- Gender - being a woman is the main risk factor for breast cancer.
- Increasing age - as women get older their risk of developing breast cancer increases.
- Breast cancer genes - about 5% to 10% of breast cancers are believed to be inherited.
- Family history of breast cancer - having a mother, sister, or daughter with breast cancer about doubles a woman's risk. (It's important to note that 70% to 80% of women who get breast cancer do not have a family history of this disease).
- Personal history of breast cancer - a woman who has had cancer in one breast is more likely to develop it in the other breast or in remaining breast tissue.
- Race- White women are slightly more likely to get breast cancer than are African-American women. But African-American women are more likely to die of this cancer. At least part of the reason seems to be because African-American women have faster growing tumors. Asian, Hispanic, and American Indian women have a lower risk of getting breast cancer.
- History of benign breast disease - women who have a history of certain types of non-cancerous tumors and cysts in their breasts are more likely to develop breast cancer.
- Woman who start their periods (menstruation) at a young age, start menopause at a late age, have their first child later in life, and have no full-term pregnancies may have an increased risk of developing breast cancer.
- Studies also show that exposure to high doses of x-rays increases a woman's risk of getting breast cancer. Other studies indicate that taking birth control pills, exposure to certain chemicals in the environment, long-term use of hormone replacement therapy, obesity and lack of physical activity may be related to increased breast cancer risk.
- Women whose family income is above average are more likely to get breast cancer. Scientists believe this may be related to having their first child at an older age, fewer pregnancies, diet and possibly other factors shared by women in higher income groups.
- American Cancer Society confirms that use of alcohol is clearly linked to an increased risk of getting breast cancer. Women who have 1 drink a day have a very small increased risk. Those who have 2 to 5 drinks daily have about 1 1/2 times the risk of women who drink no alcohol. The American Cancer Society suggests limiting the amount you drink.
It is not yet known exactly what causes breast cancer, but it is known that certain risk factors may increase a woman's chance of developing breast cancer. These risk factors include: