Many people think that genetic testing for hereditary breast and ovarian cancer is simply to test for BRCA1 and BRCA2 gene mutations. However, since 2013, it has become more commonplace to offer multi-gene tests (also known as gene panels) that include other genes outside of BRCA1 and BRCA2.
Approximately 5-10% of all breast cancer is actually hereditary, but of the hereditary cases, 50% are thought to be linked to BRCA1 and BRCA2. Outside of that, there are many other genes we can do testing for now.
These are the general categories of genes that could be included on a hereditary breast cancer gene panel:
- High-Risk Genes: Associated with 39-87% lifetime risk to develop breast cancer
- Moderate-Risk Genes: Associated with 23-58% lifetime risk to develop breast cancer
- Newly Described Genes: Associated with an increased risk for breast cancer, but may not have well defined risk estimates
High and Moderate-Risk Genes
In regards to the high-risk breast cancer genes, there are clear cut guidelines for screening and prevention available. For the moderate-risk breast cancer genes, there may be some guidelines available, but the guidelines will likely evolve as more information is obtained.
For example, a gene called ATM is associated with a moderate-risk to develop breast cancer, and there are guidelines available to tell us how often to screen a woman’s breasts. ATM is also associated with an increased risk for colorectal cancer, but we do not have enough data that exists on that risk to have a formal guideline tell us how often to screen a patient with colonoscopy yet. Some patients feel comfortable with having moderate-risk genes tested because there are some medical management options available, and there is “something they can do” about their risk.
Newly Described Genes
There are also newly described genes that are being included on breast cancer gene panels, where there is existing data that suggests an association with an increased risk for breast cancer, but not enough data to give a well-defined risk estimate. Because of this, there may not be medical management options available yet, because we are unsure of how much risk is involved.
When a person tests positive for a gene mutation in a newly described gene, medical management recommendations are heavily dependent on what is seen in the family history. Some patients feel that having newly described genes tested is still helpful because the field of genetics is rapidly growing, and they may be able to use this genetic information in the near future, whether it be for themselves or for their children/grandchildren. Other patients are not comfortable having their newly described genes tested, because if something is found, it could cause them anxiety if there is a lot of uncertainty about the gene and/or medical management.
How Genetic Counseling May Help
Because of all of the complexities that exist with hereditary cancer genetic testing these days, genetic counseling is essential for patients to understand:
- The full extent of their options regarding genetic testing
- How genetic testing may or may not change their medical management
- How this could affect their family members and their medical management insurance coverage for genetic testing
- How much uncertainty can come from a genetic test.
If you have questions regarding genetic counseling or genetic testing, please call the ProMedica Cancer Institute’s Cancer Genetics Program at 419-824-5073.
Sarah Adelsperger, MS, LCGC, is a board-certified genetic counselor specializing in cancer. Sarah joined Kelly Morse, MS, LCGC, in the Cancer Genetics Program in May 2015 at ProMedica Cancer Institute–the only program in Northwest Ohio and Southeast Michigan with two licensed and board-certified genetics counselors specializing in cancer genetics.