Cancer is a group of diseases caused by uncontrolled growth and division of abnormal cells. Breast cancer is cancer that develops in breast cells. Though environmental and lifestyle factors play a role in developing cancer, your genetics can increase your risk of developing certain types of cancer, including breast cancer.

Mutations (abnormal changes) in two genes known as BRCA1 and BRCA2 are known to increase a person’s risk of having breast cancer during their lifetime. Every person has BRCA1 and BRCA2 genes. These genes help your body create proteins to repair damaged DNA, particularly in your breasts and ovaries.

While not everyone with mutations in their BRCA1 or BRCA2 genes will develop breast cancer, having these mutations (also called variants) does greatly increase your chance of developing breast cancer as well as other cancer types, like ovarian, prostate, and pancreatic cancers.

A gene test for BRCA genetic mutations is available to find out if you have an increased risk of developing cancer.

According to research published in 2005, about 1 to 2 percent of breast cancers are linked to mutations in the BRCA1 or BRCA2 genes. Though this is a relatively small percent, according to the American Cancer Society up to 7 in 10 women with a BRCA gene mutation will develop breast cancer by the time they’re 80 years old.

Men with a BRCA2 mutation also have an increased risk of developing male breast cancer.

A BRCA blood test is one tool that can be used to learn about your cancer risk. If you test positive for mutations in the BRCA1 or BRCA2 genes, you may need to be screened for cancer more frequently or at an earlier age.

Depending on your family history, a positive result may also mean that you might want to consider taking steps to lower your risk of getting breast cancer, such as lifestyle changes, or preventive surgeries like a mastectomy. The results of the test can be used to help guide future treatments if you do end up having breast cancer.

The U.S. Preventive Services Task Force (USPSTF) provides guidelines for when a person should consider having a BRCA blood test. Currently, testing is not recommended for the general public. In general, a BRCA test is recommended if:

  • you’ve had multiple blood relatives who have been diagnosed with breast cancer or ovarian cancer (or both)
  • you have blood relatives who had breast cancer diagnosed before age 50
  • someone in your family has had a BRCA-related cancer
  • you’ve already been diagnosed with either breast, ovarian, fallopian tube, or peritoneal cancer
  • a man in your family has had breast cancer
  • you’re of Ashkenazi Jewish (Eastern European) heritage

The BRCA blood test does not carry any physical risks, but it could have a psychological impact, such as stress or anxiety about the test results. Genetic testing can sometimes be expensive. If a doctor or genetic counselor orders the test, your insurance will likely cover the cost, but this may not be the case for certain health plans.

There is no special preparation necessary for a BRCA gene test. You can eat and drink normally before the test.

During the test, a healthcare professional will insert a needle into a vein in your arm to draw the blood sample needed for testing. You may feel a pinch or stinging sensation when the needle is inserted and the blood is withdrawn. The test only takes a few minutes, and you can go about your normal activities afterward.

The sample is then sent to a lab for further analysis. Your doctor or a genetic counselor will go over the results with you when they are available, usually within a few weeks.

At-home testing

At-home testing may be offered by some companies, such as 23andMe.

These companies use a sample of saliva rather than blood sample to test for BRCA mutations. Most of these companies allow you to order a kit online, and once received, you simply mail them back a saliva sample for analysis. However, these services may have drawbacks. For example:

  • they may be limited in their ability to detect all the mutations known to occur in the BRCA1 and BRCA2 genes.
  • they typically do not offer genetic counseling
  • they do not inform you if additional genetic testing is needed
  • you may still need to confirm the results with a clinical laboratory

Even with the online testing, it’s important to speak to a medical professional to learn what your test results mean.

The results of a BRCA gene test will fall in one of three categories:

  • A negative result means that no known harmful mutations in your BRCA1 or BRCA2 genes were found.
  • A positive result means a gene mutation that is known to contribute to cancer risk was found. The result may be described as pathogenic (disease-causing). A positive result means that your risk is increased, but not everyone with a BRCA gene mutation will go on to develop breast cancer. Some people who inherit a harmful BRCA1 or BRCA2 gene variant never develop cancer, but they may pass the variant to their children.
  • In a small number of cases, a test may also find variants of uncertain significance (VUS). These are mutations that have not previously been associated with a higher cancer risk. After further research, studies are conducted, and most VUS are later reclassified as benign or negative. When a VUS is reclassified, the laboratory that performed your testing may send a revised test report to your doctor or genetic counselor with an explanation, but some laboratories do not follow up. If you receive a VUS test result, it’s important to regularly ask for any new information from the testing provider in case that particular VUS is reclassified as a harmful or likely harmful variant.

A genetic counselor is a medical professional who is trained to interpret information about how genetics play a role in developing diseases, such as cancer. Your primary care doctor can help you understand if you need genetic counseling.

If genetic testing is recommended, talking with a genetic counselor is very important. They can assess your family’s history of cancer and provide you with information about the risks and benefits of genetic testing. They can also explain what exactly your results mean as well as talk through potential next steps with you.

BRCA gene tests are used to help you learn if you have any inherited mutations in your BRCA1 or BRCA2 genes. Mutations in these genes are known to greatly increase your risk of developing breast cancer, among other cancers.

If you have a personal or family history of cancer, meet with your doctor to help better understand your risk of breast cancer and if you may benefit from genetic testing.

From there, your doctor may recommend a genetic counselor who can advise you on BRCA gene testing or other tests to assess your personal cancer risk.