CancerQuest >> Cancer by Type >> Breast Cancer

Breast Cancer: Risk Factors I

Factors that influence risk of developing breast cancer include:

• Prior History of Breast Disease
• Family History of Breast Disease
• Age
• Race
• Reproductive and Menstrual History
• Radiation Exposure
• Dietary Factors

The relative effects of these and other risk factors in any given case of cancer is variable and very difficult to determine with accuracy at this time. Some of these and other risk factors are discussed on the following pages.

Prior History of Breast Disease

History of breast cancer, regardless of the type, greatly increases an individual's risk for future development of breast cancer. The second occurrence is most likely to be classified as invasive and ductal, rather than a lobular breast cancer. Such women are strongly advised to carefully monitor themselves and receive mammograms on a regular basis.

Family History of Breast Disease

It is possible to inherit defective genes that lead to the development of a familial form of a particular cancer type. Individuals with a family history of breast cancer are therefore at an increased risk of developing the disease. The degree of risk depends upon the type of relative affected. For example, risk is higher if an immediate family member has been diagnosed with breast cancer. The more closely related an individual is to someone with breast cancer, the more likely they will share the same genes that increased the risk of the affected individual. Risk also increases with the number of relatives affected.

Age

Breast cancer risk is low before age 30 and increases with age, leveling off at the age of 80. More information about the relationship between cancer and age can be found in the Cancer Biology chapter of this site.