Staging is a way of describing or classifying a cancer based on the extent, or amount, of cancer in the body. Cancers that form solid tumours are given numbered stages based on the size of the tumour and if the cancer has spread to lymph nodes or other parts of the body.
Chronic myelogenous leukemia (CML) is not staged in the same way as other types of cancer because it is a cancer of the cells in the blood-forming tissue in the bone marrow and doesn’t form a solid tumour. Instead of stages, CML is given a phase based on blood cell counts and symptoms.
CML usually progresses through each of these phases. Sometimes it can progress from the chronic phase directly to the blast phase. Most people are diagnosed in the chronic phase, but sometimes the blast phase is the first sign of CML.
In the chronic phase:
In the accelerated phase, any of the following apply:
When leukemia is in the accelerated phase, it can quickly progress to the blast phase. When this happens, it is called a blast crisis.
The blast phase is also called the acute phase or blast crisis. In this phase, the CML acts more like an acute leukemia:
Relapsed, or recurrent, CML means that the number of blast cells in the blood and bone marrow increase after treatment and reaching remission. Remission means that the blood cell counts have returned to normal and stay at or near normal levels for long periods of time.
Refractory disease means the leukemia did not respond to treatment.