Chronic myeloid leukemia (CML) blast crisis phase is the last stage of the condition where there are large clusters of immature white blood cells, or blasts, in the bone marrow, organs, and tissue.
CML progresses in phases, starting with the chronic phase, accelerated phase, and the blast crisis phase, the last stage of this condition.
Doctors define which phase a person has by the number of blasts in the bone marrow and blood. In the blast crisis phase, blood or bone marrow samples show
This article discusses what CML blast crisis is, its symptoms, and treatment options. It also looks at the outlook for a person with this phase of CML and provides a brief overview of other phases of this condition.
CML is a
Healthy bone marrow contains 5% blasts, meaning a person will have five blasts for every 100 blood cells. During the first phase of CML, the chronic phase, the number of blasts increases but remains at less than 15%. CML progresses slowly and can take months or years to progress to the next phase.
During the accelerated phase of CML, the second phase, the number of blasts is higher. There may also be more white blood cells and fewer platelets. During the accelerated phase of CML, CML cells may grow quickly, and there may be mutations within other cells.
Blast crisis is the third and final stage of CML. This phase can occur after resistance to targeted therapy and due to additional gene mutations.
During this phase, the number of blasts is very high, at around 30%, meaning three in every 10 cells are blast cells. Blasts may also be present in organs and tissues outside the blood and bone marrow.
The blast crisis phase of CML is more difficult to treat and can be life threatening.
There are various symptoms of CML. A person may experience
- bone pain
- night sweats
- weight loss
- loss of appetite
- pain or fullness in the stomach
- enlarged spleen
However, these symptoms may also be a result of several conditions, including other cancers.
Symptoms of blood cell shortage
Several symptoms can indicate a shortage of blood cells. People with CML may experience these symptoms as the blasts replace red and white blood cells and platelets:
- anemia, a shortage of red blood cells
- leukopenia and neutropenia, a shortage of white blood cells, which can lead to an increase in the risk of infections
- thrombocytopenia, a shortage of blood platelets, which can lead to easy bruising and bleeding
If a person experiences any symptoms of CML, they should contact a doctor as soon as possible.
A person with blast crisis phase CML will likely receive treatment at a specialized center with experts in treating this condition.
Healthcare professionals will order two tests before deciding on treatment for blast crisis CML.
Doctors will need to determine whether the blast phase involves myeloid or lymphoid blast cells, which will influence the method of treatment they offer.
Additionally, people will need to undergo a CBR-ABL1 kinase domain mutation analysis, which checks for mutations in the gene that tyrosine kinase inhibitor (TKI) therapy targets. Certain mutations can make the protein in the gene more or less resistant to TKI therapy.
- targeted therapy with a TKI, such as nilotinib, imatinib mesylate, or dasatinib
- donor stem cell transplant
- high dose chemotherapy
- chemotherapy as palliative care
Without treatment, CML can be fatal in the blast crisis phase, with a median survival rate of approximately 2–3 years. However, research suggests that new therapies mean that, on average, people with CML will die 3 years earlier than those without CML.
According to the
- having accelerated or blast crisis phase CML
- being 60 years of age or older
- having an enlarged spleen
- having bone damage from leukemia growth
- having very low or high platelet counts
- having multiple chromosome changes in CML cells
- an increase in the number of eosinophils and basophils, which are types of white blood cells
Doctors will consider these factors when using the Sokal system, which develops a score to help predict a person’s outlook. This system can categorize people into low, intermediate, or high risk groups.
Healthcare professionals may also use the Euro score system, which considers the percentage of eosinophils and basophils in the blood. More of these cells can indicate a worse outlook.
There are two other phases of CML: the chronic phase and the accelerated phase.
The chronic phase is the first stage of CML.
A person may experience mild symptoms or none at all. People with this phase of CML will have a blast content under
The accelerated phase is the second stage of CML.
A doctor is likely to diagnose a person with this stage of CML if:
- their blast count is
- their blood has a low number of platelets due to CML
- at least 30% of their blood is blasts and promyelocytes, which may indicate blood cancer
- at least 20% of their blood is the white blood cell basophils
- the blood contains leukemia cells that have new chromosomal mutations
People with the accelerated phase of CML may experience symptoms such as fever, weight loss, and loss of appetite. Individuals typically do not respond as well to treatment as those with chronic phase CML.
Blast crisis phase is the third and final stage of chronic myeloid leukemia, a form of cancer where large amounts of immature white blood cells grow in the bone marrow, blood, organs, and tissue.
Without treatment for blast crisis CML, this condition is fatal, with a survival rate of around 2–3 years. Doctors will consider several factors, such as a person’s age and the phase of cancer, when calculating the outlook.
Treatment options include targeted therapy, stem cell transplants, and chemotherapy. Healthcare professionals will conduct tests to determine which treatment best suits each individual.