Genetic Testing for Breast Cancer

Who Should Be Tested For BRCA?

While BRCA1 and BRCA2 gene mutations may increase your odds of developing breast cancer, your odds of having either mutation are pretty small. An estimated 0.25% of the general population carries a mutated BRCA gene, or about one out of every 400 people.

For some people, though, the chances of having a BRCA gene mutation are much higher. Genes are inherited, which is why knowing your family history is important when determining breast cancer risks. If one of your parents has a BRCA mutation, you have a 50% chance of inheriting the mutated gene.

Odds can also vary depending on a person’s ethnicity. For example, people of Ashkenazi Jewish descent have a 2.5% chance of inheriting a BRCA mutation, or about 10 times the rate of the general population.

Because the overall odds are so low, most experts recommend that only people with a heightened risk get tested for BRCA mutations. Likewise, insurance companies often only cover genetic counseling and testing for individuals who are at high risk. A person could be considered at high risk for BRCA mutations if they have a family history of:

  • Breast cancer diagnosed before age 50.
  • Male breast cancer at any age.
  • Multiple relatives on the same side of the family with breast cancer.
  • Multiple breast cancers in the same woman.
  • Both breast and ovarian cancer in the same woman.
  • Ashkenazi Jewish heritage.

There are also other gene mutations besides BRCA that could increase the risk of breast cancer. The most prominent of these is PALB2. As with BRCA1 and BRCA2, testing for other genetic mutations is recommended only if you are at high risk for that particular gene.

How to Get BRCA Genetic Testing

Genetic counseling is recommended for those who are interested in being tested for breast cancer gene mutations. You can talk to a doctor about getting a referral to a genetic counselor, who can help determine whether genetic testing would make sense based on family history and risk factors. Since many genetic tests only look for one specific gene mutation, the counselor can often help determine which mutations to test for.

The genetic test itself simply involves taking a small sample of blood or saliva, which is sent to a lab for analysis. Results can take several weeks or months.

Genetic testing results are not always clear-cut:

  • A test result can be positive, meaning that the patient does carry the gene mutation.
  • A negative test result indicates that they do not have that particular gene mutation. It does not, however, rule out the possibility of having mutations in other genes. It also does not rule out the possibility of developing breast cancer. Most breast cancer cases are not hereditary, so everyone should still have an early detection plan.
  • Genetic test results can also be uncertain or ambiguous. An ambiguous test result means that a mutation has been found on the gene, but it is not yet known whether that particular mutation has any effect on the chances of developing breast cancer.

After receiving genetic test results, a patient should meet again with a genetic counselor to clarify what the results mean. Whether the results are positive, negative, or ambiguous can impact many life decisions, and a counselor can help navigate those decisions.

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