetables, fruits, foods with carotenoids and allium vegetables. The other three cancer sites (pancreas, colorectum, and prostate) concern mostly specific food constituents like folate, dietary fibre, garlic, calcium, lycopene or selenium.

Physical activity

Physical activity, besides being protective against weight gain, convincingly protects against colon cancer. It probably also protects against female hormone-related cancers like endometrium and breast cancer (postmenopause).

Overweight and obesity

There is convincing evidence that (excess) body fat increases the risk for six cancer sites (oesophagus, pancreas, colorectum, breast [postmenopause], endometrium, kidney). In addition, a probable increased risk exists for additional cancer types by body fatness (gall bladder), abdominal fatness (pancreas, breast [postmenopause], endometrium) and adult weight gain (postmenopausal breast cancer).

However, body fatness was also found to be probably protective against premenopausal breast cancer.

As a modifier of weight gain, physical activity convincingly decreases the risk of becoming overweight, while sedentary living increases it.

Growth and development

Greater adult attained height convincingly increases the risk of colorectum and breast cancer (post menopause). It probably also increases the risk for ovary and pancreas cancer. The risk of premenopause breast cancer is probably increased by both greater birthweight and greater adult attained height (see chapter 6, WCRF/AIRC 2007).

However, women who were breastfeeding their child were convincingly shown to have a reduced risk of breast cancer at all ages thereafter (both premenopause and postmenopause).

Latest insights and recommendations

The criteria for weighing the strength of the evidence in the WCRF/AICR report (2007), are more stringent than those used in their previous report (1997). As a result, some known relationships have been downgraded, like for instance the cancer protective effects of fruits and vegetables. But the upgrading of a few protective effects is also observed.

In addition, the total evidence for increased cancer risks by overweight and obesity has become much stronger. Also some some new cancer risks (skin, pancreas, ovary), or new protective effects (colorectum, prostate, endometrium breast) were noted for certain foods or food constituents.

Finally, the review of all available data and the conclusions by WCRF/AICR have also led to a comprehensive set of 10 recommendations. Moreover, the eight general and two special recommendations have also been translated into public health goals for populations (to assist health professionals) and into personal recommendations to guide people (individuals, families or communities).