A risk factor is any factor that is associated with an increased chance of developing a certain condition, such as breast cancer. There are different types of risk factors, some of which can be changed or modified, and some which cannot.
Risk factors for breast cancer can include personal factors, family history and genetic factors, reproductive, lifestyle and environmental factors and medical history and medications.
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.