Biomarker Testing for Lung Cancer: Why It’s Important

Medically Reviewed By William C. Lloyd III, MD, FACS
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If you’ve been diagnosed with lung cancer, you’ll undergo testing to learn more about your individual case. For example, imaging studies, such as a CT scan or MRI, can show if your cancer has spread beyond your lungs to other parts of your body. This can help determine what type of treatment is appropriate, such as surgery, radiation, or chemotherapy.

Your doctor may also suggest biomarker testing. This testing looks at your cancer cell DNA for mutations (changes) in genes or the presence of certain proteins that are helping your cancer grow and spread. It can identify if you are a good candidate for additional lung cancer therapies. Biomarker testing can be performed at any stage of lung cancer, but it may be particularly useful after a diagnosis of stage 4 lung cancer, which has been historically challenging to treat.

How does biomarker testing help with treating stage 4 lung cancer?

Biomarker testing is important to determine eligibility for a cancer treatment known as targeted therapy. As we’ve learned about the mutations occurring in cancer cells that allow them to grow out of control, drugs have been developed to “target” and block those changes. Targeted therapy can damage or kill cancer cells, while leaving normal, healthy cells unharmed, unlike traditional chemotherapy.

Several mutations associated with lung cancer have approved targeted therapies. Biomarker testing can tell if you have one of these mutations, such as:

  • Epidermal growth factor receptor (EGFR) mutation
  • Anaplastic lymphoma kinase (ALK) rearrangement
  • NTRK fusion
  • ROS1 rearrangement
  • BRAF V600E mutation

For example, if you have stage 4 lung cancer and are found to have an ALK rearrangement, you may be prescribed a type of targeted therapy called a tyrosine kinase inhibitor (TKI). This drug blocks the signal that tells cancer cells to divide. But if you have an NTRK fusion, you may be treated with a different targeted therapy, such as entrectinib (Rozlytrek) or larotrectinib (Vitrakvi), to disrupt your cancer’s growth. And if you have an EGFR mutation, your doctor may turn to a targeted therapy like amivantamab-vmjw (Rybrevant) to block rapid cancer cell proliferation.

Biomarker testing can also be used to predict your response to lung cancer treatment known as immunotherapy. Immunotherapy boosts your own immune system to help fight cancer; some forms of targeted therapy are also considered immunotherapy. Your cancer cells may be tested for levels of a protein called programmed death-ligand 1 (PD-L1). High levels of PD-L1 can indicate that your cancer is more likely to respond well to a type of immunotherapy called an immune checkpoint inhibitor.  If your cancer isn’t found to have a biomarker for an approved targeted therapy but has high levels of PD-L1, your doctor may suggest an immune checkpoint inhibitor as your first line of treatment.

How is biomarker testing for lung cancer done?

Biomarker testing requires a small sample of cancer cells to be sent to a lab. If you’re having surgery or a biopsy, that sample will come directly from your tumor. A blood sample may be analyzed to check for circulating biomarkers.

Not all tests screen for the same biomarkers. Some may only look for a particular mutation while others may provide more comprehensive biomarker testing, checking for a wide range of genetic changes seen with lung cancer. Ask your doctor about which biomarker tests will be (or have been) used to examine your cancer and how the results will impact your treatment options. Keep in mind, not all biomarkers have approved treatments, but clinical trials and future research may find effective therapies in the future.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Sep 30
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