Lung Cancer Genetic Tests

What are lung cancer genetic tests?

Lung cancer genetic tests look for changes in the genes of cancer cells in your lungs. Your health care provider can use the results of these tests to decide how best to treat lung cancer.

Genes are sections of DNA in your cells that you inherit from your parents. They carry information that controls what you look like and how your body works. They also provide instructions for your cells to make proteins, which your body needs to work correctly.

If your lung cancer cells have a gene change (also called a gene variant or mutation), then they may grow out of control and form cancerous tumors that can spread throughout your body. This is because cells with these gene changes make abnormal versions of that gene's associated protein. Some of these abnormal proteins affect how fast your cells grow and divide to make new cells.

These gene changes are acquired during your lifetime. This means that you did not inherit these gene changes from your parents and that you can't pass them down to your children. Instead, these changes (often called acquired gene changes) form if your cells make a mistake when dividing to make new cells or if your DNA is damaged from exposure to substances that cause cancer.

For lung cancer, some of the most common substances that can damage your DNA include:

• Tobacco smoke
• Radon gas
• Air pollution

There are two main types of lung cancer, small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). NSCLC is more common and more likely to have the gene changes a lung cancer genetic test looks for.

Other names: Lung cancer targeted gene panel

What are they used for?

Providers often use lung cancer genetic testing to see if your lung cancer cells have certain gene changes. They can use the results of these tests to:

• Learn more about your cancer and how it may respond to treatment
• Find out whether a targeted therapy or any other treatment will work for you

Targeted therapy uses medicines or other substances that mainly attack specific cancer cells and cause less harm to normal cells. It may have fewer side effects than chemotherapy or radiation therapy. There are different types of targeted therapies. Each type is designed to work for cancers with specific gene changes. So, lung cancer genetic tests can help your provider find out whether your cancer has a gene change that may be treated with a targeted therapy.

Because there are many types of gene changes that can be involved in NSCLC, your provider may check for several of these changes in one lung cancer genetic test.

Why do I need a lung cancer genetic test?

You may need lung cancer genetic testing if you have been diagnosed with lung cancer and your provider wants to use the results of these tests to decide which type of treatment to use.

You may also need lung cancer genetic testing if your cancer:

• Comes back after treatment
• Stops responding to treatment

This is because cancer cells can change over time. Additional testing can help your provider see if there are any new gene changes that could affect your treatment options.

What happens during a lung cancer genetic test?

Lung cancer genetic testing may be done on a sample of tumor tissue, or, in some cases, a sample of blood.

The procedure to collect a lung tissue sample is called a biopsy. A biopsy is the procedure of removing and examining tissue, cells, or fluids from the body. There are several ways to do a lung biopsy. The type you have depends on where the tumor is located. In general, a biopsy may be done using:

• A hollow needle inserted through your skin. Imaging tests, such as a CT scan, may be used to guide the needle:
  • A fine needle aspiration biopsy uses a very thin needle to remove a sample of cells and/or fluid.
  • A core needle biopsy uses a larger needle to remove a sample.
• Surgery. A surgeon may remove a sample of the tumor (incisional biopsy) or the entire tumor (excisional biopsy).
• Bronchoscopy and bronchoalveolar lavage (BAL). A provider uses a thin, lighted tube with a tiny camera (a bronchoscope) to view images of your airways.
  • The tube is put through your mouth or nose, down your throat, and into your airways.
  • Once the camera is in your airways, a provider will perform a BAL to collect a sample from your lungs.
  • To do this, a saline solution is put through the bronchoscope to wash your airways and capture a fluid sample.

In some cases, your provider may use a blood test to look for certain gene changes. This is because tumor cells shed DNA into your bloodstream. Testing the tumor DNA in your blood is called a “liquid biopsy.” Providers may use this type of test if they are unable to collect a tissue sample using a biopsy.

Will I need to do anything to prepare for the test?

If you are having a blood test, you usually don't need any special preparation.

If you need a biopsy, how you prepare depends on the type of procedure you're having. Your provider will tell you if you need to do anything before the procedure.

If you need a bronchoscopy or a BAL, you may need to fast (not eat or drink) for several hours before your procedure. Your provider will let you know how long not to eat or drink. You may need to stop taking certain medicines before this test, so tell your provider about everything you take. But don't stop taking any medicines unless your provider tells you to.

Are there any risks to the test?

There is very little risk to a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

If you have a biopsy, the risks depend on the type of procedure you have. In general, you may have a little bruising or bleeding at the biopsy site. You may also have some discomfort. Ask your provider about any risks involved with the test you're having.

There is very little risk to having a bronchoscopy or a BAL. Serious complications are rare, but they may include bleeding in the airways, infection, or a pneumothorax (collapse of part of your lung).

What do the results mean?

If your lung cancer cells have a gene change that may respond well to a targeted therapy, your provider may start you on that treatment.

If your results show you don't have a gene change that matches a targeted therapy, your provider may discuss other treatment options. If you were tested for one gene change, other tests may be done to look for other gene changes that have targeted therapies.

Your test results may also show that your lung cancer has a gene change that:

• May prevent a certain therapy from working. This information could spare you from getting treatment that won't help.
• Doesn't provide useful information for choosing a treatment. Researchers don't understand the importance of all the gene changes that are found in cancer.

If you had a liquid biopsy, a negative result doesn't always mean that your tumor doesn't have a gene change that could affect treatment. Your provider may recommend testing tumor tissue if possible to confirm the results of the liquid biopsy.

If you have questions about your results, talk with your provider.

Learn more about laboratory tests, reference ranges, and understanding results.