Biomarkers are specific changes or mutations inside cancer cells that make them different from healthy cells. These changes drive how cancer cells grow and spread. Knowing which biomarkers you have before your treatment begins is very important because it guides your healthcare team to your best treatment options.

Biomarker testing determines the cancer cells have “actionable” or “targetable” biomarkers. Having an actionable biomarker means certain treatments, like targeted therapy or immunotherapy, are more likely to work well for your specific type of lung cancer. If your results do not show an actionable biomarker, other lung cancer treatments or clinical trials may be an option.

If you’re diagnosed with non-small cell lung cancer (NSCLC), it’s vital to ask your healthcare team for comprehensive biomarker testing because it looks for all known biomarkers rather than just a few of them. Some cancer centers may automatically test for only the most common biomarkers, which can limit your treatment options if you have a less common biomarker.

If you’re diagnosed with small cell lung cancer (SCLC), biomarker testing may be done based on your specific case or in some SCLC clinical trials. Studies are underway to learn more about biomarkers in SCLC.

How biomarker testing is done

Your healthcare team can collect samples for biomarker testing in different ways based on your specific needs. Methods for biomarker testing include:


Tissue testing: During your initial biopsy or surgery, your healthcare team will collect tissue samples to test for cancer. Your pathologist will use these same samples for biomarker testing.

Liquid biopsy: A blood sample can sometimes be used to test for biomarkers because small pieces of cancer cells can be found in blood.

A liquid biopsy can be helpful when:

1. There isn't enough tissue from your original biopsy
2. Cancer has spread outside of the lung
3. You need repeat testing to check for new changes in your biomarkers
4. Getting another tissue biopsy would be difficult or risky

Your healthcare team will recommend which type of biomarker testing is right for you. There may be cases in which both tissue testing and liquid biopsy may be needed.

Understanding your biomarker testing results

When you receive your biomarker testing results, they will include a list of any biomarkers found in your tissue or blood sample. It usually takes up to 3 weeks to get results. While this may feel like a long wait, taking time to get complete and accurate results is very important to know the right treatment plan for your exact type of lung cancer.

Biomarkers and targeted therapy

If your biomarker test results show you have one or more actionable biomarkers, you will likely be given a targeted therapy as a treatment option. Each targeted therapy drug is made to work on a specific biomarker. When the targeted therapy drug finds the biomarker, it activates a process that causes the cancer cell to die.

Biomarkers are named after the specific changes or mutations found in cancer cells. Since these scientific names can be very long and complex, they are usually referred to by shorter symbols or abbreviations. When you receive your biomarker testing results, it will list which lung cancer biomarkers were found in your tissue or blood sample.

Biomarkers and immunotherapy

The protein level called PD-L1 is sometimes used to predict whether immunotherapy could work well for you. PD-L1 proteins are needed to help activate your body’s immune system when certain types of immunotherapy are used.

Cancer cells with higher levels of PD-L1 sometimes have a better response to immunotherapy than low levels of PD-L1. However, some people with low PD-L1 levels respond very well to immunotherapy, while others with high PD-L1 levels do not. This is especially true in people diagnosed with SCLC.