Breast Cancer Health Center

Breast Cancer and Genetic Testing

Counseling is required before undergoing genetic testing for breast cancer. During this educational counseling session, a health care provider will fully explain the benefits and risks of genetic testing and answer any questions you may have.

You will also be required to sign a consent form prior to participating in genetic testing. The form is an agreement between you and your health care provider, showing that you have discussed the tests and understand how the test results might affect you and your family.

Here are some questions to consider when thinking about genetic testing:

• Am I prepared to cope with the result? Are my family members also prepared, including my children and my spouse?
• What are my goals for testing?
• How would I use my test results? What will I do differently if the results are positive, or if they are negative?
• Whom will I share my results with?
• Would a positive test result change relationships with my family?

What Happens During Genetic Testing?

You'll need to obtain a family pedigree to determine if there is a cancer development pattern within your family. A family pedigree is a chart that shows the genetic makeup of a person's ancestors, and is used to analyze inherited characteristics or diseases within a family.

After outlining the family pedigree, a blood test will be performed to determine if you have a breast cancer gene. Keep in mind that the vast majority of breast cancer cases are not associated with a breast cancer gene. In addition, scientists do not know all of the genes that can cause breast cancer, so doctors can only test you for the known genes.

When someone with a cancer diagnosis and a family history of the disease has been tested and found to have an altered BRCA1 or BRCA2 gene, the family is said to have a "known mutation." If an association between the development of breast cancer and a breast cancer gene is made, then all family members willing to participate in genetic testing are asked to give a sample of blood. For many people, knowing their test results is important because this information may help to guide future health care decisions for themselves and their families.

How Do I Interpret the Genetic Test Results?

A negative genetic test means that a breast cancer gene mutation was not identified. If genetic testing has previously identified a mutation in your family, then a negative test means you do not carry the specific mutation that was identified in your family. Therefore, your risk of developing cancer is the same as someone in the general population who has a family history of breast cancer. If a BRCA1 or BRCA2 mutation has not been previously found in your family, a negative result should be interpreted cautiously. In such cases, there is still a chance that you may be at increased risk for breast cancer due to potential mutations in genes other than those that currently can be tested for.

A positive test result means that a mutation known to increase the risk of breast and ovarian cancer was identified. Knowing your cancer risk may help guide important health care decisions for you and your family.