Breast Cancer Risk Factors

No one knows exactly what causes breast cancer; however, researchers have identified risk factors that make a woman more likely to develop the disease. They include:

• Age: The risk increases as a woman ages. Women over 60 are at the greatest risk. It is very uncommon for a woman to develop breast cancer before menopause.
• Personal history of breast cancer: A woman who has had breast cancer in one breast has an increased likelihood of developing the disease in her other breast.
• Family history: Breast cancer risk is higher among women whose close blood relatives have this disease. The relatives can be from either the mother's or father's side of the family.
• Certain breast changes: Having certain abnormal cells increases the chances of breast cancer.
• Genetic alterations: Changes in certain genes (BRCA1, BRCA2, and others) increase the risk of breast cancer.
• Reproductive and menstrual history: The older a woman is when she has her first child, the greater her chance of breast cancer. Women who began menstruation at an early age (before 12), went through menopause late (after 55), or never had children are at an increased risk.
• Race: Breast cancer occurs more frequently in Caucasian women than in Latina, Asian, or African American women.
• Radiation therapy to the chest: Women who had radiation therapy to the chest (including breasts) before age 30 have a greater chance of developing breast cancer.
• Breast density: Older women with mostly dense (not fatty) tissue on a mammogram are at increased risk for breast cancer.
• Taking DES (diethylstilbestrol): DES is a synthetic form of estrogen that was given to some pregnant women between 1940 and 1971.
• Being obese after menopause.
• Physical inactivity.