What Is CLL vs. SLL?

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Dr. William Wierda from MD Anderson Cancer Center in Houston explains the difference between CLL (chronic lymphocytic leukemia) and SLL (small lymphocytic lymphoma). He also discusses prognosis and treatment for each condition.

The Ask the Expert series is sponsored through an educational grant to the Patient Empowerment Network from Pharmacyclics, Inc.

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Transcript

Please remember the opinions expressed on Patient Power are not necessarily the views of our sponsors, contributors, partners or Patient Power. Our discussions are not a substitute for seeking medical advice or care from your own doctor. That’s how you’ll get care that’s most appropriate for you.

Jeff Folloder:

Dr. Wierda, this can sometimes be confusing for patients. Is there a difference between CLL and SLL?

Dr. Wierda:

So that's a great question.  That's a question that I get asked a lot in clinic.  The difference is a numerical difference.  It's a numerical difference in terms of the blood count, the absolute lymphocyte count. For CLL, the absolute lymphocyte count is over 5,000. For SLL, or small lymphocytic lymphoma, the absolute lymphocyte count in the blood is less than 5,000.  So that's really the only difference.

In terms of a diagnosis, making a diagnosis, the CLL cells or SLL cells are evaluated by flow cytometry.  If it's a patient who has CLL, they have an elevated lymphocyte count, the flow cytometry can be performed on blood because the cells are in the blood.  If we have a patient with SLL, they don't have an elevated lymphocyte count in their blood. So we have to go to other tissues, whether it's a bone marrow or typically those patients with SLL will present with enlarged lymph nodes and we biopsy a lymph node.

When we—so when we look at the cells with flow cytometry or we evaluate the cells by flow cytometry, both CLL and SLL have the same protein signature on the cell surface.  That is, they both express—both CLL and SLL express CD5, CD19, CD2 and either kappa or lambda light chain.  Those are the—that's a simplified version of the signature that we look for to make a diagnosis.

So both SLL and CLL cells look by the proteins they have on their surface like the same thing.  Clinically, they behave similarly except—again the difference is that with CLL patients have an elevated lymphocyte count, with SLL they don't have an elevated lymphocyte count.

Otherwise, the disease entities are the same.

The prognostic factors hold for both, so unmutated patients with SLL or CLL have—tend to have a more active progressive clinical course.  Patients who have the high-risk chromosome abnormalities, whether they're SLL or CLL diagnosis, if they have those high-risk features, their disease behaves more aggressively.

The treatments are essentially the same for SLL as we use for CLL, chemoimmunotherapy.  There's less data right now on some of these newer agents like ibrutinib (Imbruvica) and the activity among the patients who have SLL, but I think with time we'll get—we'll get that data and as more patients are treated with those newer agents.  But with our standard chemotherapy, chemoimmunotherapy the clinical management is the same between SLL and CLL.

Please remember the opinions expressed on Patient Power are not necessarily the views of our sponsors, contributors, partners or Patient Power. Our discussions are not a substitute for seeking medical advice or care from your own doctor. That’s how you’ll get care that’s most appropriate for you.

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Page last updated on March 22, 2016