A risk factor is anything that may increase a person’s chance of developing a disease. It may be an activity, such as smoking, diet, family history, or many other things. Different diseases, including cancers, have different risk factors.
But risk factors don’t tell us everything. Having a risk factor, or even several, does not mean that you will get the disease. Most women who have one or more breast cancer risk factors never develop the disease, while many women with breast cancer have no apparent risk factors (other than being a woman and growing older). Even when a woman with risk factors develops breast cancer, it is hard to know just how much these factors might have contributed.
Any woman may develop breast cancer. However, the following risk factors may increase the likelihood of developing the disease.
Risk factors that cannot be changed:
- Breast cancer occurs nearly 100 times more often in women than in men.
- Race or ethnicity. It has been noted that white women develop breast cancer slightly more often than African-American women. However, African-American women tend to die of breast cancer more often.
- Two out of 3 women with invasive cancer are diagnosed after age 55.
- Personal history of breast cancer.
- Previous breast irradiation.
- Family history and genetic factors.
- Benign breast disease. Women with certain benign breast conditions (such as hyperplasia or atypical hyperplasia) have an increased risk of breast cancer.
- Dense breast tissue. Older women with high dense breast tissue are at increased risk.
- Diethylstilbestrol (DES) exposure. Women who took this drug while pregnant (to lower the chance of miscarriage) are at higher risk.
- Early menstrual periods. Women whose periods began early in life (before age 12) have a slightly higher risk of breast cancer.
- Late menopause. Women are at a slightly higher risk if they began menopause later in life (after age 55).