There are a number of “myths” about the risk factors and causes of breast cancer that sound plausible but have little or no scientific theory or data to support them.
There is no body of evidence that an increased risk for breast cancer can be attributed to:
- the use of antiperspirants,
- wearing a bra,
- a blow or injury to the breast,
- drinking milk,
- having silicon breast implants,
- having a mammogram.
Breast cancer myths - how are they generated?
The origin of most myths is not known, but the Internet and email has helped spread many of them. It is natural for people to look for an explanation that is easily understood about why they or a loved one has breast cancer. Many myths are attractive because they seem to offer a course of action that could help reduce the risk of breast cancer.
How to distinguish fact from fiction
It is not always easy to distinguish fact from fiction and myth from reality, especially if you are not an expert in science and medicine. It is important that people are not unduly worried or misled by information about breast cancer.
To ensure that you get the most accurate and up-to-date information on breast cancer, use authoritative and reputable sources such as:
- Talk to your doctor or another healthcare professional, such as the nurse at the local community health centre.
- Call The Cancer Council's Cancer Helpline - 13 11 20 from anywhere in Australia, operated by the state and territory Cancer Councils. For the price of a local call, you can talk with trained professionals who can answer your questions and send you additional information.
- Search this website for additional information and for links to other websites.
- Be skeptical of information that is not from recognised medical and scientific experts.
Some guidance for use of the Internet
There are thousands of Internet sites of variable quality and veracity. It is important to remember that anyone can put information on to the Internet with no requirements for scrutiny or accuracy.
Links to quality websites are available on this website and on the websites of state and territory cancer councils, government health and research agencies and recognised cancer support groups.
To ensure the credibility of information, check out who set up the site, when it was last updated, and that there are references to authoritative journals and institutions.
The use of antiperspirants
Is wearing deodorant linked to breast cancer?
There have been claims that using antiperspirant deodorant can cause breast cancer. This is based around a theory that antiperspirants cause toxins to build up in the lymph glands of the armpit, which then cause cancer in the breast tissue. Other people worry about chemicals contained in deodorants getting into the body through the skin and travelling to the breasts.
There is no quality evidence which shows the use of antiperspirant deodorants is associated with or causes breast cancer.
Wearing a bra
This explanation for the higher rates of breast cancer in developed countries was generated by Sydney Ross Singer and Soma Grismaijer, a husband and wife anthropology team, in their book "Dressed to Kill", published in 1995. They claim that tight-fitting bras constrict the lymph system, causing toxins to accumulate in the breasts and cause cancer.
This is not based on a credible hypothesis, for many of the reasons outlined in The use of antiperspirants and because lack of blood supply or increased pressure is not what causes normal cells to become cancerous. Although these researchers included some data from studies in their book to link bra wearing with breast cancer, these data have not been subject to peer review and have been criticised for lack of appropriate scientific controls.
There is a possible link between large breast size and an increased risk for breast cancer in post-menopausal women, but this is accounted for in part by the fact that obesity is a risk factor for breast cancer.
A blow or injury to the breast
A blow or injury to the breast does not cause breast cancer, but it can draw attention to a pre-existing lump. An injury can damage tissue and blood supplies, but does not damage the genetic material in the cells. It is errors in the replication of this genetic material that is the basis for the development of a cancer cell from a normal cell.
If you have breast pain as a result of a blow or otherwise, then consult your doctor.
Drinking milk
There have been a number of claims that the consumption of cows' milk can increase the risk for breast cancer. There are several issues to consider.
- There is some evidence that drinking milk with a high fat content may increase the risk of breast cancer, but this is thought to be due to the link between obesity and breast cancer as drinking skim milk seems to protect against cancer.
- Certain chemicals and pesticides, some of which have been shown to cause cancer, do show up as contaminants in both cows' milk and human milk. At this time there is no strong evidence to link these chemicals with increased risk for breast cancer, although this cannot be excluded. In Australia the levels of these contaminants in milk products is subject to testing and regulation.
- An argument is made that cows treated with bovine growth hormone (BST) have increased levels of a chemical called insulin-like growth factor (IGF-1) in their milk, and high blood levels of IGF-1 in humans have been linked with breast and prostate cancers. However it is not known if IGF-1 found in cows' milk can affect humans. More importantly, the use of BST is currently banned in Australia.
- Additional claims that oestrogen in cows' milk can affect women's breast tissue and cause cancer or that other, unspecified, milk compounds can cause oestrogen release in women have not been substantiated.
Silicon breast implants
Silicon breast implants are not linked to breast cancer risk. A large study on the long-term effects followed women with silicon breast implants for more than 10 years and showed no increased risk.
Some earlier studies of shorter duration actually showed exposure to implants reduced a woman's risk for breast cancer.
The guidelines for breast health and screening are also applicable to women with breast implants.
Mammograms
The known benefits of mammograms in the early detection of cancer far outweigh the very small potential risks of them causing cancer. The potential risk exists because exposure to ionising radiation can cause cancer. However given the limited number of mammograms a woman has in her lifetime, and the standards of the mammographic equipment in use today, the increased radiation exposure from a mammogram is no more than that from taking a plane flight across Australia .
Substantial exposure to X-rays, especially in childhood, is associated with an increased risk of cancer in later life. In the past, women who received treatment for scoliosis (curvature of the spine) in childhood and adolescence, have been shown to have an increased risk of dying of breast cancer. Today, more care is taken with these treatments and this is less likely to be the case.
