Genetic testing


If you are newly diagnosed with breast cancer, knowing whether you carry a gene mutation may help you make important treatment decisions.

If you’ve finished treatment, you might think genetic testing isn’t necessary. You may see it as an extra test because your results can’t change the treatments you’ve had already.

While this may be true, many women choose to have genetic testing even after they complete treatment to better understand their risk for a second breast cancer or ovarian cancer. Testing can also help family members know more about their own risk of developing these cancers.


Why get genetic testing?

Having a family member who carries a gene mutation greatly increases the chance that you do. Your test results may tell your siblings, children or grandchildren that they may be at high risk for breast cancer. If you test positive for a mutation, your family members’ insurance providers may be more likely to cover the cost of genetic testing, especially if they have not been diagnosed with breast cancer already.

Learning your hereditary cancer risk after completing treatment may allow you to consider risk management options to help protect you from new cancers. Some women choose to have risk-reducing surgeries after learning they carry a BRCA mutation.

Getting tested can also help scientists understand more about how mutated genes relate to developing breast cancer and to its treatment. Women who have gene mutations are needed to participate in breast cancer research that may one day shape new treatments or aid in prevention.

Top reasons why women decide to get genetic testing:

  • To be proactive about their health
  • To make informed treatment or prevention decisions
  • To hand down information to their sons and daughters
  • To inform immediate family, such as sisters, brothers, aunts, etc., of the possibility of inherited gene mutations
  • To make decisions about family planning and fertility preservation that might be impacted by cancer treatment or ovarian cancer
  • Because they have a family history of breast cancer and want to know more
  • Because they were young at diagnosis and the cancer is aggressive
  • Because others in their family want to know about their own risk
  • Because their doctor or genetic counselor recommended it
  • Because sometimes, knowing more means fearing less

The testing process

The testing process for breast cancer-related gene mutations is a simple blood or cheek-swab test. A saliva (spit) sample also may be collected.

Blood may be drawn at a lab or at your doctor’s office or a hospital. The blood is taken by needle, usually from a vein on the inside of your elbow. If you have a cheek-swab test, your doctor will roll a cotton-tipped swab along the inside of your cheek to collect a sample. If you are asked for a spit sample, you will cleanse your mouth with mouthwash and spit into a cup.

Your sample will then be sent to a lab that will search for gene mutations. A report will be returned to your doctor or genetic counselor. It may take 2 to 3 weeks, or more, for your test results to come back. If you are newly diagnosed or need your results to make treatment decisions, you may choose to rush the test results, usually for an extra cost.


Tests you can get

There are several types of tests to search for mutations thought to cause breast cancer. Testing can be done in a few different ways. Your genetic counselor can explain which type of testing is best for you.

Depending on your personal and family history of cancer, and whether a gene mutation has been identified in your family in the past, your counselor may recommend testing of BRCA1 and BRCA2 or other genes. He or she also may recommend testing for other genes or for a panel of genes, depending on your family history.

The three most common tests are:

  • Comprehensive testing of BRCA1 and BRCA2
  • Single-site testing for a mutation already known to be in your family, or for a more limited number of mutations like the BRCA1 and BRCA2 mutations found in the Ashkenazi Jewish population
  • Gene panel tests, which look for many mutations in many genes all at once

If your or your family’s history suggests there may be a mutation in a specific gene, testing of just this gene may be done.


A note on at-home testing

In recent years, direct-to-consumer genetic tests have become available.

You may see these tests advertised on TV or available online. They can be delivered directly to you by mail and don’t need to be ordered by a doctor or other healthcare professional. An at-home genetic test may require you to visit a health clinic to have a blood sample taken and sent to the lab that sells the test, or it may only ask you to send a saliva sample to the lab by mail, without seeing a doctor first.

An at-home test may cost less or feel like less of a burden. But if you choose at-home testing, you won’t have guidance from a specially trained professional when you get your results. Having a genetic counselor available to discuss whether you need testing and how your test will be carried out can help you make treatment decisions and navigate emotional reactions once your results are back.

If you have questions or concerns about at-home testing versus testing in the clinic, talk with your oncologist, or ask to speak with a social worker, genetic counselor or patient navigator at your medical center.


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Reviewed and updated: August 31, 2015

Reviewed by: Mark Robson, MD


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