Genetic Tests for Breast Cancer – Who Should Be Tested?

Some people are born with abnormal (mutated) inherited genes, which may increase their risk of breast cancer and other cancers. Genetic testing for breast cancer is available for specific known gene mutations such as BRCA1 and BRCA2.

Each person should carefully consider the risks and benefits of genetic tests and fully understand what information can and cannot be gained from the results. A healthcare provider who specializes in breast cancer (an oncologist) can help with the decision to get tested and interpret the results.

Breast cancer genes

Breast cancer genes are inherited mutated genes that increase the risk of breast cancer. The risk of breast and ovarian cancer and potentially other cancers is high in women with mutations in the BRCA1 or BRCA2 gene. The risk to men with a BRCA gene is greater for breast and prostate cancer and possibly other cancers.

What are BRCA Genes?

BRCA1 and BRCA2 genes suppress cancerous (malignant) tumors. When BRCA 1 and BRCA2 are mutated, they do not work correctly. This is why people with inherited BRCA1 and BRCA2 gene mutations are at a higher risk for cancers.

There are additional gene mutations that may increase breast and other cancer risks:

PALB2, CHEK2, ATM, CDH1, PTEN, and TP53. These gene mutations are much less common and do not increase the risk of breast cancer as much as the BRCA genes. These additional genes may be included in genetic testing based on the personal and family history of an individual. If you are concerned about a personal or family history of breast cancer, talk with a healthcare professional who may refer you for genetic counseling and testing.

Who should be tested for breast gene mutations?

Expert groups have developed guidelines around who should be recommended for genetic tests for breast cancer and who should not. All healthcare professionals may not agree with the guidelines, which can be challenging to understand.

In general, two groups of people may be considered for genetic testing for inherited breast cancer mutations.

People with a personal history of breast cancer. Genetic testing in this group provides more information if:

• Breast cancer was diagnosed at a young age.
• Breast cancer is triple-negative.
• Diagnosed with a second breast cancer.
• Of Ashkenazi Jewish descent.
• A family history exists of breast cancer, ovarian cancer, prostate cancer, or pancreatic cancer.

Others who may be referred for genetic testing include people:

• With a known family history of BRCA or other gene mutation.
• With a family history of breast cancer at a young age, more than one family member with breast cancer, or breast cancer in a male family member.
• With pancreatic cancer, ovarian cancer (women), or metastatic prostate cancer (men).
• With a close family member with ovarian cancer, pancreatic cancer, or metastatic prostate cancer.

Pre and post-test counseling for genetic testing

When someone is referred for genetic testing, genetic counseling will occur before and after testing by a healthcare professional (such as a geneticist, breast surgeon, or oncology nurse). The pre-test counseling provides education about what genes are being tested and why. The post-test counseling provides the meaning of the results and recommendations for the next steps.

Results of genetic testing for breast cancer

The results of breast genetic testing will provide results that, along with genetic counseling, will help determine what actions a person and their family may take next.

What do positive results mean?

A positive result on the test for breast cancer genes means that there is a mutation known to cause hereditary breast and ovarian cancer. It does not mean that the person will develop breast cancer. It means the risk is exceptionally high. The mutation may also be passed to children.

A positive BRCA mutation has a 50% chance of being passed on each time a child is born.

With a healthcare provider, this information can help to guide treatment if cancer is already diagnosed. If cancer is not present, there can be steps taken to decrease the chance that cancer will develop and/or find cancer early if it does develop.

If family members want to get tested, their test should check for the same mutation.

What do negative results mean?

Negative breast cancer genetic test results mean that a mutation was not found for the genes tested.

A negative test for a person with cancer or a strong family history of inherited breast cancer may mean that the specific mutation is unknown. There may still be an increased risk for breast and ovarian cancer. Further testing may be recommended.

A negative test for a person who does not already have cancer does not mean they will not get cancer. It means that a mutation was not found. If no inherited risk for cancer is discovered, the risk for breast or ovarian cancer is the same as in the general population.

Direct-to-consumer testing

One direct-to-consumer test (home test) for inherited BRCA mutations is approved by the U.S. Food and Drug Administration (FDA). There are over 1,000 gene mutations identified so far in the BRCA1 and BRCA2 genes. The direct-to-consumer genetics test analyzes only three known mutations. Most people will test negative. A negative result on this at-home test does not mean that you do not have a BRCA mutation. For understanding any genetic cancer testing, consulting with a genetic counselor is strongly recommended.

A note about genetic test results

Post-test counseling is vital regardless of the result received. All test results need to be taken in context with a health and family history and interpreted by an expert. Besides positive and negative results, a genetic test may show non-informative (as for a variant of uncertain significance - VUS). A genetic counselor can help understand results and determine the best next steps for treatment or risk reduction.