How It Is Done
The health professional taking a sample of your blood will:
- Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
- Clean the needle site with alcohol.
- Put the needle into the vein. More than one needle stick may be needed.
- Attach a tube to the needle to fill it with blood.
- Remove the band from your arm when enough blood is collected.
- Put a gauze pad or cotton ball over the needle site as the needle is removed.
- Put pressure on the site and then put on a bandage.
Talk With Your Health Care Provider Or A Genetic Counselor
The process of genetic testing is complex. Its best to meet with a genetic counselor or a trained health care provider to make decisions about testing. They can help you choose a test that meets your needs.
Your health care provider or a genetic counselor can help you correctly interpret the test results. If the testing was not done in a certified lab, your health care provider can arrange a clinical genetic test to confirm the results.
If clinical genetic testing finds a gene mutation related to breast cancer, your health care provider or a genetic counselor can help you make informed decisions about breast cancer screening and any risk-lowering options that may be right for you.
Learn about genetic test results.
How Does Genetic Testing For Breast Cancer Work
Genetic testing for breast cancer risk typically uses a sample of blood, saliva, or cells from the inside of your cheek. After the sample is collected, its sent to a lab specializing in genetic testing to be analyzed.
Several gene variations that increase breast cancer risk have been found. The most important are those in the BRCA1 and BRCA2 genes. According to the National Cancer Institute, about people have a harmful BRCA variation.
About of females with harmful BRCA1 and 45 to 69 percent of females with harmful BRCA2 variations will develop breast cancer by age 80. Their risk of getting breast cancer in the other breast is also higher.
Other gene variants that may raise breast cancer risk include:
- PALB2
- PTEN
- TP53
Gene variations that can be detected may vary by test. For example, some tests may only cover the most common variations, while others may be more extensive.
Once your sample is submitted, youll receive your results in 2 to 4 weeks. A healthcare professional or genetic counselor will contact you and discuss your results.
Results you can receive include:
- Positive: A known gene variation that increases your risk of breast cancer was detected.
- Negative: A known gene variation that raises your risk of breast cancer was not detected.
- Variant of unknown significance: A variant has been found in a gene, such as BRCA1 or BRCA2, but its impact on breast cancer risk is currently unknown.
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What Are The Potential Problems With Genetic Testing
Genetic testing is not 100% accurate. If a test is negative, a person still has a chance of getting breast cancer. If the test is positive, there is still a 15% to 20% chance of not getting breast cancer.
Continued
Genetic testing is costly, ranging from about $400 to more than $3,000, depending on the type of test. Insurance coverage varies.
The results of genetic tests wont be available for several weeks. The length of time it takes to get results depends on the tests performed and under what circumstances they are done.
Genetic testing is very controversial. Legislation has been enacted to protect people who may have a documented genetic risk of cancer from employment or insurance problems. The best thing you can do is to become involved with an established genetic registry that can counsel people who have a genetic risk for cancer.
Are There Any Risks
The BRCA blood test does not carry any physical risks, but it could have a psychological impact, such as stress or anxiety about the test results. Genetic testing can sometimes be expensive. If a doctor or genetic counselor orders the test, your insurance will likely cover the cost, but this may not be the case for certain health plans.
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Stage : A Full Screen
The first stage involves testing a relative who has had cancer to try to find out if a known altered gene runs in the family.
This will usually be a relative who has had breast or ovarian cancer, but in some cases it might be a relative who has had prostate cancer.
Altered genes can be difficult to find. Theres a better chance of finding an altered gene in someone who has already been diagnosed with breast or ovarian cancer.
A blood sample is taken and sent to a laboratory to be tested for known altered genes.
If you have had breast or ovarian cancer, you can have the test yourself.
In rare circumstances, if no relatives are available for testing and you have not had cancer, you may be able to have the test yourself. Your genetics team will tell you if this is an option.
The results
Results are usually available within one to three months. Your genetics team will let you know how the results will be given to you. You may have a clinic appointment, a telephone call or have the results sent in the post.
There are three possible outcomes.
A positive result
If an altered gene is found , this confirms your chances of developing breast cancer are higher than the general population.
Your genetics team will know which gene runs in your family. They can then search for the alteration more easily in other family members, who can be tested to see if they also carry it .
A negative result
A negative result means a known altered gene was not found.
A variant of unknown significance
How Is It Used
Standard BRCA1 and BRCA2 tests are used to detect mutations that are known to increase the risk of breast and ovarian cancer development. If a BRCA1 or BRCA2 mutation has been identified in a family member with breast and/or ovarian cancer, then that specific mutation can be tested in other family members to assess their risk. Specific BRCA1 and BRCA2 mutations are associated with some ethnic groups, such as those of Ashkenazi Jewish descent, and can be used to evaluate the risk of individuals in this group.
Only about 0.2% of the U.S. population carries a BRCA1 or BRCA2 mutation. Because of this, genetic testing is not recommended for the general population.
BRCA1 and BRCA2 mutation testing should be considered for individuals with a personal or family history that suggests the presence of a harmful BRCA1/BRCA2 mutation. There are a variety of screening tools to help assess the risk of having a BRCA mutation. Some of the risk factors include:
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How Are The Brca1 And Brca2 Genes Inherited
All our genes come in pairs we inherit one of the pair from our mother and the other from our father. When we have children, we randomly pass on one of each pair. If a person has an alteration in a BRCA1 or BRCA2 gene, each of their children has a 50:50 or one in two chance of inheriting it. An alteration can be inherited from either parent.
If a person has not inherited a BRCA1 or BRCA2 alteration, they cannot pass it on to their children.
Less Common Altered Genes
Women with an altered PALB2 gene have a 4463% risk of breast cancer.
TP53
Women with an altered TP53 gene have an up to 85% risk of breast cancer.
The lifetime risk for a person with an altered TP53 gene to develop any type of cancer is 90%.
CHEK2
Women with an altered CHEK2 gene have a moderate risk of developing breast cancer.
Moderate risk is higher than the general population. However, its still more likely they will not get breast cancer.
ATM
Women with an altered ATM gene have a moderate risk of developing breast cancer.
Moderate risk is higher than the general population. However, its still more likely they will not get breast cancer.
Other genes
Some genetic conditions caused by rare altered genes are also associated with breast cancer.
These include:
- Peutz-Jegher syndrome
- Cowden syndrome/PTEN hamartoma tumour syndrome
- Hereditary diffuse gastric cancer syndrome gene)
- Neurofibromatosis type 1
If one of these runs in your family, your genetics team will talk to you about your risk of breast cancer.
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Why Are Tumor Marker Tests Used
Along with other tests, tumor marker tests can help doctors diagnose cancer and recommend a treatment plan for an individual. Why, when, and how often these tests are done varies greatly from person to person. Rarely, they are used to help screen for a particular type of cancer in people with a high risk of the disease before they have signs and symptoms. But doctors mainly use tumor marker tests to:
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Figure out how well a treatment is working
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Predict a persons chance of recovery
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Predict how likely it is a cancer will come back after treatment and find it if it does
Screening For Other Cancers
People with a BRCA1 or BRCA2 mutation are not usually offered screening for other cancers. This is because:
- the risk of other cancer types linked to BRCA1 or BRCA2 mutations is usually much lower than for breast cancer in women
- regular screening tests cannot prevent these cancers
- there is no clear evidence that screening tests for these cancers are good at finding cancer early when it is more treatable.
Sometimes screening for other cancer types is offered as part of a research trial. Taking part in a research trial is completely up to you. Your doctor or nurse can explain the possible risks and benefits of taking part.
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What Your Breast Cancer Genetic Tests Results Mean
Having a positive genetic test result doesnt mean youll get cancer. It means you have a higher risk of getting breast cancer than people without the mutation.
- Women without breast cancer gene mutations have a 12% lifetime risk of breast cancer.
- Women with a BRCA mutation have up to an 80% lifetime risk of breast cancer.
- Women with the PTEN mutation have an 85% lifetime risk.
- Men with the BRCA2 mutation have about an 8% lifetime risk, 80 times greater than males without the mutation.
Even if you get tested and get a negative result, dont skip mammograms or other health screenings, and continue to follow the American Cancer Societys guidelines.
Most cases of breast cancer arent hereditary, says Dr. Eng. A negative result means you dont have the known gene mutations for breast cancer. But you can still get breast cancer.
Can I Do Genetic Testing At Home
Some at-home genetic tests can help you determine breast cancer risk. These tests typically involve providing a sample of saliva or cheek cells and sending the sample by mail to be tested.
Its recommended that you seek genetic testing from a healthcare professional rather than using an at-home test for the following reasons:
- an incomplete result: At-home tests may not cover all known variants of a gene, such as BRCA1 or BRCA2. Because of this, a negative result can be misleading.
- unnecessary alarm: At-home tests may detect common genetic variants that are only associated with a slight increase in breast cancer risk, meaning that a positive result may cause unnecessary alarm.
- genetic counseling: With genetic testing through a healthcare professional, youll often also have access to genetic counseling both before and after you receive your result. This can help you better understand your result in the context of your overall health.
- privacy: Your privacy may not be ensured when you use an at-home test. If you do choose to use one, carefully review a companys disclosure policy beforehand.
Getting genetic testing for breast cancer risk has several benefits. But there are some risks involved as well.
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What Suggests A Possible Brca Mutation
Mutations in the BRCA genes cause particular patterns of cancer down the generations. The estimated frequency of BRCA1 or BRCA2 gene mutation carriers in the general population is around one in 1,000 people. The frequency in specific population groups is higher, for example in people of Ashkenazi Jewish descent, the rate of BRCA gene mutation carriers is one per 50 to 100 people.
Features suggestive of a potential BRCA mutation within a family are, multiple cases of breast cancer on the same side of the family, often with early onset such as age less than forty, ovarian cancer in a family with a history of breast or ovarian cancer, breast and ovarian cancer in the same woman, cancer in both breasts, Ashkenazi Jewish heritage, and male breast cancer.
How To Organise Testing
Technical Information
Testing targets specific gene mutations and does not detect mutations that are outside of the targeted area. Testing does not completely sequence every exon of each one of the cancer genes. The limit of detection is 5% at 500X coverage and 10% at 200X coverage. The limit of detection for sequencing is ~1%. For medical practitioners seeking further technical information regarding the assay, please contact Genomics For Life.
References
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If I Have A Positive Result Should I Tell My Family Members
Positive test results may have implications for other family members. When one member of a family is tested for pathogenic BRCA mutations, issues often arise about how to share this information with other family members. It may be helpful to seek advice from a genetic counselor about how to communicate results with other family members.
Can I Have A Test To See If The Cancers In My Family Are Due To An Alteration In Either Brca1 Or Brca2
Possibly. A persons genes can be examined from a blood sample. At present, however, it is usually only offered to families with a strong history of breast, ovarian or prostate cancer. This is because only a small number of people with these cancers will have a BRCA1 or 2 gene alteration and because the test results can be difficult to interpret. Under current guidelines there needs to be at least a 10% chance of finding a BRCA1 or 2 gene alteration for testing to be offered.
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British Columbia Specific Information
Breast cancer is the most common type of cancer in women in British Columbia. Breast cancer can occur in men as well, but it is not as common. Tests and treatments for breast cancer vary from person to person, and are based on individual circumstances. Certain factors such as your age, family history, or a previous breast cancer diagnosis may increase your risk of developing breast cancer. For information about your specific risk factors, speak with your health care provider.
A number of screening methods, including mammograms in women, can help find and diagnose breast cancer. The decision to have a mammogram or use any other screening method may be a difficult decision for some women. While screening for breast cancer is often recommended, it is not mandatory. Speak with your health care provider for information regarding how to get screened, the facts and myths about screening tests, how to maintain your breast health, and to get help making an informed decision.
For more information about breast cancer and breast cancer screening, visit:
If you have questions about breast cancer or medications, speak with your health care provider or call 8-1-1 to speak with a registered nurse or pharmacist. Our nurses are available anytime, every day of the year, and our pharmacists are available every night from 5:00 p.m. to 9:00 a.m.
Are Brca1 Or 2 The Only Genes That Can Cause Inherited Breast Cancer
No. There are other genes that increase the chance of developing breast and/or ovarian cancer. There is a panel of breast cancer genes that can be tested if there is a strong enough family history of breast cancer or a panel of ovarian cancer genes if there is a strong enough family history of ovarian cancer. The threshold for panel testing is higher than that for testing the BRCA1 and 2 genes only. Research is continually updating our knowledge in this area. For more information about these gene panels ask your clinician.
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