ResultsBy Mayo Clinic staff
Your test results may be positive, negative or uncertain.
Positive test result
A positive test result means that you have a harmful mutation in one of the breast cancer genes, BRCA1 or BRCA2, and a much higher risk of developing breast cancer or ovarian cancer compared with someone at average risk of developing these cancers. But a positive result doesn't mean that you'll ultimately develop cancer.
Follow-up care after a positive test result might include taking specific measures to reduce your cancer risk. What you choose to do depends on many factors - including your age, medical history, prior treatments, past surgeries and personal preferences.
To reduce your cancer risk after a positive test result, you might:
- Increase screening (surveillance). Surveillance for breast cancer if you have a BRCA mutation means having clinical breast exams every six months, and mammograms and magnetic resonance imaging (MRI) exams every year. These tests don't prevent breast cancer but may help detect it early. You may also choose to perform monthly breast self-exams to become familiar with the normal texture of your breast tissue. Potentially worrisome breast changes may be easier for you to detect earlier if you know what's normal. Surveillance for ovarian cancer includes having semiannual pelvic exams, transvaginal ultrasound imaging and blood tests to measure your cancer antigen 125 levels.
- Use oral contraceptives. Oral contraceptive use has been shown to reduce ovarian cancer risk in BRCA mutation carriers. Your risk of breast cancer goes up slightly if you use oral contraceptives for more than five years, however.
- Take a medication to reduce your risk of cancer (chemoprevention). Tamoxifen reduces the risk of developing breast cancer by about 50 percent in women who are at increased risk of the disease. Some studies have shown that tamoxifen may help lower the risk in women with a BRCA gene mutation. Another possible preventive medication is raloxifene (Evista), which also helps reduce the chance of breast cancer in postmenopausal women at high risk, though it hasn't been studied specifically in women with BRCA mutations.
- Undergo preventive surgery. Preventive (prophylactic) mastectomy — surgical removal of healthy breast tissue — reduces breast cancer risk by about 90 percent. Removal of healthy fallopian tubes and ovaries (preventive salpingo-oophorectomy) reduces breast cancer risk by 50 percent in premenopausal women, and it reduces ovarian cancer risk by more than 90 percent in both pre- and postmenopausal women.
Preventive surgery doesn't eliminate all cancer risk. It's possible that cancer still might develop in any tissue that couldn't be removed through surgery.
Negative or uncertain test result
A negative test result means that no BRCA gene mutation was found. However, drawing a conclusion about your cancer risk is still a bit difficult. The test result is considered a "true negative" only if it finds that you don't carry a specific BRCA mutation — that is, one that's already been identified in a relative of yours. In addition, a negative test result, while reassuring with regard to reducing the risk of a hereditary breast cancer, doesn't eliminate the chance of developing a nonhereditary breast cancer. You still have the same cancer risk as that of the general population.
Although the BRCA gene test can detect the majority of mutations in the BRCA1 and BRCA2 genes, it's possible that you could have a gene mutation that the test wasn't able to detect. Or you may be at high risk of hereditary cancer if your family carries a high-risk gene mutation that researchers haven't yet identified and developed a test for.
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