Diet and physical activity in preventing cancer - Lung, Breast and Prostate cancer

The term cancer is used generically for more than 100 different diseases including malignant tumours of different sites (such as breast, cervix, prostate, stomach, colon/rectum, lung, mouth, leukaemia, sarcoma of bone, Hodgkin disease, and non-Hodgkin lymphoma). Common to all forms of the disease is the failure of the mechanisms that regulate normal cell growth, proliferation and cell death. Ultimately, there is progression of the resulting tumour from mild to severe abnormality, with invasion of neighbouring tissues and, eventually, spread to other areas of the body (1,2).

Global burden of cancer:

Cancer is a leading cause of death worldwide. The disease accounted for 7.6 million deaths (or around 13% of all deaths worldwide) in 2008. The main types of cancer leading to overall cancer mortality each year are:
• lung (1.37 million deaths)
• stomach (736 000 deaths)
• liver (695 000 deaths)
• colorectal (608 000 deaths)
• breast (458 000 deaths)
• cervical cancer (275 000 deaths)
More than 70% of all cancer deaths occurred in low- and middle-income countries. Deaths from cancer worldwide are projected to continue rising, with an estimated 13.1 million deaths in 2030 (3).

Risk factors contribute to the development of cancer:

A number of common risk factors have been linked to the development of cancer: an unhealthy lifestyle (including tobacco and alcohol use, inadequate diet, physical inactivity), and exposure to occupational (e.g. asbestos) or environmental carcinogens, (e.g. indoor air pollution), radiation (e.g. ultraviolet and ionizing radiation), and some infections (such as hepatitis B or human papilloma virus infection) (5).

Diagnosis: Diagnostic investigations including endoscopy, imaging, hystopathology, cytology, laboratory studies etc. (1).

Complications: Pain, depression, fatigue, sleep disorder and metastases are the major complications for cancer (1,2).

Lung cancer:

Lung cancer is the most common cancer in the world and was estimated to account for 1,239,000 cases and 1,103,000 deaths in 2000. (6) Three-quarters of all cases occur in men. The disease is most common in high-income countries and is increasing in some low-income countries such as China. It is almost always fatal, and is the chief cause of death from cancer: nearly 18 per cent of all deaths from cancer are from this type (7,8).

Risk factors:
• Heavy smoking increases the risk by around 30-fold, and smoking causes over 80% of lung cancers in Western countries (6).
• It has been estimated that the passive smoker increases his risk of lung cancer by at least 25% over the person not exposed. It is far more significant in most countries than other forms of air pollution (7).
• Arsenic in drinking water and (in smokers only) pharmacological doses of beta-carotene were found convincingly related to increase risk (8).
• There is limited evidence suggesting that, Low dietary intake of vitamin A, total fat, redmeat, saturated fat, pharmacological doses of retinol (smokers only), cholesterol, alcohol (6,8).
• Numerous observational studies have found that lung cancer patients generally report a lower intake of fruits, vegetables and related nutrients (such as b-carotene) than controls (6).

Dietary recommendation:• There is limited evidence suggesting that fruits and non-starchy vegetables, (6,8), Carotenoids, Vit-C, E, selenium and foods containing it, foods containing quercetin protect against lung cancer (8).

Recommendation for physical activity:• Physical activity may affect the duration of the potentially carcinogenic substances in contact with cells in the lungs, both by improving lung capacity and general blood supply, it is interesting to note that most of the published studies in this area shows that physical activity protect against lung cancer (9-11).

Breast cancer:

Breast cancer is the second most common cancer in the world and the most common cancer among women.Breast cancer was estimated to account for 1,105,000 cases and 373,000 deaths in women in 2000. Incidence rates are about five times higher in Western countries than in less developed countries and Japan (6).

Risk factors:
• High socio-economic status, early menarche, late first birth, late menopause, and a family history of breast cancer, rapid growth, greater adult height/weight gain, possibly total fat, saturated/animal fat, meat (12).
• Oestradiol and perhaps other hormones play a key role in the aetiology of breast cancer (4).
• Obesity increases breast cancer risk in postmenopausal women by around 50%, probably by increasing serum concentrations of free oestradiol. It was found convincingly related to increase risk (6).
• There is about 7% increase in risk for an average of one alcoholic drink every day (6).
• Alcohol interferes with oestrogen metabolism and action in multiple ways, influencing hormone levels and oestrogen receptors (8).

Dietary recommendation:
• Possibly fruits and vegetables, nonsolluble polysaccharides/fiber, carotenoids (12).
• Dietary fiber can play a role in preventing breast cancer through nonestrogen pathways among postmenopausal women (12).

Recommendation for physical activity:
• A number of studies and reports conclude that physical activity during work and leisure with an intensity that corresponds 6 METs (MET = metabolic equivalent, i.e. 6 METs corresponding light jogging for 4 hours per week) provides a reduction of breast cancer in postmenopausal women by 30-50 percent (13,14).• A study among women who are carriers of the hereditary genes (BRCA1 and BRCA2) have shown there is a earlier development of breast cancer among women who were physically inactive than those who were physically active and carriers of BRCA1 / BRCA2 (15).
• Another important aspect of physical activity as a protective factor for breast cancer is its special affet during the sensitive periods when breasts are particularly vulnerable of carcinogens, such as in puberty (2).

Prostate cancer:

Prostate cancer is the second most common cancer in men (and the sixth most common cancer overall) worldwide. Around 680 000 cases were recorded in 2002, accounting for around 12 per cent of all new cases of cancer in men (6 per cent overall). It is most commonly diagnosed in high-income countries, where screening is common (8).

Risk factors:
• There is limited evidence suggesting that processed meat/ red meat, and milk and dairy products (6,8,9) and foods containing calcium are a probable cause of this cancer (8).• Poissibly high levels of bioavailable androgens and of insulin-like growth factor-I (IGF-I).
• Diet might affect prostate cancer risk by affecting hormone levels, and recent data suggest that animal protein may increase levels of IGF-I (6).

Dietary recommendation:
• Foods containing lycopene, as well as selenium or foods containing it, food containing vit-E (6,8), pulses (legumes) including soya and soya products, alpha-tocopherol supplements probably protect against prostate cancer (8).
• It is unlikely that beta-carotene (whether from foods or supplements) has a substantial effect on the risk of this cancer (6,8).

Recommendation for physical activity:• A number of studies have examined the relationship between physical activity and prostate cancer. Most of these, especially when studying the most aggressive and advanced forms, has found that physical activity protects against prostate cancer (16,17).

References:

1. National cancer control programmes: policies and managerial guidelines. - 2nd ed. 2002. World Health Organization (WHO).
2. Thune I. Physical activity in the prevention and treatment of disease (FYSS). Cancer, chapter 19, 2011. p. 256-270.
3. Cancer.World Health Organization (WHO). Available at http://www.who.int/mediacentre/factsheets/fs297/en/
4. GLOBOCAN 2008. Available at http://globocan.iarc.fr/factsheets/populations/factsheet.asp?uno=900
5. Key TJ, Schatzkin A, Willett WC, Allen NE, Spencer EA, Travis RC. Diet, nutrition and the prevention of cancer, Public Health Nutr. 2004 Feb;7(1A):187-200.
6. The Facts World Health Organization Western Pacific Region- WHO. http://www.emro.who.int/tfi/SharedWorld-PassiveSmoking-LungCancer.htm
7. Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. Washington, (WCRF/AICR, 2007).
8. Gibney, M.J., (ED), Public Health Nutrition. Blackwell Publishing. 2007.
9. Thune I, Lund E. The influence of physical activity on lung cancer risk. A prospective study of 81,516 men and women. Int J Cancer 1997;70:57-62.
10. Steindorf K, Friedenreich C, Linseisen J, Rohrmann S, Rundle A, Veglia F, et al.Physical activity and lung cancer risk in the European Prospective Investigation into
Cancer and Nutrition Cohort. Int J Cancer 2006;119:2389-97.
11. Thorsen L, Skovlund E, Strømme SB, Hornslien K, Dahl AA, Fosså SD. Effectiveness of physical activity on cardiorespiratory fitness and health-related quality of life in young and middle-aged cancer patients shortly after chemotherapy. J Clin Oncol 2005;23:2378-88
12. Park et al. Dietary fiber intake and risk of breast cancer in postmenopausal women: the National Institutes of Health- Diet and Health Study, Am J Clin Nutr 90: 664-671, 2009.
13. Thune I, Brenn T, Lund E, Gaard M. Physical activity and risk of breast cancer. N Engl J Med 1997;336:1269-75.
14. Moradi T, Nyrén O, Zack M, Magnusson C, Persson I, Adami HO. Breast cancer risk and lifetime leisure-time and occupational physical activity (Sweden). Cancer Causes
Control 2000;11:523-31.
15.King MC, Marks JH, Mandell JB. Breast and ovarian cancer risk due to inherited mutations in BRCA1 and BRCA2. Science 2003;302(5645):643-6.
16. World Cancer Research Fund, American Institute for Cancer Research. Food, nutrition, physical activity, and the prevention of cancer. A global perspective. Washington
(DC): American Institute for Cancer Research (AICR); 2007
17. Friedenreich CM, Thune I. A review of physical activity and prostate cancer. Cancer Causes Control 2001;12:461-75.