Biomarker Testing for Lung Cancer

All the cells in your body have instructions in their genes. These genetic instructions tell the cells how to work and when to die. When changes occur in the genes, cells change their normal behavior. These genetic changes may be called mutations. Mutations can cause normal cells to become cancer cells, among other things.

Some genetic changes are inherited or passed down from parents. The genetic changes that lead to lung cancer are often caused by long-term exposure to pollutants like smoke, certain industrial chemicals, or radon.

What is biomarker testing?

Doctors have found that there are specific genetic changes, or mutations, that occur in certain types of lung cancer. Biomarker (genetic) testing is a way to figure out what type of genetic changes are unique to a person’s lung cancer.¹

Knowing the mutations may help predict how a cancer will progress over time, or how aggressive it is. This information may help predict how a cancer might respond to treatment.

Biomarker testing can be done on cells taken during a biopsy. A biopsy is a surgery in which a small amount of cells are taken from a tumor or other tissue. These cells are analyzed under a microscope to help diagnose cancer. These cells can also be sent to a lab to determine their genetic makeup. This second step is where specific mutations might be identified.

Most experts now recommend testing for all relevant biomarkers at once using a broad, panel-based approach, often called next-generation sequencing (NGS), rather than testing for one mutation at a time. This approach is faster and less likely to miss a treatable mutation. For people with no known driver mutation, especially those who never smoked, doctors may also recommend a type of NGS testing that looks at RNA, which can catch gene fusions that standard DNA testing sometimes misses.²

When is genetic testing for lung cancer recommended?

Biomarker testing is most often done to plan treatment for advanced non-small cell lung cancers (NSCLC). But it may be useful for some early-stage lung cancers or if lung cancer recurs (returns after treatment).²

Not everyone with lung cancer will have known biomarkers. For example, people with a subtype of NSCLC called adenocarcinoma may have EGFR, ALK, ROS1, BRAF V600E, KRAS, HER2, MET, RET and NTRK mutations. So, if someone has NSCLC adenocarcinoma, biomarker testing may be helpful in finding a drug that targets one of its mutations.¹

Current guidelines recommend biomarker testing for people with advanced NSCLC regardless of histology, including squamous cell, and regardless of smoking history. This is a shift from older guidance, which limited squamous cell testing mostly to people who never smoked.²

Genetic testing is less commonly used for small cell lung cancer, which is biologically different from NSCLC.

Everyone with NSCLC should generally have their tumors tested for PD-L1 protein. This biomarker can tell your doctor if you are a good candidate for certain types of immunotherapy.¹

Types of lung cancer biomarkers

Some of the known biomarkers that may be tested for in people with lung cancer include:^1-5

• PD-L1 protein
• ALK
• ATM
• BRAF V600E
• CDKN2A
• DDR2
• DLL3
• EGFR
• FGFR
• HER2 (ERBB2)
• KEAP1
• KRAS
• MET exon 14 skipping
• NF1
• NTRK
• PIK3CA
• PTEN
• RET
• ROS1
• STK11
• TMB
• TP53

The tests may show the mutation of a gene, a rearrangement, a deletion, or an amplification. These are just some of the biomarkers linked to lung cancer. The list of FDA-approved treatments targeting specific biomarkers keeps growing each year, with far more options available today than just a few years ago.^4,5

Things to know about genetic testing

Biomarker testing should be done with the guidance of a trained genetic counselor. Genetic counselors may be part of your treatment team. Or, this may be a service your doctor will refer you to.

This person can explain what your test results mean. They will also be able to help you think through next steps and what the results may mean to your family. They can provide resources for emotional support and help you get the best care.

If you have questions about biomarker testing, talk with your doctor. If biomarker testing has not already been done, you can ask whether it may be helpful in your treatment plan.