What does response to treatment mean?

During treatment for chronic lymphocytic leukemia (CLL), your healthcare team will monitor you closely to understand how treatment is working. This is often described as response to treatment. Monitoring for response to treatment may include:

• a complete blood count (CBC) and other blood chemistry tests to look at your blood cell levels
• a physical exam and imaging tests to check the size of your spleen and lymph nodes

Your healthcare team will use these tests to determine if the cancer is in remission or is relapsed or refractory.

Remission in CLL can be described as either complete remission or partial remission.

Complete remission (CR) means that for 2 months after treatment, you have had no symptoms of CLL, the blood cell levels are normal and the spleen and lymph nodes are not enlarged. After this 2-month period, lymphocytes should make up less than 30% of all blood cells.

Partial remission (PR) means that for 2 months after treatment, the number of lymphocytes in the blood has decreased by more than 50% and the lymph nodes, spleen and liver have decreased more than 50% in size if they were enlarged. As well, one or more of the following criteria must be met:

• The hemoglobin count is greater than 100 or it has increased by more than 50% from where it started (this is called the baseline).
• The neutrophil count is greater than 1.5 or it has increased by more than 50% from the baseline.
• The platelet count is greater than 100 or it has increased by more than 50% from the baseline.

Relapsed CLL is CLL that has come back 6 months or more after treatment has led to either complete remission or partial remission. Relapsed CLL is also called recurrent CLL.

Refractory CLL is CLL that did not respond to treatment. Another way of describing refractory cancer is to say that it is resistant to a treatment. The cancer may be resistant from the start of the treatment, or it may become resistant during treatment.