Emory geneticist explains how to determine if genetic testing for the hereditary breast and ovarian cancer genes – BRCA1 and BRCA2 — is right for you.
In the wake of Angelina Jolie’s disclosure that she had a preventive double mastectomy after discovering she has the BRCA1 gene mutation, many women are asking if they should get genetic testing for BRCA. As a genetic counselor and educator, I’m glad that Jolie is bringing attention to this issue. However only a small percentage of women have a BRCA1 or 2 mutation, so genetic testing is not right for everyone. Of all breast cancers, only about 5% are due to a BRCA1 or 2 mutation, while about 15% of ovarian cancers are related to mutations in one of these genes. Family history is the key to knowing if a woman would benefit from seeing a cancer genetic counselor.
Family history features which suggest you should consider cancer genetic counseling – both your mother’s and father’s relatives count:
- multiple cases of breast and/or ovarian cancer
- breast cancer diagnosed under 50
- cancer in both breasts
- both breast and ovarian cancer in the same person
- male breast cancer
- Ashkenazi (Eastern European) Jewish ancestry
As part of the genetic counseling process, the counselor will review the details of your family to assess the chance you may have a BRCA 1 or 2 mutation, as well as discuss the benefits, limitations, and implications of genetic testing. Genetic testing provides the most information for a family if someone with cancer is the first person tested. If a BRCA mutation is found, for example, in a mother with early breast cancer, we know that each of her children and siblings have a 50% risk to have also inherited the mutation. Those in the family who test negative for the identified BRCA mutation are then considered to have the same risk for breast and ovarian cancer as women in the general population – and, their children are not at risk.
For women who are found to have a BRCA1 or 2 mutation, the risks for breast and ovarian cancer are greatly increased over that of the general population. While the average woman’s lifetime risk to develop breast cancer is about 12%, the risk for a woman with a BRCA1 or 2 mutation ranges from 50-87%. Similarly, the general population lifetime risk for ovarian cancer is less than 2%, while it ranges from 40-60% for women with a BRCA gene mutation. These increased risks are why knowing that one has a mutation is so important – because increased screening and prevention strategies can dramatically reduce the chances of cancer, and save lives.
An important part of the cancer genetic counseling process involves helping women understand their medical management choices if they are found to carry a BRCA1 or BRCA2 mutation. Having all the information is a crucial step in the process of making a decision to get a double mastectomy or consider other options. Your decision should take into consideration both medical and emotional concerns and be individual to your personal situation. Many times, a woman who lost her mother or sister to breast cancer will feel differently than a woman who has a close relative who is a cancer survivor. There are alternatives to double mastectomy to consider, such as surveillance, risk avoidance and chemoprevention. Involving a medical team that includes breast surgeons, oncologists, radiologists, and gynecologists along with genetic service providers can help women determine the best approach for them.
Surveillance for breast cancer for women with a BRCA1 or 2 mutation is different than that offered to women at average risk. It involves both breast MRI and screening mammography, starting typically by age 25. Breast MRI has been shown to be much better at detecting breast cancer in young women, and in BRCA mutation carriers. Screening for ovarian cancer is unfortunately not very effective. The CA-125 blood tests and trans-vaginal ultrasounds are offered, but often fail to detect ovarian cancer in its early, curable stages. This is why preventive removal of the ovaries and fallopian tubes is strongly recommended for women who have a BRCA1 or 2 mutation. Preventive removal of the ovaries and fallopian tubes is highly effective at substantially reducing the risk not only for ovarian cancer, but also breast cancer.
Chemoprevention is also sometimes used to reduce the risk for developing cancers. Tamoxifen may reduce the risk of breast cancer in women who carry a BRCA2 mutation, though its effect with BRCA1 is less certain. Oral contraceptives use can reduce the risk for ovarian cancer by up to 50%.
There are benefits, risks and limitations to all options, but with the help of a genetic counselor working in partnership with surgeons, oncologists and others involved in cancer care and prevention, you will have the information to make the best possible decision for you and your family.
About Dr. Bellcross
Cecelia Bellcross, PhD, MS, CGC Dr. Bellcross is an assistant professor with the Emory University School of Medicine Department of Human Genetics, and the Director of the Emory Genetic Counseling Training Program. She is an ABGC board-certified (1993) genetic counselor with over 20 years of experience. She received her master’s degree in medical genetics through the University of Wisconsin-Madison Genetic Counseling Training Program in 1990, and her PhD in Population Health Sciences from U.W.-Madison in 2007. She practiced 18 years as a clinical genetic counselor specializing in cancer genetics and supervised students from the University of Wisconsin-Madison for over 10 years. Dr. Bellcross has a background in education, and recently completed a two-year ASHG fellowship in Public Health Genomics at the Centers for Disease Control and Prevention. Her areas of research interest and expertise include screening for hereditary cancers and public health genomics. She joined the faculty of Emory University in 2010 to develop and direct the new Genetic Counseling Training Program.