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. Tissue 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

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.

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

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.
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.
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.
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.