October 2016 Ask the Expert: What’s New in Genetic Testing
Do people in your family have breast cancer, including you? Were you young when you were diagnosed? Does a man in your family have breast cancer?
You may have heard that certain risk factors suggest that the cancer may be related to a gene mutation, an error in a gene’s DNA. Maybe you’ve already had genetic testing and know you carry a mutation. Or, maybe you’ve thought about getting a genetic test, but you’re not sure which kind of test is right for you.
Genetics researchers are constantly finding new connections between the way genes behave and their role in causing breast cancer and other cancers. In October, Living Beyond Breast Cancer expert Marianne Lotito, MS, LCGC, a genetic counselor from Overlake Medical Center in Bellevue, Washington, answered your questions about what’s new in breast cancer genetic research, what your results may mean, when to get testing, and what to do once you have your test results.
Remember: we cannot provide diagnoses, medical consultations or specific treatment recommendations. This service is designed for educational and informational purposes only. The information is general in nature. For specific healthcare questions or concerns, consult your healthcare provider because treatment varies with individual circumstances. The content is not intended in any way to substitute for professional counseling or medical advice.
Visit our Genetics and Family Risk page to learn more about breast cancer genetics, and take a short quiz to find out whether you may wish to speak with your provider about your risks for hereditary breast or ovarian cancer.
Our October Expert:
Marianne Lotito, MS, LCGC
This Ask the Expert residency is sponsored by Myriad.
Knowing and understanding the cancer history in your family – who has been diagnosed with cancer, what type of cancer, and the age at which it was diagnosed – is the first step in figuring out if you have an elevated risk for hereditary breast cancer. The “red flags” or indications of possible hereditary breast cancer include cancer at an earlier age than average, certain rare cancers, and multiple people on the same side of the family who have cancer. For example, consideration of possible hereditary breast and ovarian cancer may include:
- personal or family history of breast cancer diagnosed at or under age 45
- an individual diagnosed with ovarian cancer at any age
- a male relative with a diagnosis of breast cancer
One online tool that may be of assistance in gathering and assessing your family history of cancer is hereditarycancerquiz.com.
In addition to BRCA1 and BRCA2, there are multiple other genes that can be associated with elevated risk for both breast and ovarian cancer when a mutation in those genes is passed on in the family. Studies have shown that about 10 percent of breast cancer and 15-20 percent of ovarian cancer may be hereditary and that mutations in BRCA1 or BRCA2 may account for 47-65 percent of those hereditary breast and ovarian cancers. If a healthcare provider only looks for mutations in BRCA1 and BRCA2, clinically significant mutations that may help to personalize management and aid in early detection or cancer prevention may be missed.
Variation in genes among people is very common. A variant of uncertain significance, or VUS, is a change in the normal sequence of DNA within a gene. The association of this change with disease (in this case, cancer risk) is unclear at this time. A VUS may indicate a risk for hereditary cancer, but it also may not. For that reason, it is recommended that the care you receive be based on the cancer history in your family, not on the finding of the VUS.
Over the past few years, genetic testing technology has improved to allow healthcare providers to test for genes beyond BRCA1 and BRCA2. Patients who had genetic testing for BRCA1 and BRCA2 a few years ago should speak with a healthcare provider to determine if further testing for additional genes is warranted at this time. Newer technology called Next Generation Sequencing allows the lab to test multiple genes at one time.
Research is allowing laboratories to better understand the exact impact a mutation, or change in the DNA, may have on cancer risk. With further studies and research, results that are originally classified as “variants of uncertain significance” may be updated to negative or positive results.
The opportunity to prevent cancer in relatives of a patient who has tested positive for a mutation is a major benefit of genetic counseling and testing for hereditary cancer. It is important to share the specifics of your results with relatives so they can be tested for the same mutation, called single-site analysis. A healthcare provider can assist with identifying which relatives may wish to proceed with testing and help to connect your relatives with a healthcare provider who can explain the benefits and help them proceed with testing.
It’s natural to be concerned about passing on a BRCA mutation to your children. There is a 50 percent chance that each child will inherit the mutation. Preimplantation genetic diagnosis (or PGD) can be used with in vitro fertilization to ensure the BRCA gene mutation has not been passed on to biological children. PGD for BRCA mutations is a personal decision that should be made with your healthcare team, partner and family members.
ABC News recently shared the story of a family who underwent PGD related to a BRCA mutation.
One in 40 men and women of Ashkenazi Jewish decent carries a mutation in BRCA1 or BRCA2 (compared to an estimate of 1 in 350 to 440 in non-Ashkenazi Jewish people). Genetic testing of Jewish women can lead to intensive screening and preventative surgeries related to breast and ovarian cancer when a mutation is found. For this reason, it would be reasonable for the general population of Jewish women to consider genetic testing for hereditary breast and ovarian cancer.
There are multiple genes that can lead to elevated risk for breast cancer when a mutation is present. The genes that most commonly have a mutation and are associated with personal and family history of breast cancer include BRCA1 and BRCA2. Women with mutations on those genes have a breast cancer risk in the range of 43-87 percent. There are other high-risk breast cancer genes that less commonly have mutations in them. Women with mutations in moderate-risk genes including ATM, CHEK2, and PALB2 have breast cancer risks in the range of 17 to 58 percent. These examples are a few of the genes that can be associated with elevated risk for breast cancer. A healthcare provider can give you more information and assist you with risk assessment and testing.
There are three categories for options to manage breast cancer risk: increased surveillance, medicines to reduce cancer risk, and preventative surgery. Increased surveillance involves frequent monitoring of the health of your breasts. It can include breast imaging every 6 months, alternating between mammogram and MRI. People with a mutation should start surveillance at age 25, or at least 10 years earlier than the age at which the youngest person in the family was diagnosed with breast cancer. Medicines such as hormone blockers (including tamoxifen and aromatase inhibitors) have been shown to reduce the risk for breast cancer by just over 50 percent. A risk-reducing mastectomy, sometimes called a preventitive or prophylactic mastectomy, involves surgical removal of breast tissue prior to a cancer diagnosis. It can reduce the risk of breast cancer by as much as 95 percent or more.
When a person has a mutation that relates to elevated risk for breast cancer, the risk to develop breast cancer (or other cancers associated with that gene mutation) is not 100 percent. For this reason, there can be people in the family who inherit a gene mutation but are never diagnosed with cancer. Also, the size of the family and number of female relatives can skew the cancer history in the family (for example, if there are few women in the family and more men).
Analysis of DNA can be performed on both saliva and blood samples. For test results to be completed, the time that it takes depends on the number of genes analyzed and the technology that is used. For most labs, the turnaround time to get results back to the healthcare provider and patient is usually in the range of 1-4 weeks.
Questions regarding privacy of genetic information are quite common, and often people will worry that genetic information will affect their health insurance and employment. In May of 2008, a federal law called the Genetic Information Nondiscrimination Act (or GINA) was signed to prevent discrimination from health insurers and employers. GINA prohibits health insurers from using a person's genetic information to determine eligibility, premiums or rates for both group and individual plans. GINA added to strong legal protections that were already in place on both the state and federal level.
Click here for further information on GINA.