Biomarker Resource Center
Multiple Myeloma 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 multiple myeloma is an abnormal protein made by myeloma cells — measurable in your blood or urine. Unlike most cancers, myeloma is tracked mainly through blood and urine tests.
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 Multiple Myeloma?
Myeloma cells make an abnormal protein called M protein. Measuring M protein is your doctor’s main way to see how active the disease is and whether treatment is working.
The most important multiple myeloma biomarkers are M protein, free light chains, and beta-2 microglobulin. Together they give your doctor a clear picture of disease activity and how well treatment is working.
A good question to ask your doctor: Ask your doctor what your M protein level is and how it will be tracked throughout your care.
Quick Poll
Have you been biomarker tested?
M protein and free light chain levels are your doctor’s main window into how your myeloma is behaving.
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 an abnormal protein in your blood or urine?
M protein is made by myeloma cells. It is measured by blood and urine tests. As treatment works, M protein falls. If it rises again, myeloma may be coming back. Ask your doctor what your M protein level is and what changes to watch for.
Are protein fragments from myeloma cells detectable in your blood?
Free light chains are pieces of M protein. The ratio of two types helps track disease activity alongside M protein. Ask your doctor what your free light chain results mean.
Does this protein level indicate how advanced the disease is?
Higher levels mean more disease burden. Along with albumin and LDH, it is used in the ISS staging system to classify your myeloma. Ask your doctor what your beta-2 microglobulin level means.
What do your chromosome test results show?
FISH testing on your bone marrow looks for specific chromosome changes linked to more aggressive myeloma. Ask your doctor what your FISH results showed.
Sources: National Cancer Institute · IMF · American Cancer Society
Watch & Learn
Common Questions
Multiple Myeloma Biomarkers — Your Questions Answered
How is M protein measured?
By a blood test called SPEP and a urine test called UPEP. Your doctor will explain what your levels mean and how often they will be checked.
What does it mean if M protein goes down?
A falling M protein level is generally a sign your myeloma is responding to treatment. Ask your doctor what changes mean for your care.
What is MRD testing?
MRD testing looks for myeloma even when standard tests show nothing. Ask your doctor whether MRD testing is relevant for your situation.
Is there a patient support community?
Yes. The MMRF at themmrf.org and the IMF at myeloma.org are trusted resources.
Knowledge Check
Test what you’ve learned
Three quick questions to help you feel more confident talking with your care team.
What is M protein?
Based on what you just read, what is M protein and why does it matter?
What does a falling M protein level usually mean?
Based on what you just read, what does it mean when M protein decreases during treatment?
What does FISH testing look for?
Based on what you just read, what does FISH testing on bone marrow detect?
Keep these in mind for your next appointment.
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