A risk factor is something that indicates a woman is more likely to develop breast cancer than average. They are not harmful in themselves. In fact, a woman's risk of developing breast cancer remains low even if she has several risk factors. About 85% of women who develop breast cancer do not have significant risk factors.
A history of breast cancer in immediate female relatives, especially at a young age, may indicate a genetic predisposition and constitutes a major risk factor in 5-10% of breast cancer patients.
Risk factors include:
- Gender and age - The two most significant risk factors are being a woman and getting older.
- Personal history of breast cancer or other cancer - The third most significant risk factor is having a personal history of breast cancer. A diagnosis of a typical ductal or lobular hyperplasia after biopsy may increase the risk of developing invasive breast cancer. Women who have been diagnosed with other cancers such as colon, ovarian or endometrial may be at an increased risk.
- Personal history of fibrocystic changes - Fibrocystic changes do not increase a woman's risk of developing breast cancer since almost all women have some aspect of this condition. Only breast duct lining changes showing atypia increase risk. This diagnosis can only be made through a biopsy.
- Family history - Not all families' histories of breast cancer increase the risk to unaffected family members. The risk increases when a first-degree relative (sister or mother) has developed breast cancer at an early age, particularly in their 30s before menopause, or where multiple family numbers have breast cancer. Both maternal and paternal sides of the family should be considered when looking at family history. Risk seems to increase when cancer has appeared in both breasts of relatives.
- Environment - Eighty-five to 90% of all breast cancers are diagnosed in women with no family history. Breast cancer is individual and based on the interaction between a woman's environment and heredity. American diets, which are high in animal products, contribute to an increase in breast cancer in contrast to vegetarian diets. No evidence exists, despite many scientific studies, of increased risk from exposure to herbicides, pesticides, hair dye, deodorants or other chemicals in our American lifestyle.
- Personal history of radiation - Radiation treatments in the vicinity of the breasts for treatment of childhood cancers increase risk greatly.