What biomarkers are 

Biomarkers are specific features of cancer cells that can provide more information about the cancer, including how it might respond to treatment.  

Biomarkers in non-small cell lung cancer 

In non-small cell lung cancer (NSCLC), biomarker testing is commonly used to help guide treatment. Samples – often from a biopsy – are tested in a laboratory to look for genetic changes or other features that may help match the cancer to specific treatments. 

Common biomarkers in non-small cell lung cancer include genetic changes in the following genes: 

• ALK  
• BRAF 
• EGFR 
• HER2 
• KRAS  
• MET 
• NTRK 
• RET  
• ROS1  

Additional biomarkers, such as KEAP1 and STK11, are also being studied because they may influence prognosis or response to some treatments, although they are not currently targeted by specific treatments.

It is also common to test for PD-L1, a protein found on the surface of some cells, which may be present at higher amounts on some cancer cells compared with normal cells. 

Because biomarkers can help doctors choose the most appropriate treatment, biomarker testing should be carried out as part of the initial diagnosis of non-small cell lung cancer. This testing is usually performed on tissue taken during a biopsy, although in some cases it can also be done using a liquid biopsy, a type of blood test. Getting biomarker test results quickly is important because they can help with treatment decisions. International guidelines encourage timely testing and rapid turnaround of results so the appropriate treatment can be started as soon as possible.

How biomarkers affect treatment 

If certain biomarkers are found, targeted therapy may be considered. Targeted therapies are medicines designed to act on cells with specific genetic changes or biomarkers.  

The level of PD-L1 can guide treatment options and helps to decide whether immunotherapy, such as pembrolizumab, should be used alone for treatment or in combination with chemotherapy. The use of immunotherapy also depends on the stage of disease and what other treatments patients have been given.  

If no actionable biomarkers are found, other treatments options may be used, such as chemotherapy, radiotherapy, or immunotherapy combinations. 

References

1. National Cancer Institute. Biomarker testing for cancer treatment. https://www.cancer.gov/about-cancer/treatment/types/biomarker-testing-cancer-treatment. Updated Dec 14, 2021. Accessed Mar 4, 2026. 

2. Cancer Research UK. Targeted and immunotherapy treatment for lung cancer. https://www.cancerresearchuk.org/about-cancer/lung-cancer/treatment/immunotherapy-targeted. Last reviewed Jan 14, 2026. Accessed Mar 4, 2026. 

3. Cancer Research UK. Tests for lung cancer. https://www.cancerresearchuk.org/about-cancer/lung-cancer/getting-diagnosed/tests-for-lung-cancer. Last reviewed Oct 8, 2025. Accessed Mar 4, 2026. 

4. National Cancer Institute. Non-small cell lung cancer treatment (PDQ®)–patient version. https://www.cancer.gov/types/lung/patient/non-small-cell-lung-treatment-pdq. Updated May 16, 2025. Accessed Mar 4, 2026.