Like polycythaemia vera rubra and osteomyelosclerosis, CML is one of the myeloproliferative neoplasms. A disease of the bone marrow.
The incidence (incidence of disease) istwo per 100,000 inhabitants per year. People between the ages of 50 and 60 are most frequently affected.
CML is caused by a change in the multipotent hematopoietic progenitor cells. These blood stem cells are mainly found in the bone marrow.
They are responsible for the entire production of blood cells and the immune system. In CML, one of these stem cells degenerates and produces uncontrolled white blood cells, the granulocytes.
And in very large quantities. Although these are functional , they displace the other cells in the bone marrow and later also in the blood.
It is not yet clear exactly why stem cells degenerate. Triggering factors may be benzene, ionizing radiation (such as that emitted by radioactive substances) and chemotherapeutic agents.
In addition, experts have detected the Philadelphia chromosome in around 90 percent of patients with chronic myeloid leukemia. A connection between this chromosomal break in the chromosome 22 region and the development of CML is therefore very likely.

Chronic myeloid leukemia can basically be divided into three stages:
- Chronic phase
- Acceleration phase
- Blast crisis
The chronic phase begins gradually. Those affected often do not notice that they are ill for years. Swelling of the spleen (splenomegaly) is often the first and only symptom of the chronic phase.
As degenerated cells displace healthy blood formation from the bone marrow, the body produces blood in the liver and spleen. This leads to swelling of the organs. This can cause a feeling of pressure in the upper abdomen. However, CML is often diagnosed by chance at this stage.
For example, a routine blood test reveals an increase in white blood cells. Doctors refer to this as leukocytosis. Typically, not only mature granulocytes (a type of leukocyte) appear in the blood count, but also immature precursors. At this stage, the proportion of immature cells (blasts) is still below ten percent.
The acceleration phase marks the transition from the chronic phase to the blast phase. The number of white blood cells in the blood increases steadily. At the same time, there is a shortage of red blood cells and platelets.
Anemia manifests itself in the following symptoms:
- tiredness
- susceptibility to infections
- paleness
- hair loss
- headaches
- Shortness of breath on exertion
The lack of blood platelets (thrombocytes) leads to an increased tendency to bleed. Patients suffer more frequently from nosebleeds or develop larger hematomas from minor injuries.
Punctiform skin bleeding (petechiae) and bruising (hematomas) are common @ Eberhard /AdobeStock
The acceleration phase is characterized by a significant increase in splenomegaly. The blast rate in the blood count is now up to 30 percent.
Patients feel significantly weakened and their general condition is poor. In most cases, the blast crisis occurs suddenly after the acceleration phase or directly after the first phase.
The slow progression turns into an acute illness. The proportion of immature cells in the blood is more than 30 percent. Larger quantities of CML cells are now also found outside the bone marrow. In the blast crisis, patients feel very poorly.
They suffer from
- Increased susceptibility to infections
- tiredness
- fatigue
If left untreated, this stage ends fatally within a few days or weeks.
CML cannot currently be cured with medication.
The aim of drug therapy is to prevent the next stage of the disease and improve the patient's quality of life. The doctors check the success of the treatment based on the hematological, cytogenetic and molecular remission.
The success of the treatment is based on
- Degree of normalization of the blood count
- Decrease in swelling of the spleen
- Other laboratory parameters in blood and bone marrow tests
Doctors examine these regularly. At best, the blood count normalizes within a few days of starting treatment.
In most cases, treatment begins with medication from the group of tyrosine kinase inhibitors. These are drugs that inhibit a certain enzyme activity and thus also the division activity of the leukemia cells.
Well-known active substances from this group are
The administration of interferon-α is also part of the standard therapy for CML. IFN-α is a messenger substance that inhibits the division of leukemia cells. However, therapy with cytokine (cell growth-regulating protein) often leads to side effects. These lead to premature discontinuation of therapy.
In more severe forms of CML, normalization of the white blood cells can also be achieved with the cytostatic drug hydroxycarbamide. Chemotherapeutic agents such as hydroxycarbamide are used for high leukocyte counts or in preparation for a stem cell transplant.
Stem cell transplantation is the only treatment method that promises a cure for CML. The patient receives purified and filtered blood stem cells from a donor by infusion.
However, in order for the treatment to be effective, the patient first receives chemotherapy and radiation to kill the pathological bone marrow cells.
As not only diseased but also healthy cells die in the process, stem cell transplantation is no longer possible in more advanced stages of the disease.