Biomarker Resource Center
Lung Cancer Biomarkers
Reviewed by XpertPatient Medical Advisory · Updated August 2026 · Primary Source: cancer.gov
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What Is a Biomarker — and Why Does It Matter for Your Treatment?
A biomarker in lung cancer is a gene change found in your tumor. Doctors find these changes by testing a small piece of your tumor tissue.
Think of it like a clue. Your doctor collects clues from your biomarker test results. Those clues help build a picture of your cancer. That picture helps you have a more informed conversation with your care team about next steps.
How a Biomarker Test Works
A biomarker is a signal your cancer leaves behind. Your doctor finds it through a biopsy or blood test, reads your results, and uses them to choose the treatment most likely to work for your specific tumor.
Why Do Biomarkers Matter in Lung Cancer?
If your tumor has a specific gene change, there may be a targeted approach designed to block it. This can work better than standard chemotherapy for some patients. Biomarker testing should happen before treatment begins.
The most important lung cancer biomarkers are EGFR, ALK, KRAS, and PD-L1. Together they help your doctor understand your tumor and which approaches may be most appropriate for your situation.
A good question to ask your doctor: Ask your doctor whether full biomarker testing has been done before treatment starts.
Quick Poll
Have you been biomarker tested?
Knowing your EGFR, ALK, KRAS, and PD-L1 results before treatment is one of the most important steps you can take.
Source: Hess et al., Clinical Lung Cancer, November 2025 · first-line biomarker testing rate in metastatic NSCLC (n=4,528) · www.sciencedirect.com
The Tests Your Doctor May Order
Is there a gene change that a targeted approach can address?
EGFR mutations are found in about 15% of lung cancers. If your tumor has this mutation, your doctor will discuss targeted approaches. Ask your doctor whether EGFR testing has been done and what your result means.
Did two genes join in a way that drives cancer growth?
ALK rearrangements are found in about 5% of lung cancers, more often in younger patients and non-smokers. Ask your doctor whether ALK testing was done and what your result means.
Is there a common driver mutation in your tumor?
KRAS is the most common mutation in lung cancer. Specific KRAS subtypes now have targeted options available. Ask your doctor whether your specific KRAS subtype has been identified.
Can immunotherapy help your immune system fight the cancer?
PD-L1 testing helps your doctor decide whether immunotherapy may be an option. Ask your doctor what your PD-L1 result means for your care.
Has your tumor been tested for all relevant gene changes at once?
Comprehensive genomic profiling tests your tumor for many gene changes in a single test. It can find rare mutations that smaller panels miss. Ask your doctor whether comprehensive profiling has been done.
Sources: National Cancer Institute · LUNGevity Foundation · American Cancer Society
Watch & Learn
Common Questions
Lung Cancer Biomarkers — Your Questions Answered
Do all lung cancer patients need biomarker testing?
Yes. If you have non-small cell lung cancer, full biomarker testing is recommended before any treatment starts. If it has not been done, ask your doctor to order it.
What if my tumor has no targetable mutations?
About 30 to 40% of lung cancers have no currently targetable mutation. Immunotherapy or chemotherapy are the main options. Ask about clinical trials.
What is a liquid biopsy?
A blood test that finds cancer DNA in your bloodstream. Useful when getting a tissue biopsy is hard or to monitor treatment response.
What is comprehensive genomic profiling?
A test that checks your tumor for many gene changes at once. It can find rare mutations and may open doors to additional options or clinical trials.
Knowledge Check
Test what you’ve learned
Three quick questions to help you feel more confident talking with your care team.
When should biomarker testing happen?
Based on what you just read, when is the best time to get biomarker testing for lung cancer?
What does EGFR-positive mean for a lung cancer patient?
Based on what you just read, what does an EGFR mutation in your tumor mean?
What does PD-L1 testing tell your doctor?
Based on what you just read, what is PD-L1 used for?
Keep these in mind for your next appointment.
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