Our genetic code is what allows us to pass along hereditary information from generation to generation. We all have one and they’re all unique. Sometimes, unfortunately, changes occur in that gene code called mutations, and those mutations can affect our risk for certain diseases. Including breast cancer.
During Breast Cancer Awareness Month, we’re sharing as much information as we can about breast cancer, and breast cancer genetics is an important and often misunderstood aspect of the disease. The National Breast Cancer Foundation has a great tutorial on the subject, so we wanted to share it with you here.
BRCA: The Breast Cancer Gene
The name “BRCA” is an abbreviation for “BReast CAncer gene.” BRCA1 and BRCA2 are two different genes that have been found to impact a person’s chances of developing breast cancer.
Every human has both the BRCA1 and BRCA2 genes. Despite what their names might suggest, BRCA genes do not cause breast cancer. In fact, these genes normally play a big role in preventing breast cancer. They help repair DNA breaks that can lead to cancer and the uncontrolled growth of tumors. Because of this, the BRCA genes are known as tumor suppressor genes.
However, in some people these tumor suppression genes do not work properly. When a gene becomes altered or broken, it doesn’t function correctly. This is called a gene mutation.
BRCA Mutations
A small percentage of people (about one in 400, or 0.25% of the population) carry mutated BRCA1 or BRCA2 genes. A BRCA mutation occurs when the DNA that makes up the gene becomes damaged in some way.
When a BRCA gene is mutated, it may no longer be effective at repairing broken DNA and helping to prevent breast cancer. Because of this, people with a BRCA gene mutation are more likely to develop breast cancer, and more likely to develop cancer at a younger age. The carrier of the mutated gene can also pass a gene mutation down to their children.
BRCA Mutation Risks
It is estimated that one in eight women, or approximately 12%, will be diagnosed with breast cancer in her lifetime. However, women with certain genetic mutations have a higher lifetime risk of the disease. It’s estimated that 55–65% of women with the BRCA1 mutation will develop breast cancer before age 70 and approximately 45% of women with a BRCA2 mutation will do the same.
Women with a BRCA1 or BRCA2 mutation who overcome their breast cancer with treatment appear to have a higher-than-average chance of developing a second cancer. Breast cancer does not spread from one breast to another as they are truly different organs. Having breast cancer in one breast does not actually significantly increase the risk of developing a breast cancer in the other breast. What makes BRCA patients unique is that not only are they at risk for one cancer, they are at risk for a completely different one in the other breast. Cancers related to a BRCA1 mutation are also more likely to be triple negative breast cancer, which can be more aggressive and can be difficult to treat.
While these statistics may be alarming, it’s important to note that less than 10% of women diagnosed with breast cancer have a BRCA mutation. Also, many people who carry these gene mutations never develop breast cancer. And with early detection, the vast majority of breast cancer cases can be successfully treated—and that’s true even for people who have a BRCA1 or BRCA2 mutation.
When To Get Tested For BRCA
While BRCA1 and BRCA2 gene mutations may increase your odds of developing breast cancer, your odds of having either mutation are small. An estimated 0.25% of the general population carries a mutated BRCA gene, or about one out of every 400 people.
For some people, though, the chances of having a BRCA gene mutation are much higher. Genes are inherited, which is why knowing your family history is important when determining breast cancer risks. If one of your parents has a BRCA mutation, you have a 50% chance of inheriting the mutated gene.
Odds can also vary depending on your ethnicity. For example, people of Ashkenazi Jewish descent have a 2.5% chance of inheriting a BRCA mutation, or about 10 times the rate of the general population.
Because the overall odds are so low, most experts recommend that only people with a heightened risk get tested for BRCA mutations. A person could be considered at high risk for BRCA mutations if they have a family history of:
- Breast cancer diagnosed before age 50
- Male breast cancer at any age
- Multiple relatives on the same side of the family with breast cancer
- Multiple breast cancers in the same woman
- Both breast and ovarian cancer in the same woman
- Ashkenazi Jewish heritage
There are also other gene mutations besides BRCA that could increase the risk of breast cancer. As with BRCA1 and BRCA2, testing for other genetic mutations is recommended only if there is suspicion that you are at high risk for that particular gene.
How To Get Genetic Testing
The standard of care for people who are interested in being tested for breast cancer gene mutations start with genetic counseling. A genetic counselor can help determine whether genetic testing would make sense based on your family history and risk factors. Since many genetic tests only look for one specific gene mutation, a counselor can often help determine which mutations to test for.
The genetic test itself simply involves taking a small sample of blood or saliva, which is sent to a lab for analysis. Results can take several weeks and are not always clear-cut. That’s why you should meet with your genetic counselor again after receiving the results. Whether the results are positive, negative, or ambiguous can impact many life decisions, and a counselor can help navigate those decisions.
Early Detection Plans
Knowing if you’re carrying a breast cancer gene mutation can allow you to work with your doctor to create a custom detection plan to increase the chances that your breast cancer is found early. Early detection makes breast cancer far easier to treat. Overall, the five-year relative survival rate for breast cancer detected in the localized stage (there is no sign that the cancer has spread outside of the breast) is 99%.
An early detection plan for someone with a BRCA or other high-risk gene mutation will likely involve more frequent breast cancer screenings starting at a younger age. It may also involve different types of screenings, such as MRI scans. Your doctor can help recommend which screenings you should have, and when you should have them.
Having a genetic predisposition to develop breast cancer doesn’t mean you will. But if your history or heritage suggest you might be at higher risk, talk to your doctor and a genetic counselor about being tested and get advice on interpreting the results. Then, if you need to, put an early detection plan in place. Because when you identify breast cancer early, it’s treatable and beatable.