What is genetic testing?

Genetic testing is the use of medical tests to look for certain mutations (changes) in a persons genes. Many types of genetic tests are used today, and more are being developed.

Genetic testing can be used in many ways, but here well focus on how it is used to look for gene changes that are linked to cancer. (To learn about the role of genes and how mutations can lead to cancer, seeGenes and Cancer.)

Predictive genetic testing is a type of testing used to look for inherited gene mutations that might put a person at higher risk of getting certain kinds of cancer. This type of testing might be suggested for:

Most people (even people with cancer) do not need this type of genetic testing. Its usually done when family history suggests that a cancer may be inherited (see below) or if cancer is diagnosed at an uncommonly young age.

Genetic counseling and testing may be recommended for people who have hadcertain cancers or certain patterns of cancer in their family. If you have any of the following, you might consider talking to a genetic counselor about genetic testing:

If you are concerned about a pattern of cancer in your family, cancer youve had in the past, or other cancer risk factors, you may want to talk to a health care provider about whether genetic counseling and testing might be a good option for you.

You need to know your family history and what kinds of tests are available. For some types of cancer, no known mutations have been linked to an increased risk.

For more information on the types of cancer that may be linked to inherited genes,see Family Cancer Syndromes.

Genetic counseling gives you information that you and your family can use to make decisions about whether to get genetic testing (see below).

Genetic counselors have special training in the field of genetic counseling. Most are board-certified, and some might have a license depending on the rules in their state. Some doctors, advanced practice oncology nurses, social workers, and other health professionals may also provide genetic counseling, although they might have different levels of training in this field. If you are offered genetic counseling, its fair to ask about their training in this area.

Before and after genetic testing, genetic counseling can help you understand what your test results might mean, your risk of developing cancer, and what you can do about this risk. It is your decision to have testing and what steps you take after.

Its important to find out how useful genetic testing might be for you before you do it. Talk to your health care provider and plan on getting genetic counseling before the actual test. This will help you know what to expect. Yourcounselor can also tell you about the risks and benefits of the test, what the results might mean, and what your options are.

Your health care provider can refer you to a genetic counselor in your area, or you can find a list of certified genetic counselors on the website of the National Society of Genetic Counselors.

To learn more, see What Should I Know Before Getting Genetic Testing?

Sometimes after a person has been diagnosed with cancer, the doctor will order tests on a sample of cancer cells to look for certain gene or protein changes. These tests can sometimes give information on a persons outlook (prognosis), and they might also help tell if certain types of treatment may be useful.

These types of tests look for acquired gene changesonlyin the cancer cells. These tests are not the same as the tests used to find out about inherited cancer risk.

For more about this kind of testing and its use in cancer treatment, see Biomarker Tests and Cancer Treatment.

Some tests that look for gene changes can be bought without needing a doctors order. For this type of testing, you purchase a test kit and send a sample of your DNA (often from saliva) to a lab for testing.

If you are considering using a home-based genetic test (also known as a direct-to-consumer genetic test), you need to know what its testing for, what it can (and cant) tell you, and how reliable the test is.

Home-based tests do not provide information on a persons overall risk of developing any type of cancer. Sometimes these tests can sound much more helpful and certain than they have been proven to be. It may sound like the test will provide an answer to your specific health concern, such as your risk of hereditary cancer, but the test may not be able to answer that question completely. For example, a test may look for mutations in a certain gene, but it might not test for all of the possible mutations. So a negative test result, even if accurate, may miss the bigger picture regarding your cancer risk and what you can do to manage it. And you might not be provided with the important context about the test results that a genetic counselor could provide.

Home-based genetic tests should not be used instead ofcancer screeningorgenetic counselingthat may be recommended by a medical professional based on your individual risk for cancer.Always consult with your doctor if you are considering or have questions aboutgenetic testing. Trained genetic counselors can help you know whatto expect from your test results.

Link:
Understanding Genetic Testing for Cancer Risk

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