3 Things You Should Know About Breast Cancer Genetic Risk

According to the National Institutes of Health, 5% to 10% of breast cancer cases are hereditary. A breast cancer diagnosis can raise questions about more than treatment, including whether you or your family members are at an increased risk because of genetics.

Christine Laronga, MD

Misconceptions about inherited risk are common, from assuming breast cancer always runs in families to believing a negative genetic test means you have nothing to worry about. Understanding what genetic risk really means can help people make informed decisions about screening, genetic testing and prevention.

Christine Laronga, MD, a surgical oncologist in the Breast Oncology Department at Moffitt Cancer Center, explains what you need to know about genetic risk.  

True or false: If breast cancer doesn’t run in my family, I’m not at risk.

This is false. The facts are that about 90% of breast cancer does not have a known cause, meaning it does not have a genetic link. There are also some families that are genetically negative that are producers of breast cancer. But again, it doesn’t mean if there isn’t breast cancer in your family that you’re not at risk. The top two risk factors for breast cancer are being female and getting older, meaning an 80-year-old woman has a higher risk of breast cancer than a 30-year-old.

True or false: If I have a BRCA mutation, I should get a preventive mastectomy.

This depends on the individual. Having a BRCA1 or 2 mutation does place you at an increased lifetime risk of making breast cancer. There is no doubt about that, but neither gene is a 100% guarantee that you would make breast cancer, and therefore, it’s all about deciding your fear of the future cancer versus the impact of removing breasts on the quality of life, which is not insignificant. It is a personal decision, and therefore, if you do have a BRCA mutation, I recommend meeting with a provider so that you can discern the risks and benefits of a preventive mastectomy and learn what other options there are for risk reduction that don’t involve surgery.

True or false: I should know my family’s cancer history on both sides.

This is 100% true. Every parent has a 50/50 shot of sharing a gene they may possess with their child, whether it be a male or a female child. When I’m doing a risk assessment, I always ask about the father’s side of the family because often patients don’t tell you that part of the story. You should know the history of both sides of your family to best assess your risk.

BRCA1 and 2 are the most common hereditary breast cancer genes. So, when we think about whether or not we should get genetic testing, I strongly encourage that a woman meet with a certified genetic counselor to help decide what type of genes you would need to be tested for based on your family’s history.

Not all genes confer the same risk of future development of breast cancer. For example, the BRCA genes have one of the highest risks of future cancer, but others have lower risk. The other really important thing about genes is that not every error inside a gene has the same risk of making breast cancer. In fact, there are some errors in some genes that are so common they don’t increase the risk for breast cancer. So, it’s important to see a specialist if you get diagnosed with a genetic mutation to make sure that you’re not falsely going after preventive surgery that you don’t need because your risk actually isn’t elevated. I always say increase your awareness and get informed for your own safety for the future.