Q: Should I be tested for the BRCA gene?
Breast cancer is the most common cancer among women, while ovarian cancer is less common. Genetic alterations, known as mutations, are responsible for 5% to 10% of breast and ovarian cancer. The mutations most commonly related to breast and ovarian cancer occur on the BRCA1 and BRCA2 genes. Women who have a mutated BRCA1 or BRCA2 gene have an increased risk of developing breast and ovarian cancer. Men with a mutation have an increased risk of developing breast and prostate cancer.
HOW ARE THE BRCA MUTATIONS INHERITED?
BRCA1 and BRCA2 mutations are inherited from an affected parent. Each person has a 50% chance of inheriting a mutated gene from that parent. Therefore, if neither of your parents is known to have a mutated BRCA gene, the likelihood that you will have a gene mutation that increases your risk for breast or ovarian cancer is very low.
ARE OTHER CANCERS LINKED TO BRCA1 AND BRCA2 GENE MUTATIONS?
Besides the increased risk of cancers associated with mutations in either the BRCA1 or the BRCA2 gene, a BRCA2 mutation can also, but less commonly, be associated with lymphoma, melanoma, pancreatic cancer, bile duct cancer, and stomach cancer.
ARE ANY GROUPS OF PEOPLE MORE LIKELY TO HAVE A BRCA MUTATION?
Yes. Factors that contribute to increased risk of a BRCA mutation include
• A personal history of breast cancer diagnosed before age 50 years, breast cancer affecting both breasts, or breast and ovarian cancer
• Two or more close family members (grandparents, parents, siblings, and/or children) who were diagnosed with breast cancer before age 50 years
• A male relative with breast cancer
• A close family member who has had both breast and ovarian cancer or breast cancer in both breasts
• A close family member who has tested positive for a BRCA1 or BRCA2 gene mutation
• A close family member who is of Ashkenazi Jewish ancestry or Dutch, Norwegian, Icelandic, or French Canadian heritage and has a known BRCA gene mutation. If any of the above factors describes you, then you may be at increased risk of having inherited a BRCA mutation and developing certain cancers. Talk to your health care provider to determine if you qualify for testing.
HOW IS TESTING DONE?
A blood sample is sent to a laboratory. Results are usually available within a few weeks. No breast or ovarian tissue is needed to detect a mutation. If more than one family member wants to be tested, the person who is known to have (or who has had) cancer should be tested first. If this person is no longer alive, then his or her closest living relative should be tested first.
WHAT DO THE TEST RESULTS MEAN?
A negative result means that no BRCA mutation was found and that you are not at increased risk of developing any of the cancers associated with such a mutation. This does not mean that you will never develop cancer, but your risk of getting cancer is the same as that of the general population. A positive test result means that a mutation in the BRCA1 and/or the BRCA2 gene has been detected and you have an increased risk of developing certain cancers, including breast and ovarian can cer. The test does not mean that you will definitely develop one of these cancers, nor can it determine at what age you might develop them.
WHAT IF MY TEST RESULT IS POSITIVE?
Women whose test results are positive are advised to have more frequent screening, including breast examinations every 6 months and mammograms every year, and to do breast selfexaminations every month to detect breast cancer early. Screening measures for ovarian cancer in women with a known BRCA mutation include a pelvic examination; transvaginal ultrasonography; and a blood test every 6 to 12 months for a substance known as CA 125, which is released by cancer cells. Your health care provider may give you a medication called tamoxifen (Nolvadex) or raloxifene (Evista), which may help to reduce the risk of developing breast cancer. Another option for women is to undergo surgery to remove the breast (mastectomy) and ovarian tissue (oophorectomy). Removing the tissue that may become cancerous is likely to provide the greatest success in reducing the risk of breast or ovarian cancer. However, surgery does not guarantee prevention.
Men who test positive for a BRCA mutation should also undergo more regular screenings. This includes a yearly prostate examination and measurement of a substance produced by the prostate (prostate-specific antigen, or PSA), beginning at age 40 years. Men should also have breast examinations and, if possible, mammograms.
Talking to your health care provider about your risk of having a BRCA1 or BRCA2 mutation is the best place to start. He or she can help you get tested and make decisions about what to do if you have a positive test result. JAAPA