How To Test For Breast Cancer Gene

What Do The Test Results Mean

Some gene expression testing can help predict which women will most likely benefit from chemotherapy after breast surgery. Hormone therapy is a standard treatment for hormone receptor-positive breast cancers, but its not always clear when to use chemotherapy. These tests can help guide that decision. Still, these tests cannot tell any one woman for certain if her cancer will come back with or without chemotherapy.

These tests continue to be studied in large clinical trials to better understand how and when to best use them. In the meantime, ask your doctor if these tests might be useful for you.

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Cardoso F, van’t Veer LJ, Bogaerts J, Slaets L, Viale G, Delaloge S et al. 70-Gene Signature as an Aid to Treatment Decisions in Early-Stage Breast Cancer. N Engl J Med. 2016 375:717-29.

Gnant M, Filipits M, Dubsky P, et al. Predicting risk for late metastasis: The PAM50 risk of recurrence score after 5 years of endocrine therapy in postmenopausal women with HR+ early breast cancer: A study on 1,478 patients for the ABCSG-8 trial. Ann Oncol. 2013 24: iii29-iii37.

Wallden B, Storhoff J, Nielsen T, et al. Development and verification of the PAM50-based Prosigna breast cancer gene signature assay. BMC Med Genomics. 2015 8:54.

What Are My Options If I Have A ‘cancer Gene’

Women in high-risk categories and those who have the genes linked with breast cancer should consider starting regular breast cancer screening at age 25, or 10 years earlier than the age of the youngest relative with breast cancer at the time of their diagnosis.

Get to know how your breasts look and feel. If you notice any changes, see your doctor right away. And talk with your doctor about blood tests, pelvic exams, and transvaginal ultrasound to look for ovarian cancer.

Some women choose to have a preventive mastectomy to lower their chances of breast cancer. Itâs also possible to have your ovaries and fallopian tubes taken out. This doesnât get rid of all risk, but it does significantly lower it.

Another approach includes using anti-estrogen drugs:

• Tamoxifen, useful in premenopausal and post-menopausal women
• Raloxifene , used to treat osteoporosis useful only in post-menopausal women
• Exemestane , an aromatase inhibitor useful only in post-menopausal women

What Do The Results Mean

If HER2 protein levels are higher than normal or extra copies of the HER2 gene are found, it probably means you have HER2-positive cancer. If your results show normal amounts of HER2 protein or the normal number HER2 genes, you probably have HER2-negative cancer.

If your results were not clearly positive or negative, you will probably get retested, either using a different tumor sample or using a different testing method. Most often, IHC is done first, followed by FISH . IHC testing is less expensive and provides faster results than FISH. But most breast specialists think FISH testing is more accurate.

Treatments for HER2-positive breast cancer can substantially shrink cancerous tumors, with very few side effects. These treatments are not effective in HER2-negative cancers.

If you are being treated for HER2-positive cancer, normal results may mean you are responding to treatment. Results that show higher than normal amounts may mean your treatment is not working, or that cancer has come back after treatment.

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What Are The Genetic Mutations Linked To Breast Cancer

Mutations of genes are like spelling errors in the genetic code of a gene. Those who have a gene mutation may be at higher than average risk for developing certain cancers. A genetic mutation that increases the risk of breast cancer is present in some families.

BRCA 1& 2

BRCA1 and BRCA2 are the most common genetic mutations that cause breast cancer. These are short for breast cancer susceptibility gene 1 and breast cancer susceptibility gene 2. The BRCA1 and BRCA2 genes are found in every person.

The BRCA1 and BRCA2 genes are responsible for the repair of certain types of DNA errors that may happen each time a human cell makes a copy of itself. If the gene does not have a mutation, the BRCA1 and BRCA2 genes help ensure the stability of a cell’s genetic material, or DNA, and help stop uncontrolled cell growth.

Mutations of BRCA1 and BRCA2 have been linked to an increased risk for multiple types of cancer, most notably breast and ovarian cancer. Having an inherited mutation in BRCA1 or BRCA2 does not mean a person is guaranteed to develop cancer, but the chances are much higher than for someone who does not have a BRCA1 or BRCA2 mutation. People who inherit a harmful mutation in BRCA1 or BRCA2 have a lifetime risk of developing breast cancer of 50-80%, compared to 13% for an average person without the mutation.

Other Genes Linked to Breast Cancer

People can inherit these mutations from their parents, or mutations can happen during a persons lifetime.

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 1 in 400 people have a harmful BRCA variation.

About 55 to 72 percent 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 Is Genetic Testing

Genetic testing looks for specific inherited changes in a persons genes. Genetic variants can have harmful, beneficial, neutral , or unknown or uncertain effects on the risk of developing diseases. Harmful variants in some genes are known to be associated with an increased risk of developing cancer. These inherited variants are thought to contribute to about 5 to 10% of all cancers.

Cancer can sometimes appear to run in families even if it is not caused by an inherited variant. For example, a shared environment or lifestyle, such as tobacco use, can cause similar cancers to develop among family members. However, certain patterns that are seen in members of a familysuch as the types of cancer that develop, other non-cancer conditions that are seen, and the ages at which cancer typically developsmay suggest the presence of an inherited susceptibility to cancer.

Genes involved in many of the known inherited cancer susceptibility syndromes have been identified. Testing whether someone carries a harmful variant in one of these genes can confirm whether a condition is, indeed, the result of an inherited syndrome. Genetic testing is also done to determine whether family members who have not developed a cancer have inherited the same variant as a family member who is known to carry a harmful variant.

Are Harmful Variants In Brca1 And Brca2 More Common In Certain Racial/ethnic Populations Than Others

Yes. The likelihood of carrying an inherited mutation in BRCA1 or BRCA2 varies across specific population groups. While the prevalence in the general population is about 0.2%0.3% , about 2.0% of people of Ashkenazi Jewish descent carry a harmful variant in one of these two genes and the variants are usually one of three specific variants, called founder mutations. Other populations, such as Norwegian, Dutch, and Icelandic peoples, also have founder mutations .

Different racial/ethnic and geographic populations also tend to carry different variants in these genes. For instance, African Americans have BRCA1 variants that are not seen in other racial/ethnic groups in the United States . Most people of Ashkenazi Jewish descent in the United States who carry a BRCA variant have one of three specific variants . In the Icelandic population, a different variant in BRCA1 is common among those who inherit a mutation in BRCA1.

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What If I Dont Have A Strong Family History

After looking at your family history, the genetic doctor might tell you that its unlikely that you have an inherited faulty gene. In this case, your risk of cancer is the same as other members of the population.

In certain situations, the genetic counsellor might suggest you have regular screening. This is more likely if members of your family have breast or bowel cancer.

You can find out about this in our information about:

What To Think About

Genetic counselling before and after a BRCA test can help you understand the benefits, risks, and possible outcomes of testing.

• To find doctors who do gene tests and counselling, contact your local chapter of the Canadian Cancer Society at www.cancer.ca.
• To find a genetic counsellor near you, contact the contact the Canadian Association of Genetic Counsellors at www.cagc-accg.ca.

• Breast Cancer Risk: Should I Have a BRCA Gene Test?

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How Testing Is Done

Genetic testing can be done on samples of blood or saliva, or from a swab of the inside of a cheek. The samples are sent to a lab for testing.

There are many different possible mutations in the BRCA genes. Testing can be done to look for one specific mutation, or more extensive testing can be done to look for many different BRCA mutations. The approach to testing depends on the situation. For example, if someone is being tested because they have a family member with a known BRCA mutation, testing might focus only on looking for that specific mutation. In people of Ashkenazi Jewish descent, testing might focus on the specific BRCA mutations that are most common in this group of people. But if theres no reason to suspect a specific gene change, testing will likely look for many different mutations.

Talking With Your Health Care Provider

If you have questions about BRCA1, BRCA2 or other high-risk inherited gene mutations or are considering genetic testing, talk with your health care provider.

Your health care provider can help you understand your breast cancer risk and can refer you to a genetic counselor if needed.

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Variant Of Uncertain Significance

A VUS test result is not conclusive. However, most of the time, minor changes in a gene turn out to be normal variants. Most VUS results do not impact the genes ability to work, meaning they dont increase the risk of breast cancer. VUS results are usually treated similar to negative results.

VUS results are much more common with expanded panel testing than with BRCA1/2 genetic testing. Panel testing looks at many genes . With more genes in the test, its more likely youll get a VUS.

Over time, the lab may clarify the meaning of the VUS and send an updated test report to the health care provider who ordered the test. You should be notified if the VUS gets updated.

You can also check with the health care provider who ordered the test every 1-2 years to see if there is any new information about the VUS. While this may seem like a long time to wait, the information isnt likely to change very often.

A VUS test result can be confusing. If you have any questions about a VUS result, meet with a genetic counselor to go over the results.

Can Children Have A Cancer Gene Test

Children under the age of 18 cannot usually be tested. This is because anyone having a genetic test needs to be old enough to make their own choice about whether to have the test or not. They also need to be able to understand the possible benefits and risks that having the test might have on them and their family members.

The exceptions to this are tests for genes that can cause cancer at a young age and for which there is screening that works well. These include:

• familial adenomatous polyposis

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Genetic Counseling And Testing For Breast Cancer Risk

Some women inherit changes in certain genes that increases their risk of breast cancer . Genetic testing can be done to look for mutations in some of these genes. While testing can be helpful in some cases, not every woman needs to be tested, and the pros and cons need to be considered carefully.

When it comes to breast cancer risk, the most important inherited gene changes are in the BRCA1 and BRCA2 genes. Women with one of these gene changes are said to have Hereditary Breast and Ovarian Cancer syndrome.

• Women with a BRCA gene change have a greatly increased risk of getting breast cancer, as well as an increased risk of ovarian cancer, pancreatic cancer, and possibly some other cancers.
• Men with a BRCA gene change are at increased risk of breast cancer , prostate cancer, pancreatic cancer, and possibly some other cancers.

If you have a family history of breast cancer, you have a higher risk of getting breast cancer yourself. Most women with a family history of breast cancer do not have an inherited gene change that greatly affects their risk. Still, an inherited gene change is more likely in women with a strong family history of breast cancer, especially if the family history also includes certain other cancers, such as ovarian, pancreatic, or prostate cancer. The risk of having an inherited syndrome is also affected by:

• The closeness of affected family members
• The number of family members affected
• The age when your relatives were diagnosed

How Is Genetic Testing Done

Genetic tests are usually requested by a persons genetic counselor, doctor, or other health care provider who has reviewed the individuals person and family history. The genetic test options from which a health professional may select include those that look at a single gene and those that look for harmful variants in multiple genes at the same time. Tests of the latter type are called multigene tests.

Testing is done on a small sample of bodily fluid or tissueusually blood, but sometimes saliva, cells from inside the cheek, or skin cells. The sample is then sent to a laboratory that specializes in genetic testing. The laboratory returns the test results to the doctor or genetic counselor who requested the test. It usually takes several weeks or longer to get the test results.

Health insurance typically covers genetic counseling and many genetic tests, if they are considered medically necessary. A person considering genetic testing should discuss costs and health insurance coverage with their doctor and insurance company before being tested.

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Breast Cancer Risk Reduction Guidelines For People With High

If you have a BRCA1/2 inherited gene mutation, there are options to help lower your risk. Discuss these options with your health care provider.

Women with certain other high-risk gene mutations may also consider risk-lowering drugs or preventive surgery to lower their risk of breast cancer. However, risk reduction guidelines for women with other high-risk gene mutations are less clear than those for women with BRCA1/2 mutations. As more is learned about these mutations, guidelines can be more personalized.

Whether or not you have a gene mutation related to breast cancer, there are things you can do to help lower your risk.

• Prophylactic oophorectomy

If you have a BRCA1/2 inherited gene mutation, talk with your health care provider about the pros and cons of these options.

There are risk reduction guidelines for women with some of the other high-risk gene mutations. However, these guidelines may be less clear than those for women with BRCA1/2 mutations. As more is learned about these mutations, guidelines can be more personalized.

If you have a high-risk gene mutation, talk with your health care provider about whether a risk-lowering drug or preventive surgery may be an option for you.

Take your time. Dont feel you need to rush to make a decision.

Learn more about options for women at high risk.

Variant Of Uncertain Significance Result

Getting a result of a variant of uncertain significance can be confusing and frustrating.

With BRCA1/2 testing, most VUS results are later found to be benign variants . However, theres a small chance the VUS will turn out to be a gene mutation that increases breast cancer risk.

With expanded panel testing, youre more likely to get a VUS result because more genes are being tested.

Not knowing whether the VUS helps explain your personal or family history of cancer may add to the stress of an already trying process.

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