Is Genetic Testing for Breast Cancer Right for You?

05/06/2015 12:26 pm ET | Updated May 06, 2016

Susan K. Boolbol, MD
Chief, Division of Breast Surgery
Mount Sinai Beth Israel

For most women, the average risk of developing breast cancer is about 12 percent. However, if you have a mutation on either of the two most common genes associated with breast cancer -- BRCA1 and BRCA2 -- that risk can jump as high as 80 percent. While it's natural to wonder if you might have inherited an abnormal BRCA gene from one of your parents, it's also important to remember that only about 5-10 percent of breast cancers are due to hereditary mutations; the overwhelming majority of women with breast cancer have no family history of the disease. That's why genetic testing is recommended only for people whose family history or other factors suggest the presence of a gene mutation.

Consider Genetic Testing If...

The following factors increase an individual's likelihood of having inherited a BRCA gene mutation. If any of them apply to you, your doctor may refer you to a cancer genetic counselor to help determine whether genetic testing is appropriate in your case. If so, the results can help you make more informed decisions about your breast health, including treatment if you have already been diagnosed with breast cancer.

  • A family history of breast cancer, especially in first-degree female relatives (those with whom you share 50 percent of your genes: your mother, sisters, daughters). However, if you don't know your family history beyond your parents or grandparents, or if there are few women in your family--for example, if you have a small family, or a large family but with few first-degree female relatives-- a negative family history for breast cancer may not tell us much. Keep in mind that while family history is important, it is not the only factor we consider.
  • Breast cancer diagnosis before age 50 in yourself or female relatives. Your mother's being diagnosed at age 30, for example, would be much more significant than if she were diagnosed at age 85.
  • Breast cancer diagnosis in a first-degree male relative (father, brothers, sons) of any age. Yes, men do get breast cancer. In fact, the American Cancer Society estimates that 2,350 new cases of invasive male breast cancer will be diagnosed this year.
  • A history of ovarian cancer in the family. Ovarian cancer, which is rare compared to breast cancer, is a red flag for BRCA genetic mutations.
  • Being of Ashkenazi Jewish descent.
  • Having "triple negative" breast cancer. This pertains to the cancer's biology and means that estrogen, progesterone, and HER2 (a type of gene that can influence breast cancer) play no role in the cancer's development.
  • Having breast cancer in both breasts, either simultaneously or years apart. Cancer in the second breast does not mean the first cancer has spread; it is a different, new cancer.
  • If you are a male diagnosed with breast cancer. Genetic mutations are equally important for men.

Genetic testing is done through a simple blood test or, in some cases, a swab of the inner cheek. When considering genetic testing for BRCA mutations, it is ideal to see a cancer genetic counselor to discuss your hereditary cancer risk, possible implications of test results, and other important issues. If cancer genetic counselors are not available in your area, ask your doctor to refer you to a service that provides such counseling over the phone.

Why Get Tested?

Knowing that you have a genetic mutation for breast cancer empowers you to make an informed decision about how to reduce your risk. If you don't have breast cancer but find out you have an abnormal BRCA gene, one option is to have a double mastectomy (surgical removal of both breasts) as a preventive measure (as actress and humanitarian Angelina Jolie did a few years ago). Another, equally valid, option is to be followed much more closely, with the goal of catching cancer early should it develop. This would involve more frequent imaging, including mammograms, ultrasound, and MRI scans of the breasts. If you have already been diagnosed with breast cancer, learning prior to surgery that you have a mutation may help you decide whether to get a lumpectomy, single mastectomy, or double mastectomy.

In my practice, I have seen women who are candidates for genetic testing decide against it because they are, understandably, afraid and don't want to know the answer. Getting tested is a personal decision; however, when fear is a motivating factor, I encourage my patients to consider the following:

  • Just because you don't know whether you have a genetic mutation doesn't mean it doesn't exist.
  • Knowledge is power. Knowing your BRCA status can help you make an informed decision about your options for breast cancer risk reduction or treatment.
  • Knowing that you have an abnormal BRCA gene can be the key to information for your whole family, particularly your children and grandchildren, who would have a 50 percent and 25 percent chance, respectively, of inheriting a genetic mutation. If you don't want to do it for yourself, consider getting tested for them.