Breast cancer protective factors

We know from research that physical activity can help to prevent breast cancer. Studies have found a protective effect of about 30 to 40%. So being active may lower your risk by about a third. This is probably because physical activity lowers oestrogen and testosterone levels and can delay the start of periods.

Statistics show that if you breastfeed you are less at risk of developing breast cancer, particularly if you have your children when you are younger. The longer you breastfeed your baby, the more you lower your risk. We don't know exactly why this is. It may be because your ovaries don't produce eggs so often when you are breastfeeding. Or because breastfeeding changes the cells in the breast and may make them more resistant to the changes that lead to cancer.

A healthy diet may help prevent breast cancer. Look at the CancerHelp UK section about diet and preventing breast cancer for more information.

Research has shown that women regularly using aspirin or other non steroidal anti inflammatory medicines probably have a small reduction in their risk of breast cancer. Remember though that aspirin can irritate the lining of your stomach and cause bleeding. So you should talk to your own GP before starting to take it regularly. You shouldn't take it if you have any history of stomach ulcers.

Research is looking into drugs that may prevent breast cancer. 

Tamoxifen is a drug that has been used to treat breast cancer for more than 30 years. It works by stopping oestrogen from getting to hormone receptors on breast cancer cells. Oestrogen works on some types of breast cancer by triggering the cells to divide and multiply, so the cancer grows. Some women who are at high risk of breast cancer have been taking tamoxifen to see if it can stop them developing the disease. Trials have been carried out worldwide. Cancer Research UK have looked at the results of all these trials together. They show that tamoxifen can lower your risk of breast cancer if you are at high risk of the disease.

Tamoxifen seems to help to prevent breast cancers that have oestrogen receptors. It does not protect against oestrogen receptor negative cancers. There are also concerns about side effects in otherwise healthy women. The latest results from one of these trials, IBIS1, show that the benefits of tamoxifen in preventing breast cancer seem to last for at least another 5 years after the 5 years of tamoxifen treatment has ended. The trials show clearly that there is an increased risk of blood clots and of womb cancer for women taking tamoxifen. The risk of clots only lasted while women were taking tamoxifen. A small number of women were diagnosed with womb cancers after the treatment period, but these can be successfully treated. 

Other hormone drugs are being investigated for preventing breast cancer. Doctors hope that these other drugs may have fewer side effects than tamoxifen. These are raloxifene (Evista), exemestane (Aromasin), anastrozole (Arimidex) and tibilone (Livial). 

Raloxifene is a drug used to treat bone thinning (osteoporosis) in women who have had their menopause. Some doctors think it may help prevent breast cancer too and recent research has shown it may help to prevent breast cancer in post menopausal women.

An American systematic review in September 2009 found that tamoxifen, raloxifene and tibilone did reduce the risk of breast cancer but they also increase the risk of blood clots, womb cancer and strokes. We need more research to be certain about the benefits and risks of these drugs in preventing breast cancer. 

Anastrozole (Arimidex) is a drug that has mostly been used to treat secondary breast cancer. It is also licensed in the UK to treat early breast cancer. Anastrozole is being tested for preventing breast cancer in a trial called IBIS 2. 

You can find information about UK trials into preventing breast cancer on our clinical trials database. Choose 'breast' from the dropdown menu.

Coeliac disease is a disease of the small bowel. In people with coeliac disease, their body has an immune reaction to gluten, a protein found in rye, wheat and barley. This causes inflammation, which over time can damage the lining of the small bowel. This makes it difficult for the bowel to absorb the nutrients we need from our food. Symptoms of coeliac disease include bloating and discomfort in the tummy (abdomen), diarrhoea, low red blood cell count (anaemia) and tiredness. People with coeliac disease have to stick to a gluten free diet.

Some research suggests that people with coeliac disease have a lower risk of getting breast cancer. There is a study looking into why this might be the case. But there is also evidence that coeliac disease can slightly increase the risk of some other cancers, such as non Hodgkin's lymphoma.