Breast Cancer Risk Factors

Just being a woman is the main risk factor for breast cancer. Men get breast cancer too, but it’s about 100 times more common in women.

Having certain gene changes. As you get older, your risk of breast cancer goes up. Most breast cancers are found in women age 55 and older. Read more about screening guidelines here

About 5% of breast cancer cases are hereditary, meaning that they result directly from gene defects (called mutations) passed on from a parent. The most common ones are the BRCA1 and BRCA2 mutations. People with certain personal and/or family history patterns should be evaluated for genetic mutations. Those people should meet with members of the breast health team (genetic counselor, doctor, nurse) to talk about the likelihood of having a mutation. If the likelihood is high, then genetic testing may be offered.

It’s important to remember that about 8 in 10 women who get breast cancer do not have a family history of the disease. However, if you have a close blood relative with breast cancer, you have a higher risk. A close blood relative may be first degree (mother, sister, daughter), second degree (grandmother, aunt) or third degree (first cousin, great grandmother). Your actual risk will depend on how many relatives had breast cancer and how old they were when they were diagnosed.

If you’ve had cancer in one breast, you have a higher risk of developing a new cancer in the other breast or in another part of the same breast. This risk is even higher for younger women with breast cancer.

Overall, white women are slightly more likely to develop breast cancer than African-American women. Asian, Hispanic, and Native American women have a lower risk of developing breast cancer compared to white women, but that difference is narrowing.

Dense breasts have more glandular and fibrous tissue and less fatty tissue. A number of factors can affect breast density, such as age, menopausal status, the use of certain drugs (including menopausal hormone therapy), and pregnancy. Women with dense breasts on mammogram have a greater breast cancer risk compared to women who don’t. Unfortunately, dense breast tissue can also make mammograms less accurate, making additional testing necessary, such as an ultrasound or MRI. All patient are notified via letter regarding their breast density after their mammograms.

Some breast changes are not cancer but they do increase breast cancer risk. Conditions such as sclerosing adenosis, atypical ductal hyperplasia (ADH), atypical lobular hyperplasia (ALH) and lobular carcinoma in situ (LCIS) increase breast cancer risk to varying degrees. Be sure to discuss your risk and further options with our breast surgeon.

Starting periods at a young age (usually under 12) gives you a slightly higher risk of breast cancer because of longer estrogen exposure in your lifetime. On the other hand, starting periods at a later age may decrease your risk because of less estrogen exposure.

If you’ve had more menstrual cycles because you went through menopause later (after age 55), you have a slightly higher risk of breast cancer because of longer estrogen exposure.

If you had radiation therapy to the chest for another cancer (for example, a lymphoma), you have a significantly higher risk for breast cancer. This varies with how old you were when you had the radiation. The risk of developing breast cancer from chest radiation is highest if you had radiation during adolescence, when your breasts were still developing. If you had radiation treatment after age 40, it doesn’t seem to increase breast cancer risk.

From the 1940s through the early 1970s, some pregnant women were given an estrogen-like drug called DES, which was thought to lower their chances of miscarriage. If you were given DES, you have a slightly increased risk of developing breast cancer, and if your mother took DES during pregnancy, you may also have a slightly higher risk of breast cancer.