Risk Factors

A "risk factor" is anything that increases your risk of developing breast cancer. Controlling many of the key risk factors for breast cancer such as age, family history and medical history, is not possible however, there are some risk factors you can control, such as weight, physical activity and alcohol consumption.

Be sure to talk with your doctor about all of your possible risk factors for breast cancer. There may be steps you can take to lower your risk of breast cancer, and your doctor can help you come up with a plan. Your doctor also needs to be aware of any other risk factors beyond your control, so that he or she has an accurate understanding of your level of breast cancer risk. This can influence recommendations about breast cancer screening — what tests to have and when to start having them.

Gender: Being a woman is the most significant risk factor for developing breast cancer. Although men can get breast cancer too, women's breast cells are constantly changing and growing, mainly due to the activity of the female hormones estrogen and progesterone. This activity puts them at much greater risk for breast cancer.

Age: Simply growing older is the second biggest risk factor for breast cancer. From age 30 to 39, the risk is 1 in 233, or .43%. That jumps to 1 in 27, or almost 4%, by the time you are in your 60s. Family history of breast cancer: If you have a first-degree relative (mother, daughter, sister) who has had breast cancer, or you have multiple relatives affected by breast or ovarian cancer (especially before they turned 50) you could be at higher risk of getting breast cancer.

Personal history of breast cancer: If you have already been diagnosed with breast cancer, your risk of developing it again, either in the same breast or the other breast, is higher than if you never had the disease.

Race: White women are slightly more likely to develop breast cancer than are African American women. Asian, Hispanic, and Native American women have a lower risk of developing and dying from breast cancer. Radiation therapy to the chest: Having radiation therapy to the chest area as a child or young adult as treatment for another cancer significantly increases breast cancer risk. The increase in risk seems to be highest if the radiation was given while the breasts were still developing (during the teen years).

Breast cellular changes: Unusual changes in breast cells found during a breast biopsy (removal of suspicious tissue for examination under a microscope) can be a risk factor for developing breast cancer. These changes include overgrowth of cells (called hyperplasia) or abnormal (atypical) appearance.

Exposure to estrogen: Because the female hormone estrogen stimulates breast cell growth, exposure to estrogen over long periods of time, without any breaks, can increase the risk of breast cancer. Some of these risk factors are not under your control, such as:

 

Pregnancy and breastfeeding: Pregnancy and breastfeeding reduce the overall number of menstrual cycles in a woman's lifetime and this appears to reduce future breast cancer risk. Women who have never had a full-term pregnancy, or had their first full-term pregnancy after age 30, have an increased risk of breast cancer. For women who do have children, breastfeeding may slightly lower their breast cancer risk, especially if they continue breastfeeding for 1 ½ to 2 years. For many women, however, breastfeeding for this long is neither possible nor practical.

If you have a family history of breast cancer on either your mother's or father's side, you might have a higher risk for developing breast cancer during your lifetime. The most significant factors are if women in your family were diagnosed with breast cancer before the age of 50, if they had breast cancer in both breasts and if anyone also had ovarian cancer.

Having a family history of breast cancer does not always mean that your risk is increased. For example, if your grandmother was diagnosed with breast cancer at age 75, your risk of the disease is probably not increased. Your grandmother was most likely just one of the women who get breast cancer in advanced age as breast cancer risk increases as you get older.

Most inherited cases of breast cancer have been associated with two genes: BRCA1, which stands for BReast CAncer gene one, and BRCA2, or BReast CAncer gene two. The function of these genes is to keep breast cells growing normally and to prevent any cancer cell growth. But when these genes contain abnormalities, or mutations, they are associated with an increased breast cancer risk. Abnormal BRCA1 and BRCA2 genes may account for up to 10% of all breast cancers.

Women diagnosed with breast cancer that have an abnormal BRCA1 or BRCA2 gene often have a family history of breast cancer, ovarian cancer, or both. But it's also important to remember that most women with breast cancer have no family history of the disease.

Identifying BRCA1 and BRCA2 has led to new techniques for lowering, detecting and treating breast cancer and lowering the risk for the disease. For women who wish to be tested, we can now establish whether the two genes are normal or not.