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How BRCA Genes Work


Testing for BRCA Mutations

Learning about BRCA mutations can make anyone anxious. It's easy to think you might be susceptible to cancer because you carry one of the defective genes. In reality, only about 5 to 10 percent of all cases of breast cancer in the United States are due to inherited gene mutations [source: Susan G. Komen for the Cure]. That means almost all breast cancers develop as a result of spontaneous or acquired mutations unrelated to heredity. Most women, therefore, would not benefit from genetic testing.

How do you know? The following guidelines can help you decide whether to pursue testing for BRCA gene mutations. You should consider testing if you meet any one of the following criteria, as proposed by Susan G. Komen for the Cure, a nonprofit dedicated to ending breast cancer through research, community outreach and advocacy:

  • You were diagnosed with breast cancer at an early age.
  • Your mother, sister or daughter was diagnosed with breast cancer at an early age or ovarian cancer at any age.
  • A woman in your family, including first- and second-degree relatives (mother, sister, daughter, grandmother, aunt), has had breast and ovarian cancer.
  • Your mother, sister or daughter was diagnosed with breast cancer in both breasts.
  • Your family is of Ashkenazi Jewish descent.
  • A male in your family has had breast cancer.

A simple test can reveal whether or not the mutation exists in your cells. In most tests, a technician will take a sample of your blood. In other tests, you use an oral rinse. Each method allows the testing facility to obtain cells -- and genetic material -- from your body. At a laboratory, scientists analyze this material to look for changes in the actual BRCA genes or in the proteins coded by these genes. The testing takes three or four weeks and can cost several hundred or several thousand dollars.

If you receive a positive test result, then you know you've inherited a known mutation in BRCA1 or BRCA2. And having a BRCA mutation greatly increases your cancer risk -- up to 50 percent to develop breast cancer by age 50 and up to 87 percent to develop breast cancer by age 70 [source: Myriad Genetics]. A genetic counselor can help you assess this risk and decide what course of action to take. One option, of course, is to maintain vigilance with routine mammograms and clinical breast exams, with the goal of detecting a cancer early, when it's most treatable. Another option involves taking medications, such as tamoxifen, to reduce the risk of developing cancer. And, finally, you can take Angelina Jolie's lead and opt for prophylactic surgery -- removing as much of the cancer-susceptible tissue as possible.

There are no guarantees, however. Even with a preventive double mastectomy, breast cancer can still develop if the surgery failed to remove all of the at-risk tissue. And yet this modern era of genetics-based medicine has led to a true revolution in breast cancer detection and treatment, which is why, since 1990, there has been a 33 percent decline in breast cancer mortality in the United States [source: Susan G. Komen for the Cure].


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