Some risk factors (such as obesity, smoking and drinking alcohol) can be avoided. But most risk factors (such as having a family history of breast cancer) cannot.
Studies have identified the following risk factors for breast cancer:
- Age: The chance of getting breast cancer increases as you get older. Most women are over 60 years old when they are diagnosed. But it is important to remember that breast cancer can occur in women in their early 20's.
- Personal health history: Having breast cancer in one breast increases your risk of getting cancer in your other breast. Also, having certain types of abnormal breast cells (atypical hyperplasia, lobular carcinoma in situ [LCIS], or ductal carcinoma in situ [DCIS]) increases the risk of invasive breast cancer. These conditions are found with a breast biopsy.
- Family health history:
Your risk of breast cancer is higher if your mother, father, sister, or daughter had breast cancer. The risk is even higher if your family member had breast cancer before age 50. If other members of your mother's or father's family have had breast cancer or ovarian cancer, your risk may be higher.
- Certain geneticchanges: Changes in certain genes, such as BRCA1 or BRCA2, substantially increase the risk of breast cancer. Tests can sometimes show the presence of these rare, specific gene changes in families with many women who have had breast cancer, and healthcare providers may suggest ways to try to reduce the risk of breast cancer or to improve the detection of this disease in women who have these genetic changes.
- Radiation therapy to the chest: Women who had radiation therapy to the chest (including the breasts) before age 30 are at an increased risk of breast cancer. This includes women treated with radiation for Hodgkin lymphoma. Studies show that the younger a woman was when she received radiation treatment, the higher her risk of breast cancer later in life.
- Reproductive and menstrual history:
- The older a woman is when she gives birth to her first child, the greater her chance of breast cancer.
- Women who never give birth are at an increased risk of breast cancer.
- Women whose first menstrual period occurred before age 12 are at an increased risk of breast cancer.
- Women who undergo menopause after age 55 are at an increased risk of breast cancer.
- Women who take menopausal hormone therapy for many years have an increased risk of breast cancer.
- Race: In the United States, breast cancer is diagnosed more often in white women than in African-American/black, Hispanic/Latina, Asian/Pacific Islander, or American Indian/Alaska Native women. But it may be important for young black women to be aware that 35 percent of breast cancer develops in African-Americans before the age of 50.
- Breast density: Breasts appear on a mammogram (breast x-ray) as having areas of dense and fatty (not dense) tissue. Women whose mammograms show a larger area of dense tissue than is average for their age are at increased risk of breast cancer. It remains unclear whether women with dense breasts are at higher risk of developing cancer, or whether the density makes cancers more difficult to detect.
- History of taking DES: DES was given to some pregnant women in the United States between about 1940 and 1971. (It is no longer given to pregnant women.) Women who took DES during pregnancy may have a slightly increased risk of breast cancer. The possible effects on their daughters are under study.
- Weight beyond menopause: The chance of getting breast cancer after menopause is higher in women who are overweight or obese.
- Physical activity: Women who are physically inactive throughout life may have an increased risk of breast cancer.
- Alcohol use: Studies suggest that the more alcohol a woman drinks, the greater her risk of breast cancer.
- Tobacco use: Smoking within the first five years of your first period (during teenage-early 20s) increases your risk of breast cancer and increases your risk of pre-menopausal breast cancer, which is harder to find.
Having a risk factor does not mean that a woman will get breast cancer. Most women who have risk factors never develop breast cancer.
Source: National Cancer Institute