BRCA1 and BRCA2 (BReast CAncer genes 1 and 2) are the best-known genes linked to breast cancer risk.
Everyone has these genes, but some people have an inherited mutation in one or both that increases the risk of breast cancer.
In addition to mutations in BRCA1/2 genes, mutations in the following genes can increase the risk of breast cancer:
Other genes are under study and may also play a role in breast cancer.
BRCA1/2 and other inherited gene mutations can be passed to you from either parent and can affect the risk of cancers in both women and men.
The risk from different types of inherited gene mutations can vary greatly. Some slightly increase breast cancer risk, while others (such as BRCA1/2) greatly increase risk. Inherited mutations known to increase the risk of breast cancer are rare in the general population.
These mutations account for only 5-10 percent of all breast cancers diagnosed in the U.S. [4,28]. So, most breast cancer are not caused by genetic factors.
Like other gene mutations, BRCA1/2 mutations are rare in the general population. In the U.S., between 1 in 400 and 1 in 800 people have a BRCA1/2 mutation .
However, prevalence varies by ethnic group. Among Ashkenazi Jewish men and women, about 1 in 40 have a BRCA1/2 mutation .
The table below shows how the prevalence of BRCA1/2 mutations varies among breast cancer survivors from different ethnic groups (in alphabetical order).
Prevalence of BRCA1 and BRCA2 mutations among U.S. women with breast cancer by ethnic group (in alphabetical order).
Less than 1%
Data not available
Caucasian (non-Ashkenazi Jewish)
Adapted from National Cancer Institute materials and Malone et al. [28,142].
Women who have a BRCA1/2 gene mutation (BRCA1/2 carriers) have an increased risk of breast cancer [29-31].
Estimates of risk are different for BRCA1 carriers and BRCA2 carriers [28,30-31]:
Women in the general population have about an 8 percent chance of getting breast cancer by age 70 . (Lifetime risk of breast cancer, up to age 85, is about 12 percent .)
This means by age 70:
These numbers represent average risk, so the risk of breast cancer for any one woman with a BRCA1/2 mutation may fall outside this range.
Note that these risks are not 100 percent. Many women with a BRCA1/2 mutation will never have breast cancer [29-31].
Together, BRCA1/2 mutations are thought to explain a large portion of hereditary breast cancers .
Most breast cancers, however, are not hereditary. A combination of factors likely causes breast cancer.
Learn about risk-reducing options for women at higher risk.
Learn about genetic testing.
Women who have a BRCA1 mutation have an increased risk of triple negative breast cancer (they tend to get breast cancers that are triple negative) [28,143-144].
Triple negative breast cancers are:
BRCA2 carriers tend to have breast cancers that are estrogen receptor-positive (ER-positive) [28,143-144].
Learn about hormone (estrogen and progesterone) receptor status, HER2 status and other factors that affect prognosis and treatment.
Learn more about triple negative breast cancer.
Learn about molecular subtypes of breast cancer.
A BRCA1/2 mutation can increase the risk of a second primary breast cancer (a second breast tumor not related to the first one) [145-150].
These tumors usually occur in the contralateral (opposite) breast rather than in the same breast as the first cancer.
For BRCA1/2 carriers, the chance of a contralateral breast cancer 10 years after diagnosis of the first cancer is about 10-30 percent compared to about 5-10 percent for breast cancer survivors without a BRCA1/2 mutation [145-150].
The lifetime risk of a second primary contralateral breast cancer is about 40-65 percent for BRCA1/2 carriers .
For a summary of research studies on BRCA1 and BRCA2 mutations and breast cancer, visit the Breast Cancer Research Studies section.
Men can also have BRCA1/2 mutations and may pass them on to their children.
Men who have a BRCA2 mutation (BRCA2 carriers) have an increased risk of breast cancer [28-29,31,151].
In men, the lifetime risk of breast cancer is 1 in 1,000 for non-carriers and about 65 in 1,000 for BRCA2 carriers [149,152].
While 5-10 percent of breast cancers in women are thought to be due to gene mutations, up to 40 percent of breast cancers in men may be related to BRCA2 mutations .
This means men who get breast cancer are more likely to have an inherited gene mutation than women who get breast cancer.
Men who have a BRCA1 mutation may also have an increased risk of breast cancer, but this link is less clear .
Learn more about breast cancer in men.
Men who have a BRCA2 mutation also have an increased risk of prostate cancer [28,152,154].
For BRCA2 carriers, the lifetime risk of prostate cancer (up to age 65) is about 15 percent .
Learn about genetic testing.
BRCA1/2 mutations increase a woman's risk of ovarian cancer .
The lifetime risk of ovarian cancer (up to age 70) is :
BRCA1/2 carriers can reduce their risk of both breast and ovarian cancer by having prophylactic oophorectomy (surgical removal of the ovaries) [141,156].
Learn more about prophylactic oophorectomy.
BRCA1/2 carriers may also have an increased risk of pancreatic cancer and some second primary cancers (new cancers that develop after a first breast cancer) .
However, data are limited and these topics are still under study.
Very low doses of radiation (such as from X-rays) do not have much, if any, impact on breast cancer risk.
While the radiation exposure during screening mammography can increase the risk of breast cancer over time, this increase is very small [157-159].
For BRCA1 and BRCA2 carriers however, there is some concern that the radiation exposure from mammography before age 30 may increase breast cancer risk to a greater degree .
This issue is under active study.
Most risk factors for breast cancer likely impact breast cancer risk in BRCA1/2 carriers just as in non-carriers.
For example, exercise and breastfeeding appear to decrease the risk of breast cancer in both BRCA1/2 carriers and non-carriers [161-162].
However, certain reproductive and lifestyle factors may affect risk differently for BRCA1/2 carriers than non-carriers.
Learn more about exercise and breast cancer risk.
Learn more about breastfeeding and breast cancer risk.
Learn more about having children, age at first childbirth and breast cancer risk.
Learn more about alcohol and breast cancer risk.
Learn more about birth control pill use and breast cancer risk.
Some support groups are tailored to BRCA1/2 carriers and people with BRCA1/2-related breast cancers.
Our Support section offers a list of resources to help find a local or online support group. For example, FORCE is an organization that has online support for women affected by hereditary breast and/or ovarian cancer.
Sharsheret has online support for Jewish women affected by hereditary breast and/or ovarian cancer.
Komen Support Resources
There is still much to learn about other inherited gene mutations that increase breast cancer risk.
Guidelines for managing risk in women with other high-risk gene mutations are less clear, but developing.
However, with genetic testing today, it is common to be tested for BRCA1/2 along with multiple other high-risk gene mutations. This is called panel or multi-gene testing. (Genetic testing for high-risk mutations is only recommended for some people.)
Because panel testing is still relatively new, the specific set of mutations assessed can vary from test to test. This can have an impact on how results are interpreted and how the information is used .
As with any genetic testing, panel testing should only be done in a medical setting after a detailed discussion of risks and benefits with a trained physician or genetic counselor .
Your family history of breast cancer and other health conditions is important to discuss with your health care provider. This information helps your provider understand your risk of breast cancer.
The Office of the Surgeon General created an online tool called “My Family Health Portrait” that you can use to create a chart of your family’s health history.
This chart may be useful when you talk with your provider about your family history of breast cancer and other health conditions.
BreastCancerTrials.org in collaboration with Susan G. Komen offers a custom matching service to help you find a clinical trial for people with a BRCA1/2 or other gene mutations.
You can also visit the National Institutes of Health's website to find a clinical trial.
Learn more about clinical trials.
*Please note, the information provided within Komen Perspectives articles is only current as of the date of posting. Therefore, some information may be out of date at this time.
Facts for Life: Genetics and Breast Cancer
Questions to Ask Your Doctor: Genes and Inherited Breast Cancer
Facts for Life: Breast Cancer in Men
2016 Research Fast Facts
Hereditary Breast Cancer
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