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Cancer prevention: simple lifestyle advice for patients

Silvia Pastorino
MSc BSc(Hons) APHNutr
Health Professionals Publications Manager
WCRF UK

A recent survey by World Cancer Research Fund found that a large propoprtion of health professionals, including nurses, were not aware of how lifestyle affects cancer risk. Silvia Pastorino looks at the important role nurses can play in helping to prevent cancer

According to a recent World Cancer Research Fund (WCRF) UK survey, only 64% of health professionals are aware that lack of physical activity increases the risk of cancer, while 36% believe drinking coffee can cause cancer, despite no strong evidence of a link between coffee and the disease.1 Interestingly, a previous survey commissioned by WCRF UK found that only 12% of the general public thought coffee was a cause of cancer. However, a much higher percentage of health professionals knew that poor diet, being overweight and alcohol increased cancer risk, compared to the general public.

The survey of 143 practice nurses, health visitors and GPs was small but it suggested that some health professionals are still not aware of the lifestyle factors that can increase cancer risk.
A previous study published in Public Health Nutrition found similar cancer awareness levels among health professionals: only 76% of practice nurses thought there were clearly established links between diet and cancer.2

A reason for these findings might be the relatively limited nutritional training nurses and other medical professionals receive. The WCRF 2009 Policy Report, Policy and Action for Cancer Prevention, advocated that nutrition and public health, including cancer prevention, should be prioritised in core training, practice and professional development for health workers.3

It is crucial that healthcare professionals are up-to-date with the latest scientific evidence on cancer prevention. Nurses, in particular, are well placed to promote the message that cancer is a highly preventable disease.

What does the scientific evidence show?
In 2007, WCRF published a landmark expert report, Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective, the most comprehensive ever published on the subject.4 It is based on an in-depth analysis of more than 7,000 scientific studies published on cancer prevention over the last 50 years.

A panel of 21 world-renowned scientists reviewed and judged the research evidence and developed 10 recommendations for cancer prevention that people can incorporate into their daily lives. To keep the evidence current, WCRF is now working on a Continuous Update Project with Imperial College London to update the evidence on an ongoing basis.

The 2007 report found that food, nutrition and physical activity are important determinants of cancer risk. Experts estimate that around a third of the most common cancers in the UK could be prevented by eating a healthy diet, being physically active and maintaining a healthy weight. This equates to about 80,000 cases of cancer each year, demonstrating how high the stakes are and why it is important to help people make informed choices.

WCRF UK Recommendations for Cancer Prevention
1: Be as lean as possible without becoming underweight
Excess body fat increases the risk of a number of cancers, including bowel, breast (postmenopausal), endometrium, oesophagus, kidney and pancreas.

There are several mechanisms through which excess body and abdominal fat could influence cancer risk, such as raising the inflammatory response, increasing levels of circulating oestrogens and decreasing insulin sensitivity, all of which can promote cancer growth.

2: Be physically active for at least 30 minutes every day
Moderate physical activity protects against cancers, including bowel and breast cancer. Physical activity helps maintain a healthy weight. It also helps reduce levels of circulating oestrogens and androgens, which may explain the protective effect for breast cancer. In relation to bowel cancer, physical activity may bring about a reduction in insulin resistance, have an effect on endogenous steroid hormone metabolism and promote reduced gut transit time.

3: Avoid sugary drinks. Limit consumption of energy-dense foods (particularly processed foods high in added sugar, or low in fibre, or high in fat)
Sugary drinks such as colas and fruit squashes are probably causes of weight gain. Fruit juices, even
without added sugar, are likely to have a similar effect, so advise patients not to drink them in large
quantities.

Energy-dense foods are high in fats and/or sugars and can be low in nutrients. Foods that have more than about 225-75 kcal per 100 g are considered to be energy dense. These foods increase the risk of obesity, and therefore could also be expected to indirectly increase the risk of those cancers that are linked to obesity.

Water is the best choice in place of sugary drinks - unsweetened tea and coffee are other alternatives. Encourage patients to base meals on lower energy-dense foods such as vegetables, wholegrains and fruits.

4: Eat more of a variety of vegetables, fruits, wholegrains, and pulses such as beans
Vegetables, fruits and other foods containing dietary fibre (such as wholegrains and pulses) probably protect against a range of cancers, including mouth, stomach and bowel cancer, and help to protect against weight gain and obesity.
Plant foods also contain a wide variety of micronutrients and other bioactive compounds that may affect cancer risk. For example, phytochemicals can act as antioxidants, preventing damage to cells and DNA.

Encourage patients to eat at least five a day and to include relatively unprocessed cereals (eg, brown rice, wholegrain bread and pasta) and/or pulses at
every meal.

5: Limit consumption of red meat (such as beef, pork and lamb) and avoid processed meat
Red meat, particularly processed meat, is a cause of bowel cancer. Red meat contains haem, which can promote the formation of carcinogenic N-nitroso compounds. Nitrites, which are used to preserve processed meat, can also promote the formation of N-nitroso compounds.

Weekly intake of red meat should be less than 500 g (cooked weight) or about 700-750 g raw weight. Advise patients to avoid processed meats such as bacon, ham and some sausages.

6: If consumed at all, limit alcoholic drinks to two for men and one for women a day
All types of alcohol are a cause of a number of cancers, including bowel and breast cancer. There are several possible mechanisms to explain this. Alcohol breakdown of products in the body may be carcinogenic. Heavy consumers of alcohol may also have diets deficient in essential nutrients, making tissue susceptible to carcinogenesis. 

Evidence shows that any alcohol consumption can increase risk of cancer. Small amounts of alcohol may have a protective effect on the heart - but the benefits only outweigh the risks in those particularly at risk of heart disease, such as men aged over 40 and postmenopausal women. Advise patients that if they choose to drink they should do so in moderation.

7: Limit consumption of salty foods and foods processed with salt (sodium)
Salt and salt-preserved foods are probably a cause of stomach cancer. Evidence from laboratory experiments shows that a high salt intake damages the lining of the stomach. It may also increase endogenous N-nitroso compound formation, which is linked to cancer.

Our daily salt intake should be less than 6 g. Encourage patients to use herbs and spices to flavour food and remember that processed foods, including bread and breakfast cereals, can contain large amounts of salt.

8: Don't use supplements to protect against cancer
There is limited evidence about the risks and benefits of supplements when taken in physiological doses in the general population, as it is difficult to establish their effects on health with confidence. While some micronutrients might be safe or even beneficial at low doses, they can become harmful at higher intake levels, especially in some at-risk groups. For example, high doses of beta-carotene in supplements increase lung cancer risk among smokers.

It is best to advise patients to choose a balanced diet rather than take supplements. However, supplements are advisable for general health for certain groups of people, such as pregnant women and the elderly.

Special populations
9: It is best for mothers to breastfeed exclusively
for up to six months and then add other liquids
and foods

Breastfeeding protects mothers against breast cancer and babies from excess weight gain throughout life. Breastfeeding may protect against breast cancer because of altered hormone levels, particularly androgens, during breastfeeding.

10: After treatment, cancer survivors should follow
the Recommendations for Cancer Prevention
Maintaining a healthy weight through diet and physical activity may help to prevent cancer recurrence.

Encourage cancer survivors to seek nutritional advice from an appropriately qualified healthcare professional.

No set of recommendations designed to prevent cancer would be complete without discouraging the use of tobacco. Always encourage patients not to smoke or to try to give up if they do.

How to keep up-to-date
World Cancer Research Fund has a range of health education publications and material that translate the science into practical and positive advice for patients. These can be downloaded for free or ordered from
our website.

We also publish Informed, a quarterly newsletter aimed at health professionals, as well as an e-newsletter. You can sign up for both of these for free at the health professionals' section of our website at:
www.wcrf-uk.org/health-professionals

References
1. World Cancer Research Fund (WCRF). Health professionals "less aware than public" on myth that coffee increases risk of cancer. Available from: www.wcrf-uk.org/audience/media/press_release.php?recid=88
2. Hankey CR, Eley S, Leslie WS, Hunter CM, Lean MEJ. Eating habits, beliefs, attitudes and knowledge among health professionals regarding the links between obesity, nutrition and health. Public Health Nutr 2004;7(2):337-43.
3. World Cancer Research Fund (WCRF)/ Association for International Cancer Research (AICR). Policy and Action for Cancer Prevention. Food, Nutrition, and Physical Activity: a Global Perspective. Washington DC: AICR, 2009.
4. World Cancer Research Fund (WCRF)/ Association for International Cancer Research (AICR). Food, Nutrition, Physical Activity, and  Prevention of Cancer: a Global Perspective. Washington DC: AICR, 2007.