October is National Breast Cancer Awareness Month. It’s important to familiarize yourself with your personal risk for the disease. About one in eight women will develop breast cancer over the course of their lifetime. If caught early, breast cancer can be treated, and patients can live full, fruitful lives.
Breast cancer is a type of cancer that can be passed down from generation to generation. If you’ve had a first-degree relative (sister, mother, daughter) diagnosed with breast cancer, your risk for developing the disease is higher than the average population. The more relatives you have with breast cancer, the higher your risk.
Another way to further understand your risk for breast cancer is through genetic testing.
Genetic testing for breast cancer can determine a person’s risk for having inherited a genetic mutation associated with risk for cancer, or germline mutations. Heritable cancers, like some forms of breast cancer, are related to germline mutations that can be transmitted from parent to child.
Not all cancers are transmissible from parent to child. Genetic testing cannot determine an individual’s risk for somatic mutations, or mutations that are often caused by environmental factors.
Below is a step-by-step guide you can use to navigate through your personal genetic testing journey.
1. Learn Your Family History
If you are interested in genetic testing, first look at your family history.
Look at both sides of your family – men can pass breast-cancer-causing mutations, too. While rare, breast cancer can develop in men. If you have a male family member who had breast cancer, you should get tested. Similarly, you should ask male family members if there is a history of prostate, pancreatic or colon cancer. A family history of these cancers may put you at an elevated risk of breast cancer. Those who have a biological family member who was diagnosed with any type of cancer younger than age 50 should also consider genetic counseling. This may indicate there are germline mutations in your family, leaving you at an increased risk.
If you had cancer previously, you may want to consider genetic counseling. Individuals who have already had cancer are at an increased risk for other types of cancer, including breast cancer.
All humans have tumor suppressor genes (BRCA genes) on our seventeenth chromosome. When functioning properly, BRCA genes catch mistakes in genetic code that can lead to cancer. Some people are born with a mutation on the BRCA genes. Women who have a BRCA1 or BRCA2 genetic mutation are at an increased risk of breast, ovarian and pancreatic cancers. Men who have a BRCA1 or BRCA2 genetic mutation are at an increased risk of prostate, pancreatic and breast cancers.
2. Determine Who Should Be Tested
To have the most accurate results, carefully select who should be tested. The best candidate is a biological relative (ideally someone like a mother or grandmother) who had or currently has breast cancer. A genetic test will help determine if that individual carries germline mutations. If they do, it is very likely the cancers in your family are being caused by this mutated gene. You may also want to consider genetic testing to further confirm the presence of a mutated gene.
If you also test positive for this mutation, you are at an elevated risk. If a mutated gene is not present, your risk decreases. If that individual is unable to get tested, a genetic counselor will help you determine who is the best candidate.
Once a person has been found to have an abnormal gene, you should proceed by testing the relative most closely related to her (or him). If that next relative does not have it, she or he could not have passed it on to children.
3. Contact a Genetic Counselor
If it makes sense to continue pursuing genetic testing, you should connect with a genetic counselor. A genetic counselor will be able to set up an appointment for testing and help explain the results. A counselor will also be able to recommend next steps once your results are analyzed. Once you’ve consulted a counselor, they will sign you up for a test that best matches your needs.
4. Take the Test
All genetic tests require an individual’s DNA. For a genetic test, the DNA can be extracted in two ways: a saliva sample or a blood sample. In most cases, you will be sent to a lab for bloodwork. The blood is then sent to a genetics laboratory. Geneticists will read the “spelling” of your genetic code to determine if there are mutations present.
There is no single gene that causes breast cancer. That is why for the past decade, panel tests that screen over 30 genes have become the norm. Geneticists always look at the BRCA1 and BRCA2 genes, as they are the genes most likely to carry mutations that lead to breast cancer.
5. Understand Your Results
It will likely take a few weeks for your results to come in. Once they become available, your genetic counselor will walk you through the results and answer questions.
If your results come back positive for abnormal mutations, you are at an increased risk of developing breast cancer. You should share this information with your biological family because they may also want to consider genetic testing to assess their risk. If your results come back negative for abnormal mutations, you do not have an enhanced risk. If your genetic counselor says you have “variants of unknown significance,” this means there is a portion of the gene that looks different from the way it’s normally expected to look. Researchers haven’t yet confirmed whether this variant is a risk factor for cancer. Most geneticists consider this to be a “negative” test.
You may wish to bring someone with you when you get your results. If you are told you have a genetic mutation, having someone who cares about you at your side can be very reassuring. It may also be helpful to have another person available to listen and help remember and record what was said.
6. Screening Recommendations
Be sure to talk with your doctor about all the results you receive. They will help determine the best course of action. Generally, if your results come back positive, you should talk to your primary care provider or OB-GYN to schedule a mammogram and determine a schedule for regular breast cancer screening. In some cases, you may want to discuss whether a preventive mastectomy is an appropriate consideration. If your results came back negative, a genetic counselor may still suggest modifications to the normal breast cancer screening guidelines.