Your genes affect your breast cancer risk
What are genes, and what do they have to do with cancer?
Genes are instructions, written in DNA, that tell your body how
to make the proteins it needs to function. You inherit your genes from your parents,
who inherited their genes from their parents, and so on. Genes affect everything
about your body, from your eye color and height to your breast cancer risk.
Genes can change over time. These changes are called mutations,
and certain genetic mutations can make cells grow out of control, leading to cancer.
Only about 5% to 10% of cancers are believed to have a genetic component that strongly
affects a person’s risk. But changes in some genes—such as the BRCA1 and BRCA2 genes
for women whose mothers or sisters have had breast cancer—can affect breast and
ovarian cancer risk.
What is genetic testing, and when is it performed?
Genetic tests can show if someone has a certain mutation that will increase the
risk of breast cancer. Not everyone needs to have breast cancer genetic
testing performed. But if certain diseases such as breast cancer run in the family,
genetic testing may be beneficial.
There are a few different types of genetic testing. Predictive gene testing
looks for mutations that may put someone at risk for diseases such as breast cancer.
Carrier testing can help couples find out if they may carry and
possibly pass on a mutation to a child.
In addition, pregnant women can have their unborn children tested for certain conditions.
And newborns may be screened. (Newborn screening is the most common form of genetic
testing.)
Predictive gene testing and breast cancer.
For women who’ve recently been diagnosed with breast cancer, a mutation in the BRCA
genes means at least a 3-times-higher risk of developing cancer in the opposite
breast over the next 10 years, compared to recently diagnosed women without the
mutation.
Women with the BRCA mutations also have a higher risk of developing a second breast
cancer in the same breast, if they have a lumpectomy (surgery to remove the tumor,
leaving as much of the breast in place as possible) versus a mastectomy (surgery
to remove the entire breast).
Genetic testing can also be used to help plan treatment.
Instead of determining a person’s cancer risk, genetic testing can also be used
to find out more about a cancer that’s already present. Genetic testing can give
information on how someone may benefit from certain treatments. Talk to your healthcare
team to see if this testing is right for you.
Who should look into breast cancer genetic testing?
If you have the following family associations with breast cancer, you may want to
consider predictive genetic testing:
- Several first-degree relatives (mother, father, sister, brother) with cancer, particularly
with the same type of cancer
- Family members who developed cancer at a young age
- Family members with rare cancers
- A genetic mutation in the family. You would find this out from a family member who
had genetic testing
A word of caution about genetic testing.
Although genetic testing makes sense for some women with a family background of
cancer, women should consider how knowing that they have a certain genetic
mutation could affect their families, especially their daughters and granddaughters.
Besides being frightening, finding out about a genetic mutation could lead to job
and insurance discrimination. New laws are currently addressing these privacy issues.
But the most important thing to keep in mind when considering genetic testing is
that a negative result is no guarantee. One negative test result does not mean,
definitely, that a woman doesn’t have a specific mutation which could put her at
a higher risk of breast cancer. And if she doesn’t have that mutation, she could
still develop breast cancer. Cancer affects many people who have no strong risk
factors.
In general, no one should undergo genetic testing without talking to a trained,
professional genetic counselor.
What are the symptoms of breast cancer?
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