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Understanding risk

A risk factor is any factor that is associated with an increased chance of developing a particular health condition, such as breast cancer. There are different types of risk factors, some of which can be modified and some which cannot.

Our risk of getting breast cancer means our chance of getting breast cancer. All women are at risk of getting breast cancer. As we get older, our risk increases.

Risk can be described in two different ways: relative risk and absolute risk.

Absolute risk refers to our chance of developing breast cancer during a given time. For example, the absolute risk of a woman developing breast cancer by the age of 85 years is 1 in 8. Absolute risk is of most value to women trying to determine how some risk factors might apply to them personally. However, most scientific or medical reports use relative risk.

Relative risk compares two absolute risks and emphasises the difference between the two, rather than the significance of the risk itself to an individual person.

For a particular risk factor for breast cancer, relative risk tells you how that risk for breast cancer compares with the risk of a woman who does not have that risk factor.

For example, drinking alcohol increases the risk of breast cancer. Women who have 1 standard drink per day have about a 7% greater risk of breast cancer than women who don’t drink. The absolute risk of developing breast cancer is still small in both groups, but the women who drink alcohol have a greater risk than those who don’t drink alcohol.

Having one or more risk factors does not mean that you will develop cancer. Many people have at least one risk factor but will never develop cancer, while others with cancer may have had no known risk factors. Even if a person with cancer has a risk factor, it is usually hard to know how much that risk factor contributed to the development of their disease.

Although some risk factors for breast cancer can’t be changed (for example, genetic factors), some can. Information about risk can help women make choices about lifestyle and other modifiable factors that affect risk for breast cancer.