A few years back, Angelina Jolie revealed that she had a gene mutation that greatly increased her risk of breast cancer. Her story pushed the issue to the headlines.
The link between family history and the disease was well known even before the actress made her announcement. Still, it sparked growing interest in genetic testing for breast cancer, leaving many women to ask if it might be right for them.
Here are questions and answers about this from the nonprofit Susan G. Komen foundation to fight breast cancer, which organizes the Triangle's Race for the Cure.
Q. What's essential to know?
A. Every cell in your body contains genes. Sometimes, people are born with an error in one of these genes called a mutation. Some gene mutations are linked to breast cancer, such as BRCA1 and BRCA2.
A mutated gene can be inherited from either the mother or father. This inherited mutation may increase a woman's risk of breast or ovarian cancer.
However, most breast cancers are not due to family history or genetic factors, such as BRCA1/2 mutations.
Genetic testing is recommended only for certain people at high risk based on their personal or family history of the disease. Testing should be done in a medical setting with a trained physician or genetic counselor.
BRCA1/2 are the most well-known gene mutations and greatly increase breast cancer risk. However, women with these mutations can often take steps to manage or lower their risk.
Expanded panel testing for BRCA1/2 and other high-risk mutations is becoming more common and can provide useful information about breast cancer risk.
Q. How many breast cancers are caused by family history and genetics?
A. The risk from different types of inherited gene mutations can vary greatly. Some slightly increase breast cancer risk, while others (like mutations in the well-known BRCA1 and BRCA2 genes) greatly increase risk.
Although family history and genetics are important risk factors for breast cancer, they account for only 5 to10 percent of all cases in the United States. This means most breast cancers are not due to genetic factors, such as BRCA1/2 mutations.
Q. How common are BRCA1/2 mutations?
A. Thankfully, they're not common. About 1 out of every 400 to 800 people in this country (or less than 1 percent) has a BRCA1/2 mutation. In people of Ashkenazi Jewish descent, the rate is higher, around 1 in 40, or 2.5 percent.
The percentage of people with other high-risk gene mutations is less well understood.
Q. How much does a BRCA1/2 mutation increase risk?
A. Breast cancer risk varies by BRCA1/2 mutation. Here's a rundown:
- Women with a BRCA1 mutation have a 55 to 65 percent chance of developing breast cancer by age 70.
- Women with a BRCA2 mutation have about a 45 percent chance of developing breast cancer by age 70.
These compare to an 8 percent chance of developing breast cancer by age 70 for women at average risk. (Lifetime risk of breast cancer, up to age 85, is about 12 percent.)
While these risks are very high, a BRCA1/2 mutation does not guarantee that a woman will develop breast cancer.
Women with BRCA1/2 mutations are also at risk for ovarian cancer.
Q. Who should consider genetic testing?
A. Genetic testing is recommended only for people whose personal or family history of breast cancer shows they might have a genetic mutation that increases the risk of breast cancer.
For example, testing is recommended if:
- There is a known BRCA1/2 mutation in your family.
- You had breast cancer at age 50 or younger.
- A woman in your family had breast cancer at age 50 or younger.
- A woman in your family had breast cancer in both breasts.
- A woman in your family had ovarian cancer.
- A man in your family had breast cancer.
- Your family is of Ashkenazi Jewish descent and you or someone in your family had breast cancer.
Websites such as the Centers for Disease Control and Prevention's Know: BRCA can help you work through your family history to see if testing may make sense.
Q. What are the different types of genetic testing?
A. Traditionally, genetic testing looked at only one or two genes, focusing most often on BRCA1/2.
Increasingly common today is testing for BRCA1/2 along with other high-risk gene mutations (called panel or multi-gene testing).
The evidence on panel testing is still developing. However, some studies have shown it can accurately find BRCA1/2 and other important high-risk mutations in order to help manage a person's breast cancer risk.
Q. What if I have a gene mutation that increases risk?
A. Women with a BRCA 1/2 mutation typically have three options:
- Get more intensive breast cancer screening.
- Take risk-reducing medications, like tamoxifen or raloxifene.
- Have preventive surgery to remove both breasts and/or the ovaries.
Each choice has benefits and drawbacks, which should be discussed in detail with a physician.