Myeloma Therapy: Understanding Free Light Chain Assays
Learn more about the use of this blood test and how it is used in multiple myeloma therapy.
By Chris Iliades, MD
Medically Reviewed by Niya Jones, MD, MPH
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If you have been diagnosed with multiple myeloma, a blood test called a serum free light chain assay (Freelite) played an important role in your diagnosis and will continue to be important in determining your myeloma therapy. It's a little complicated, but it is important for you to understand the basics.
Myeloma Therapy: What Are Free Light Chains?
Myeloma is a cancer of a type of white blood cells called plasma cells. These cells come from the bone marrow and produce antibodies (or immunoglobulin) that are important in fighting infections. In myeloma, the abnormal plasma cells produce too much of one type of immunoglobulin called the M-protein. M-proteins crowd out all the other normal bone marrow cells, which eventually leads to the symptoms of myeloma.
The M-protein is made up of two types of molecules: heavy chain molecules and light chain molecules. For reasons we don't yet understand, the body produces more light chain molecules than it needs, so there are always free light chain molecules circulating in your blood. As abnormal myeloma cells produce more and more M-proteins, the level of free light chain molecules rises in the blood. A relatively new test called the serum free light chain assay, or free light assay, allows your doctor to monitor the status of your disease with a simple blood test.
"Some patients with myeloma produce only a part of the immunoglobulin called the 'light chain' or Bence-Jones protein," says Cristina Gasparetto, MD, a multiple myeloma research expert at the Duke University Comprehensive Cancer Center in North Carolina. "The light chain protein is a smaller protein and is not easily detected in blood using the standard protein electrophoresis test. The serum free light assay is much more sensitive than the regular electrophoresis to detect light chain myeloma."
How Free Light Tests Help Monitor Myeloma Therapy
There are two types of light chains: kappa and lambda chains. Since we now know the normal levels of these light chains, your doctor can monitor any changes in the levels during your treatment. "The ratio or proportion between the kappa and lambda light chains indicates an excess production of one chain over the other, and therefore can be used as an indication of disease progression or remission," says Dr. Gasparetto. In contrast to older tests used to monitor myeloma, free light assays can identify even slight increases in light chain levels. This permits doctors to adjust your treatment much more quickly.
The International Myeloma Foundation says that serum free light chain assays offer the following advantages in myeloma therapy:
- Improved ability to screen for and diagnose myeloma
- Rapid detection of response to treatment
- Earlier detection of relapse
- Capacity to predict risk of relapse
Myeloma Light Chain: Bottom Line in Myeloma Therapy
"In patients with multiple myeloma, the free light chain assay is important in predicting response to therapy and for predicting early signs of relapse," Gasparetto says.
Video: Dr Judith Finlay - Understanding the Serum Free Light Chain Assays
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