One in nine women in Australia will develop breast cancer in their lifetime.
Generally it is not possible to determine what causes breast cancer in any individual woman. However, studies looking at very large numbers of women have shown there are some characteristics that are more common among groups of women who have developed breast cancer compared to groups of women who have not. These are called risk factors.
Having certain risk factors increases a woman's chance of developing breast cancer.
Some of the risk factors for breast cancer include growing older, having a strong family history of the disease, being overweight, drinking alcohol and other lifestyle and environmental factors. Some of these factors are beyond your control but there are some things you can change.
However, having one or more risk factors for breast cancer does not mean you will get breast cancer. And many women who develop breast cancer have no obvious risk factors.
On the other hand there have been some factors that are thought to have a protective effect against breast cancer, like having children at a younger age and breastfeeding. However, women with protective factors may still develop breast cancer.
A three-star rating system has been used to give you an indication of the level of breast cancer risk associated with the factors below. The greater the number of stars, the higher the risk.
Not all risk factors for breast cancer have been included in this resource. Factors not included are either not proven to be risk factors, or are of little consequence due to their rarity or to their small effect on risk, if any, based on current best evidence.