One in Nine
The VVF asks why breast cancer cases are
rising and investigates the role of diet
THE CAUSES OF BREAST CANCER
The risk of developing breast cancer is very small in young women and increases as women get older; more than half of breast cancers occur in women over the age of 65 (Cancerbackup, 2007). Some factors may slightly increase a woman’s risk of developing the disease, these are listed below:
- Having had breast cancer
- Having benign (non-cancerous) breast disease
- Genetics – breast cancer in the family (see below)
- Early puberty/menstruation – before the age of 11
- Late menopause – after age 54
- Having a first child late in life
- Having no or few children
- Not breast-feeding long term
- Exposure to radiation
- High dietary fat intake
- Overweight and obesity – particularly for postmenopausal women
- Moderate to heavy consumption of alcohol
- Oral contraceptives (the pill) and hormone replacement therapy (HRT) may very slightly increase the risk of breast cancer
In addition to the above, studies have included a small number of chemicals identified as mammary carcinogens or hormone disruptors which may have implications for breast cancer. However, evidence is emerging for associations between breast cancer and polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and organic solvents (Brody et al., 2007). PCBs are persistent organic pollutants that do not degrade easily and so are widespread in the environment. They are generally present at low concentrations in most foods, especially fat-containing foods such as milk and meat (FSA, 2000). PAHs are ubiquitous in air pollutants produced from vehicle exhausts (Brody et al., 2007). Organic solvents are commonly used in detergents (citrus terpenes), dry cleaning (tetrachloroethylene), paint thinners (toluene and turpentine), nail polish removers and glue solvents (acetone, methyl acetate, ethyl acetate) and in perfumes (ethanol).
Just how much some of these factors contribute to the risk of breast cancer is difficult to say. However, the aim of this report is to investigate the somewhat overlooked role of dietary factors. That said, the role of genetics in breast cancer deserves further discussion.
The genetic link
Much has been made of the link between genes and breast cancer. The genes BRCA1 and BRCA2 have received the most attention since they were first discovered in 1994 and 1995 respectively. A fault in either of these two genes can increase the chances of getting breast cancer. However, even among women with high-risk BRCA1 and BRCA2 gene mutations, evidence suggests that non-genetic (environmental) factors influence risk. A substantial review of the research, published in the journal Cancer,reported that more women born after 1940, carrying a fault in either, or both of these genes, were diagnosed with breast cancer by the age of 50 than those born before 1940 (Brody et al., 2007). In other words, the women born after 1940 were exposed to some environmental factor that increased their risk of developing breast cancer.
There are two other very rare genes which are thought to account for less than two per cent of all breast cancers: the P53 gene and the AT (ataxia telangiectasia) gene (Cancerbackup, 2006).
It is important to remember that having an abnormal gene does not mean that a person will definitely develop breast cancer, but does mean they are considerably more at risk of developing the condition than someone who does not have one of the abnormal genes. Interestingly, with a faulty gene, the probability of developing cancer has increased over the last 30 or more years from about 40 per cent to about 70 per cent, probably due to environmental and lifestyle factors (CANCERactive, 2007). In other words you can cut your risks, even if you have a faulty gene, by making changes to your diet and lifestyle.
The discovery of genes linked to breast cancer has given rise to a certain degree of ‘genetic fatalism’, encouraging some to think that their chances of getting breast cancer are entirely down to fate. However, scientists estimate that only around five to 10 per cent of breast cancers are due to inheriting abnormal genes (Cancerbackup, 2007). This means that the vast majority of cancers (90 per cent) are not caused by abnormal genes. Secondly, it is important to remember that having an abnormal gene does not mean that a person will definitely develop breast cancer, but does mean they are more at risk of developing the condition than someone who does not have one of the abnormal genes.
By: Dr Justine Butler, Senior Health Campaigner, Vegetarian & Vegan Foundation (VVF)
Published by: Vegetarian & Vegan Foundation, Top Suite, 8 York Court, Wilder Street, Bristol BS2 8QH
T: 0117 970 5190
E: info@vegetarian.org.uk
W: www.vegetarian.org.uk
© Vegetarian & Vegan Foundation 2007
Registered charity 1037486
Illustration: Philip Downs
Graphic design: The Ethical Graphic Design Company Ltd
Also by Dr Justine Butler: White Lies: the Health Consequences of Consuming Cow’s Milk available from: www.vegetarian.org.uk/campaigns/whitelies/resources.html and A Fighting Chance: a Guide to Healthy Eating to Help Prevent and Overcome Breast Cancer available from: www.vegetarian.org.uk/campaigns/breastcancer
Recommended reading: Your Life in Your Hands by Professor Jane Plant available from: www.vegetarian.org.uk/shop/bookshealth.shtml
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