Treatments for chronic myeloid leukemia

Your healthcare team will create a treatment plan just for you. The plan is based on your health and specific information about the cancer. What you want is also important when planning treatment. When deciding which treatments to offer for chronic myeloid leukemia (CML), your healthcare team will consider:

• the phase of CML
• your age
• your overall health
• any medical problems you have
• what treatments you have already been given
• your lifestyle and what you prefer or want

Targeted therapy with tyrosine kinase inhibitors (TKIs) is the main treatment for CML.

Your healthcare team will develop a plan to monitor how CML responds to treatment. This information will help them decide if you might need to have a different treatment.

A molecular response is based on the number of cells that have the BCR-ABL gene (CML cells). It is measured using a polymerase chain reaction (PCR) test.

When you are first diagnosed, you will have a PCR test to count the number of CML cells. You will then have a PCR test every 3 months to see if this number is changing. When the number of CML cells goes down, it means there is a molecular response to treatment.

• Early molecular response (MR) means that 10 out of every 100 cells (10%) are CML cells. It may be described as a 1-log reduction.

• Molecular response (MR2) means that 1 out of every 100 cells (1%) are CML cells. It may be described as a 2-log reduction.

• Major molecular response (MMR or MR3) means that 1 out of every 1,000 cells (0.1%) are CML cells. It may be described as a 3-log reduction.

• Deep molecular response (DMR or MR4 or MR4.5) means that 1 out of every 10,000 cells (0.01%) or 1 out of every 32,000 cells (0.003125%) are CML cells. It may be described as a 4-log reduction or a 4.5-log reduction.

• Complete molecular response means that 1 out of every 100,000 cells (0.001%) are CML cells. It may be described as a 5-log reduction.

It can take a year or longer after treatment starts to reach a molecular response. Once a molecular response has been maintained for more than 2 years, PCR tests are done less often (usually every 3 to 6 months).

The hematologic response is based on the numbers of different types of cells in the blood. It is measured using a complete blood count (CBC).

A complete hematologic response within 3 months is a favourable prognostic factor. It means that all of the following apply:

• The blood cell counts have returned to normal.
• Less than 5% of the cells in the blood are blast cells.
• The spleen can't be felt during a physical exam (which means that the leukemia cells aren't building up in it).
• CML isn't causing any symptoms.

A CBC will be done every week until your blood cell counts are stable. Then it will be done less frequently to monitor CML to see if it is progressing.