what other risk factors you may already have (the New York study also suggests that your risk is influenced by environmental factors). For example, if you have a BRCA mutation and know at least one person in your family with a BRCA mutation who has had breast cancer, by the time you are 80 years old, your risk of developing breast cancer will be 82 percent, according to the New York Breast Cancer study. Changes in other genes may also increase the risk of inherited breast cancer, such as the ATM, CHEK2, p53, and PTEN gene mutations. Certain mutations can also raise your risk of ovarian cancer if you have a family history of the disease. A genetic counselor can help you interpret the results of your test.
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How do I get tested?
It’s important to talk to a counselor first. During your visit, the counselor will ask you about your family medical history and help you determine whether you would benefit from a genetic test. If you opt for a full sequencing of both BRCA genes to check for any mutation that could occur in either gene, it will cost you about $2,400.
You’ll have a small amount of blood drawn for either type of test. Your blood will be sent to the laboratory, where technicians will extract DNA from your blood cells and run the test you chose. Depending on the lab and the type of test, it can take from several weeks to several months to get the results, according to the National Cancer Institute. The information will be mailed to your doctor or counselor, who will explain the results to you and help you figure out what you need to do next.
Does a negative result mean that I won’t get breast cancer?
Unfortunately, no. Recent studies suggest that the two BRCA genes together account for only 40 to 50 percent of hereditary breast cancer. (Previous estimates pegged them as culprits 90 percent of the time.) That means there are other cancer-related genes out there that the current test doesn’t see. In addition, although breast cancer does tend to run in families, researchers believe that only a minority of cases — about 5 to 10 percent — are due to known BRCA genetic mutations. That means that 90 to 95 percent of new breast cancer cases are unrelated to the genetic changes that can be discovered in tests. About 70 percent of women who develop breast cancer don’t have any known relatives with the disease. Most cancers develop because of mutations acquired during your lifetime, due to things like years of exposure to ultraviolet rays and occasional random mistakes that slip by your cells’ DNA repair machinery.
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What can I do if the test is positive?
Increasing your vigilance could certainly help. Ask your doctor how often you should be getting mammograms and clinical breast exams. (If you’ve inherited a mutation that increases your risk for ovarian cancer, ask about getting a transvaginal ultrasound screening at least once a year, along with other blood tests.)
For women with true BRCA mutations, some doctors recommend bilateral prophylactic mastectomies — that is, the removal of both healthy breasts as a precaution. Surgeons can’t remove every cell that could potentially become cancerous, however. This operation may decrease your risk by more than 90 percent, but that still leaves you with a 10 percent risk after undergoing surgery. There is also some evidence that removing healthy ovaries (prophylactic oophorectomy) decreases the risk of breast and ovarian cancer by up to 50 percent. However, the surgery cannot remove all the tissue that is at risk, and some women have developed a type of cancer similar to ovarian cancer even after having prophylactic surgery, according to the National Cancer Institute.
Another downside to genetic testing: some women have had their insurance rates raised or their coverage dropped after they had a test, regardless of the result. You might consider paying for the test yourself. However, if you start a new health or life insurance policy, you may be asked if you’ve ever had genetic testing done. If this happens to you, be aware that a federal law is in place to help guard your privacy. The Genetic Information Nondiscrimination Act of 2008 sets uniform standards to help protect people from possible discrimination.