Lymphoma CD Tumor Markers

How Lymphoma Markers Aid in Diagnosing Lymphoma at the Molecular Level

What are lymphoma markers and why are they important?. Credit: Istockphoto.com/Stock Photo©gevende

What are lymphoma tumor markers, or CD markers?  Why are they important and how do they play a role in the treatment of lymphomas?

The Importance of CD Lymphoma Markers 

Determining CD markers on lymphomas is critical in selecting the best treatments for these diseases, but has not always been available. Let's take a look at the history in order to understand the importance of these tests in determining the best treatment for your cancer.

Why Lymphoma Markers are Important 

Try to imagine a single type of cell giving rise to nearly thirty different types of cancer - all with one name. Different lymphomas may be present in your lymph nodes, as a mass in your brain, as a disease of your stomach, or as lesions all over your skin. It's not simply a matter of location - a lymphoma found in any of these locations could be one of many types.  And choosing the best treatment depends on knowing the specific type.

The Microscope Isn't Enough to Diagnose Lymphomas

Even a couple of decades back, what the pathologist saw under the microscope with simple stains was all that we had to identify the type of lymphoma. And there were only a few types of lymphoma that could be distinguished. However, it often turned out that the behavior of the same type of tumor was different in different individuals. Clearly, we were missing something.

The Clue Is in the Molecules

As medicine moved from cells to molecules, techniques were devised to identify some specific molecules that were found on the surface of cells.

When these were applied to lymphoma cells, things took a dramatic turn. It turned out that lymphomas were not simply a handful of different types, but a lot more complicated.

What are Lymphoma CD markers?

On the surface of lymphocytes, the cells that are transformed to lymphomas, lie some unique molecules.

These were named 'cluster differentiation' or CD markers.  As normal lymphocytes develop from new cells to mature cells, these markers change. It was found that lymphomas that previously looked similar under the microscope had different markers on their surface. When that happened, they acted like different diseases altogether.

Lymphoma CD Markers in Diagnosis

Today, the diagnosis of lymphoma simply isn't complete unless a couple of lymphoma markers are first identified. To put a particular lymphoma in the proper group, immunohistochemistry is used to detect these specific molecules on cells of biopsy samples.

We now have specific drugs that attack CD molecules on the surface of some lymphoma cells.  These medications - termed monoclonal antibodies - attack only cells that have a particular CD marker.

A specific example can make this much easier to understand.  With lymphomas, it can be difficult if not impossible to tell the difference between a few cancer types.  Some lymphomas are B cell lymphomas and some are T cell lymphomas, but B cells and T cells can look identical under the microscope.

  Though they look identical, cancers involving these cells can behave very differently and respond differently to different medications.

CD20 is a marker or antigen found on the surface of B cells but not T cells. Diffuse large B cell lymphoma (DLBCL) - a cancer of B cells - can look identical to anaplastic large cell lymphoma - a cancer of T cells - under the microscope.  An immunohistochemistry test, however, can confirm the presence of CD20 - the antigen found on B cells to confirm that a cancer is DLBCL and not anaplastic large cell lymphoma.  Anaplastic large cell lymphoma, in contrast, can be distinguished by the presence of the CD30 antigen.

Lymphoma Markers in Determining Treatment and Prognosis

It doesn't stop there. Some special markers (one of them called bcl-2) can even tell the doctor how well your disease will fare. Some others (like CD20) are a pointer to whether a particular treatment will work. Examples of CD markers targeted in lymphoma treatment include the monoclonal antibody Rituxan (rituximab) which targets the CD20 antigen present on the surface of some lymphoma cells as well as some chronic lymphocytic leukemia cells.

As more and more research goes into these markers, new uses are coming up all the time. Truly, lymphoma has entered an era of molecules.

Sources:

National Cancer Institute. Tumor Markers. Updated 11/04/15. http://www.cancer.gov/about-cancer/diagnosis-staging/diagnosis/tumor-markers-fact-sheet

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