Biomarker Resource Center
Leukemia Biomarkers
Reviewed by XpertPatient Medical Advisory · Updated August 2026 · Primary Source: cancer.gov
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What Is a Biomarker — and Why Does It Matter for Your Treatment?
A biomarker in leukemia is usually a specific gene change in your blood or bone marrow. These gene changes tell your doctor exactly what type of leukemia you have and which approaches are most likely to work.
Think of it like a clue. Your doctor collects clues from your biomarker test results. Those clues help build a picture of your cancer. That picture helps you have a more informed conversation with your care team about next steps.
How a Biomarker Test Works
A biomarker is a signal your cancer leaves behind. Your doctor finds it through a biopsy or blood test, reads your results, and uses them to choose the treatment most likely to work for your specific tumor.
Why Do Biomarkers Matter in Leukemia?
Leukemia is defined by specific gene changes. Two people with leukemia can have completely different diseases requiring completely different care. Genetic testing is the foundation of every leukemia diagnosis.
The most important leukemia biomarkers are BCR-ABL1, FLT3, and NPM1. Together they help define your specific leukemia subtype and guide the conversation about your care.
A good question to ask your doctor: Ask your doctor to explain your genetic test results in plain terms and what each result means for your specific type of leukemia.
Quick Poll
Have you been biomarker tested?
Your specific gene changes define your leukemia subtype and are the foundation of your entire care plan.
Source: DaCosta Byfield et al., JAMA Network Open, July 2025 · overall advanced cancer biomarker testing rate (n=26,311) · jamanetwork.com
The Tests Your Doctor May Order
Is there a specific gene fusion that defines your CML?
BCR-ABL1 is the gene fusion that causes chronic myeloid leukemia (CML). A targeted drug designed to block it has transformed CML into a condition many patients manage long-term. Ask your doctor what your result means.
Is there a mutation that gives your doctor information about your AML?
FLT3 mutations are found in 25 to 30% of AML cases and are linked to higher relapse risk. Targeted drugs that work against FLT3 are available. Ask your doctor whether FLT3 testing was done and what your result means.
Is there a mutation that can actually be good news?
NPM1 mutations — when found without a FLT3 mutation — are a favorable sign in AML. Patients with this profile tend to respond well to standard care. Ask your doctor what your NPM1 result means for your situation.
What do your chromosome test results show?
Chromosome analysis and FISH testing look for changes in the structure of your chromosomes. These results help classify your leukemia and tell your doctor how aggressive it may be. Ask your doctor to walk you through your chromosome results.
Sources: National Cancer Institute · LLS · American Cancer Society
Watch & Learn
Common Questions
Leukemia Biomarkers — Your Questions Answered
How is CML different from AML?
CML is driven by BCR-ABL1 and treated with daily oral targeted drugs. AML is more aggressive and treated with intensive chemotherapy. They are completely different diseases. Ask your doctor to explain exactly which type you have.
How often will my results be monitored?
In leukemia, biomarker results are often checked regularly. Ask your doctor how often your results will be checked and what changes to look for.
What does it mean if results change over time?
Changes give your doctor important information. Ask your doctor to explain any changes and what they mean going forward.
Should I ask about a second opinion?
Many patients find it helpful to get a second opinion after a leukemia diagnosis. Ask your doctor or patient navigator for help.
Knowledge Check
Test what you’ve learned
Three quick questions to help you feel more confident talking with your care team.
What is BCR-ABL1?
Based on what you just read, what does BCR-ABL1 define?
What does an NPM1 mutation without FLT3 mean?
Based on what you just read, how is an NPM1 mutation without FLT3 described?
Why is genetic testing so important in leukemia?
Based on what you just read, why does every leukemia patient need genetic testing?
Keep these in mind for your next appointment.
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