Genetic Tests That Make a Difference After a Breast Cancer Diagnosis

Breast cancer was once thought to be one disease. We now know there are many different types of breast cancers and that inherited genes -- as well as environmental, lifestyle and socio-economic factors -- can conspire together to elevate your risk and produce changes in breast cells that lead to different types of breast cancer.

We also used to have a one-size-fits-all approach to treating cancer. We now know that treatments need to be individualized to your unique situation, including both your genetic makeup and your tumor's genetic profile, in order to determine the best customized treatment approach for you. Genetic testing can provide this valuable information. But with the ever growing number of tests available, which tests really matter?

For women diagnosed with breast cancer, two types of genetic tests that can be especially important are genetic testing of the person for BRCA 1/2 mutations and genomic testing of the cancer, such as the Oncotype DX test.

[See: What Not to Say to a Breast Cancer Patient.]

Why BRCA 1/2 Gene Testing Matters

Most people are familiar with BRCA 1/2 testing as information to help define the level of risk for breast and other cancers and identify steps to reduce risks of developing cancer. BRCA 1/2 results can also be extremely important in determining the best treatment plan after a diagnosis.

Women with an inherited BRCA 1/2 genetic abnormality have between a 40 to 85 percent risk of developing breast cancer, and up to a 50 percent risk of ovarian cancer during the course of their lifetime. Given this high level of risk, women with a BRCA1/2 abnormality will want to take preventative steps that can substantially reduce their odds of developing these cancers.

Any woman diagnosed with breast cancer is at risk for recurrence of the original cancer. But women with a breast cancer diagnosis who have a BRCA 1 or 2 abnormality are also at a higher risk of developing a new separate breast cancer, as well as ovarian cancer, which needs to considered when deciding course of treatment.

Knowing your BRCA1/2 status can help determine if you require more frequent and advanced screenings, prophylactic surgeries and risk-reducing medications.

Having double mastectomies can reduce your risks of recurrence or the growth of a new breast cancer by up to 90 percent. Having your ovaries and fallopian tubes removed reduces your risk of ovarian cancer by 80 percent, and if done prior to menopause, can also substantially lower your risk of having a recurrence or getting another breast cancer.

Family history is all-important in weighing your odds of having a BRCA gene mutation. If any of the following applies to you, you should consider genetic testing:

-- You or a close blood relative has been diagnosed with breast cancer before the age of 50.

-- You or a close blood relative has been diagnosed with triple-negative breast cancer.

-- There are cases of both breast and ovarian cancer on one side of your family or in a single family member.

-- A male blood relative has been diagnosed with breast cancer.

[See: 7 Innovations in Cancer Therapy.]

Why Your Race and Ethnicity May Matter

There are also certain racial and ethnic populations for which genetic testing is especially important. Women with Ashkenazi (Eastern European) Jewish ancestry are at an especially high risk for inheriting a BRCA 1 or 2 genetic mutation. And African American women are at higher risk for developing a "triple negative" breast cancer, which is associated with a higher risk of having a BRCA abnormality.

About 1 in 40 Ashkenazi Jews has either a BRCA 1 or BRCA 2 gene mutation, as compared to 1 in 400 with a BRCA 1 and 1 in 800 with a BRCA 2 mutation among the general population. If you're of Ashkenazi Jewish descent, BRCA testing is very important. This is true with or without a significant family history of breast and related cancers (such as ovarian, pancreatic, melanoma, thyroid and colon cancers). But testing is particularly critical if there is a strong family history of these cancers.

African-American women are another group that can benefit from BRCA testing. They are three times more likely to have triple-negative breast cancer than the general population, an aggressive form of the disease that can be hard to treat. This type of breast cancer is also closely linked to BRCA 1/2 gene mutations, which puts them at greater risk for additional breast cancers, as well as ovarian and other cancers. Besides genetic testing, women with triple-negative breast cancer should consider participating in clinical trials to get access to new and promising medicines, which may be more effective than current treatments.

BRCA1/2 testing can be expensive. However, in most cases, insurance will cover testing for women who are at higher than average risk for having an inherited breast cancer gene. If you're uninsured, there are a variety of assistance programs that can help.

[See: 10 Lessons From Empowered Patients.]

Why Oncotype DX Testing Matters

While BRCA testing provides information about inherited genetic mutations, the Oncotype DX test analyzes the genetics of the tumor itself and is especially useful in helping to decide whether chemotherapy is needed.

No one should go through chemotherapy if it's not necessary. There are some breast cancers that absolutely require chemo treatments, but in other cases, it's not always clear. The Oncotype DX test can accurately determine the risk of cancer recurrence after initial treatment. This test can also accurately predict how likely you are to benefit from chemotherapy or if hormonal treatments such as tamoxifen are sufficient. If you're diagnosed with early stage hormone receptive positive HER2 negative breast cancer, this is an important test to discuss with your doctor.

Another newer test called the MammoPrint can also accurately assess the risk of recurrence. But, its ability to predict the benefit of chemotherapy is not as fully established.

The cost of genomic testing is usually covered by insurance if your cancer diagnosis meets the criteria for testing. For Oncotype DX, most insurance cover the test if the cancer is stage I or II and hormone receptor positive and HER2 negative. As soon as the pathology report is back, ask your surgeon if you are eligible for this test.

From my own experience with breast cancer, I know how that waiting period between diagnosis and when treatment decisions are finalized can be incredibly stressful. If you're a candidate for either BRCA or Oncotype DX testing, it's good to be tested quickly since getting results can take time and you'll want to have that information as soon as possible to reduce anxiety and uncertainty, as well as to guide treatment decisions.

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Marisa C. Weiss, M.D. is the founder, chief medical officer and guiding force behind Breastcancer.org, the world's most utilized resource for expert medical and personal information on breast health and breast cancer -- reaching 72 million people globally since it was founded in 1999. Dr. Weiss currently practices at Lankenau Medical Center in Wynnewood, Pennsylvania, where she serves as director of breast radiation oncology and director of breast health outreach. A breast oncologist with more than 30 years of active practice in the Philadelphia region, Dr. Weiss is regarded as a visionary advocate for her innovative and steadfast approach to informing and empowering individuals to protect their breast health and overcome the challenges of breast cancer. Dr. Weiss serves on the Center for Disease Control and Prevention's Advisory Committee on Breast Cancer in Young Women, and she's the author of four critically acclaimed books on breast cancer and breast health.