Leukemia - Chronic Myeloid - CML: Phases

This section has been reviewed and approved by the Cancer.Net Editorial Board, 06/2013

ON THIS PAGE: You will learn about how doctors describe the growth or spread of CML. This is called the phase. To see other pages, use the menu on the side of your screen.

To help doctors plan treatment and predict prognosis (chance of recovery), CML is divided into three different phases: chronic, accelerated, or blastic.

Chronic phase. The blood and bone marrow contain less than 5% blasts (immature white blood cells). This phase can last for several years, although without effective treatment the disease can progress to the accelerated or blast phases (see below). About 90% of people have chronic phase CML when they are diagnosed. Some people with chronic phase leukemia have symptoms when they are diagnosed and some do not; most symptoms go away once treatment begins.

Accelerated phase. In the accelerated phase, there are more than 5%, but less than 30% blasts in both the blood and bone marrow. These cells sometimes have new cytogenetic changes in addition to the Philadelphia chromosome, because of additional DNA damage and mutations in the CML cells.
Blast phase (also called blast crisis). In the blast phase, there are more than 30% blasts in the blood or bone marrow, and it is difficult to control the number of white blood cells. Additional genetic changes are also often found in the CML cells. The blast cells can look like the immature cells seen in acute lymphoblastic leukemia (for about 25% of patients) or acute myeloid leukemia (for most patients). Patients in blast crisis often have a fever, an enlarged spleen, weight loss, and generally feel unwell.

Recurrent CML. Recurrent CML is CML that has come back after treatment.

Without effective treatment, patients with CML in chronic phase will move into blast crisis in about four to five years after diagnosis. Patients who have more blasts or an increased number of cells called basophils (a special type of white blood cell), chromosome changes in addition to the Philadelphia chromosome, high numbers of white blood cells, or a very enlarged spleen often experience blast crisis sooner.

Information about the cancer’s phase will help the doctor recommend a treatment plan.  The next section helps explain the treatment options for this type of cancer. Use the menu on the side of your screen to select Treatment Options, or you can select another section, to continue reading this guide.