EGFR, ALK, KRAS: Your Lung Cancer Biomarker Questions Answered

If you or someone you love has just been diagnosed with non-small cell lung cancer (NSCLC), one of the first things the care team will talk about is biomarker testing. The results can decide whether the first treatment is a daily pill, immunotherapy, chemotherapy or a combination. For Lung Cancer Awareness Month, here are answers to the questions patients most often ask about these tests.

What Is Biomarker Testing, and How Is It Different From Genetic Testing?

Biomarker testing, also called tumor testing or tumor profiling, looks for genes, proteins and other substances in the cancer itself that help guide treatment. According to the National Cancer Institute (NCI), every person's cancer has its own pattern of biomarkers, and testing is routinely done for some cancers, including NSCLC.

This is not the same as genetic testing for inherited mutations, which looks for gene changes you were born with and can share with relatives. Most lung cancer biomarkers are changes that developed in the tumor, so they are not passed down in families. If a tumor result hints at an inherited change, your team may suggest a visit with a genetic counselor.

Which Lung Cancer Biomarkers Do Doctors Look For?

For stage 4 NSCLC, the National Comprehensive Cancer Network (NCCN) recommends broad molecular testing, which checks for many changes at once rather than one at a time. Each of the changes below has at least one FDA-approved targeted drug:

• EGFR mutations, treated with drugs such as Tagrisso (osimertinib)
• ALK rearrangements, treated with drugs such as Alecensa (alectinib) and Lorbrena (lorlatinib)
• KRAS G12C mutations, treated with Lumakras (sotorasib) or Krazati (adagrasib)
• ROS1 and RET rearrangements, BRAF V600E and HER2 mutations, MET exon 14 skipping and NTRK fusions, each with its own matched drugs

Testing also includes PD-L1, a protein that helps doctors judge how likely immunotherapy is to work when no targetable gene change is found. Newer drugs keep being added for these targets. CURE's coverage of KRAS drug data from ESMO 2026 shows how quickly that list is changing.

Is a Blood Test Enough, or Do I Need a Biopsy?

Most testing is done on tumor tissue from a biopsy or surgery. When a tumor is hard to reach with a needle, or when a biopsy is not safe, doctors can use a liquid biopsy, a blood test that looks for bits of tumor DNA in the bloodstream. NCI notes that two liquid biopsy tests, Guardant360 CDx and FoundationOne Liquid CDx, are FDA approved.

The two approaches are often used together. A blood test can return results quickly, while tissue gives the most complete picture. If a liquid biopsy finds nothing, that does not always mean no change is present, so a tissue test may still be needed.

Should I Wait for Results Before Starting Treatment?

This is a conversation worth having with your oncologist before the first infusion. Some targeted drugs work best as a first treatment, and starting immunotherapy before results return can complicate the choice later for people whose tumors turn out to have certain gene changes. NCI does not list a standard turnaround time, so ask your team how long your test is expected to take and what the plan is while you wait.

What If My Results Show No Targetable Change?

Many people with NSCLC do not have a change that matches a targeted drug. That result still matters, because it points the team toward immunotherapy, chemotherapy or both, guided by the PD-L1 result. It can also open doors to clinical trials, some of which enroll patients based on less common biomarkers.

Will Insurance Pay for It?

Costs depend on the test, the cancer type and the plan. NCI notes that Medicare and Medicaid cover some tests for advanced cancer, and private insurers often cover tests with enough evidence to guide treatment, while tests considered experimental usually are not covered. It is worth calling your insurer, or asking the hospital's financial counselor to check, before the sample is sent. Clinical trials that include biomarker testing may cover its cost.

Will I Need to Be Tested Again?

Possibly. Tumors can change over time, especially after months on a targeted drug, and a new biopsy or blood test can show why a treatment stopped working and which drug to try next. If your cancer grows or comes back, ask whether repeat testing makes sense before the next treatment is chosen.

For more on why testing matters, see Your Genees, Your Treatment: Biomarker Testing and Lung Cancer.

References

1. "Biomarker Testing for Cancer Treatment." National Cancer Institute. Updated Dec. 14, 2021.
2. "Non-Small Cell Lung Cancer Treatment (PDQ)–Patient Version." National Cancer Institute. Accessed Nov. 2, 2026.
3. "Actionable Biomarkers Determined from Broad Molecular Testing for Patients with Stage IV Non-small Cell Lung Cancer (NSCLC) to Inform Targeted Therapy." eCQI Resource Center, Centers for Medicare & Medicaid Services (citing NCCN Guidelines for Non-Small Cell Lung Cancer, Version 3.2023). Accessed Nov. 2, 2026.

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