Chronic Myelocytic Leukemia
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Chronic Myelocytic Leukemia, or CML is a type of cancer that begins within the bone marrow. The soft spongy matter inside the bones known as the marrow helps in the formation of blood cells. CML develops from cells in the bone marrow that are responsible for producing white blood cells.

Chronic Myelocytic Leukemia commonly affects adults from the ages of 40 to 60 years old, although it may sometimes occur in people, regardless of age or gender.


CML is usually caused by the rearrangement of certain chromosomes in a person’s DNA. Two chromosomes in particular rearrange to form what is known as the Philadelphia chromosome. This rearranged pair brings about tyrosine kinase, an abnormal enzyme that in turn affects the growth patterns of white blood cells in the bone marrow. The Philadelphia chromosome is responsible for the abnormal number of white blood cells and platelets that are produced, and abnormal numbers of white blood cells are what lead to the occurrence of Chronic Myelocytic Leukemia.

As the disease progresses, increasing numbers of white blood cells appear in the bone marrow until it spreads out and enters a person’s bloodstream. While the disease progresses, these leukemia cells go through several changes. In its blast crisis phase, leukemia cells that are produced are only the immature ones, signaling that the CML has gotten worse. During this phase, a patient’s spleen becomes enlarged, and fever and weight loss start.

Chronic Myelocytic Leukemia affects approximately 2 in every 100,000 people, about 7 to 20% of all leukemia cases. It is caused by an abnormality in a person’s chromosomes known as the Philadelphia chromosome, and there are many factors that bring about this type of abnormal rearrangement.


When a person is exposed to radiation, it could trigger the occurrence of this type of chromosome abnormality. Radiation exposure can be the result of a nuclear disaster, or even previous chemotherapy treatment for another cancer such as Hodgkin’s lymphoma or thyroid cancer. However, not all patients treated with radiation therapy for other types of cancer develop CML, and a majority of CML patients have not had exposure to radiation.
Chronic Myelocytic Leukemia
Image: Chronic Myelocytic Leukemia

Chronic Myelocytic Leukemia causes blood-forming cells to undergo rapid growth within the bone marrow, body tissue, and blood. The disease goes through several phases, namely chronic, accelerated, and blast crisis. In its earlier stages, CML patients display no symptoms. However, there may be incidences of fatigue and weakness, loss in appetite and weight, as well as fever, excessive sweating at night, and a sensation of fullness. This sensation is due in part to a person’s enlarged spleen, another symptom of CML.

This chronic phase may last for an extended period of time, from a few months up to several years. There are very few symptoms that manifest themselves and the disease is usually detected when people get tested during routine medical exams.

The second phase of the disease, the accelerated phase, is considered very dangerous. This is the period where the leukemia cells that are produced start to grow very rapidly. During this phase, the patient will start to experience low-grade fevers that are not caused by any infection, a swollen spleen, and bone pain.

Untreated CML often takes the patient to the last phase known as the blast crisis. In this stage, the patient will experience a sharp drop in red blood cells and platelets, resulting in paleness, a tendency to bruise easily, and bleeding. Infection may occur at this stage in the disease, often stemming from bone marrow failure.

Other symptoms of Chronic Myelocytic Leukemia include the appearance of petechiae, small red marks on the surface of the skin, and pressure felt on the left rib cage that is caused by a swelling of the spleen.


Diagnosing Chronic Myelocytic Leukemia is as simple as having a complete blood count taken. This test will supply the doctor with data showing an abnormally high number of white blood cells. Examined further under a microscope, these white blood cells, previously found only in the bone marrow, are less mature.

To confirm that a person is suffering from suspected CML, tests that closely examine and analyze a person’s chromosomes need to be taken to determine the existence of the Philadelphia chromosome.


The doctor will conduct a physical examination to check for the presence of a swollen or enlarged spleen. The doctor may also order a CBC differential, aspiration of the bone marrow, genetic testing to determine the presence of the bcr-abl gene, a platelet count, and other tests to check the level of a person’s uric acid and vitamin B12.

Patients suffering from Chronic Myelocytic Leukemia are usually given imatinib (Gleevec) to block the Philadelphia chromosome and to keep it from producing the abnormal enzyme, tyrosine kinase, responsible for causing the rapid production of white blood cells. Gleevec has been recorded to be responsible for the high rates of patient remission from CML.

There are other medications such as dasatinib (Sprycel) and nilotinib (Tasigna) that doctors may prescribe, as well. Temporarily controlling the production of white blood cells, a type of chemotherapy medicine, hudroxyurea (Hydrea) is used to impede white blood cell production during the earlier stages of CML.

By the time CML reaches the blast crisis stage, the disease becomes very difficult to treat because of the huge number of immature white blood cells present.

To cure CML, a stem cell transplant, or bone marrow transplant may be necessary. Patients will need to discuss all their options with their oncologist in order to decide which form of treatment will work well for them, as well as to review the various other options for treatment.

When combined with high-dose chemotherapy sessions, stem cell transplantation may actually eradicate CML. Stem cell transplantation is very difficult because the stem cells need to be harvested from a donor with the same tissue type as the patient. To be effective, stem cell transplantation will need to be performed during the first stage of CML. Having a transplantation procedure done when the disease is in the accelerated or blast crisis stage will not work to treat the disease at all.

In a blast crisis that is not treated, the life expectancy of a person is a couple of months. CML therapy with imatinib (Gleevec) may extend a patient’s life for up to a year. Other medications such as busulfan (Myleran) and hudroxyurea (Hydrea) do not actually prolong a patient’s survival but are effective in relieving the symptoms of Chronic Myelocytic Leukemia.

With the advent of newer drugs such as imatinib (Gleevec), patients suffering from CML have a better outlook. The symptoms of the disease abate, and the patient goes on remission for up to several years while on imatinib. Patients who undergo stem cell transplantation can expect long-term cure from between 60% to 80%.
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