The exact causes of breast cancer have not yet been determined. The likelihood of developing breast cancer has been linked to a number of risk factors. Some risk factors are independent of our actions, while others can be acted upon.

Independent factors include:

• aging
• being white
• heredity (mutations altering genes)
• menstruating at an early age or having menopause later on
• personal history of breast cancer or other breast disease
• breast tissue that is dense on a mammogram

Dependant risk factors include:

• older age at first birth or never having given birth
• not having breastfed
• treatment with radiation therapy to the breast/chest or radiation exposure
• taking hormones such as estrogen and progesterone
• being overweight
• alcohol or tobacco consumption
• low physical activity

Hereditary breast cancer makes up 5% to 10% of all breast cancers. Women carrying mutations in either the BRCA1 or BRCA2 genes have an increased risk of breast and ovarian cancer. It is estimated that women with mutations in the BRCA1 or BRCA2 gene have a 50% to 85% risk of developing breast cancer. Men who have the modified gene also have an increased risk of developing breast cancer.

Thanks to research, tests, which can detect these modified genes,  have been developed. These genetic tests are often performed for members of families with a high risk of cancer.

References