Chronic Myelogenous Leukemia

by National Cancer Institute

Chronic myelogenous leukemia is a disease in which the bone marrow makes too many white blood cells.

Chronic myelogenous leukemia (also called CML or chronic granulocytic leukemia) is a slowly progressing blood and bone marrow disease that usually occurs during or after middle age, and rarely occurs in children. Normally, the body produces bone marrow stem cells (immature cells) that develop into mature blood cells.

There are 3 types of mature blood cells:

• Red blood cells that carry oxygen and other materials to all tissues of the body.
• White blood cells that fight infection and disease.
• Platelets that help prevent bleeding by causing blood clots to form.

In CML, the body tells too many bone marrow stem cells to develop into a type of white blood cell called granulocytes. Some of these bone marrow stem cells never become mature white blood cells. These are called blasts. Over time, the granulocytes and blasts crowd out the red blood cells and platelets in the bone marrow.

Possible signs of chronic myelogenous leukemia include tiredness, night sweats, and fever.

These and other symptoms may be caused by CML. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur:

• Feeling very tired.
• Weight loss for no known reason.
• Night sweats.
• Fever.
• Pain or a feeling of fullness below the ribs on the left side.

Sometimes CML does not cause any symptoms at all.

Most people with CML have a gene mutation (change) called the Philadelphia chromosome.

Every cell in the body contains DNA (genetic material) that determines how the cell looks and acts. DNA is contained inside chromosomes. In CML, part of the DNA from one chromosome moves to another chromosome. This change is called the "Philadelphia chromosome." It results in the bone marrow making an enzyme, called tyrosine kinase, that causes too many stem cells to develop into white blood cells (granulocytes or blasts).

The Philadelphia chromosome is not passed from parent to child.

Tests that examine the blood and bone marrow are used to detect (find) and diagnose chronic myelogenous leukemia.

The following tests and procedures may be used:

Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease such as an enlarged spleen. A history of the patient's health habits and past illnesses and treatments will also be taken.

Complete blood count (CBC): A procedure in which a sample of blood is drawn and checked for the following:

• The number of red blood cells, white blood cells, and platelets.
• The amount of hemoglobin (the protein that carries oxygen) in the red blood cells.
• The portion of the sample made up of red blood cells.

Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease in the organ or tissue that produces it.

Cytogenetic analysis: A test in which cells in a sample of blood or bone marrow are viewed under a microscope to look for certain changes in the chromosomes, such as the Philadelphia chromosome.

Bone marrow aspiration and biopsy: The removal of bone marrow, blood, and a small piece of bone by inserting a needle into the hipbone or breastbone. A pathologist views the bone marrow, blood, and bone under a microscope to look for abnormal cells.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis (chance of recovery) and treatment options depend on the following:

• The patient's age.
• The phase of CML.
• The amount of blasts in the blood or bone marrow.
• The size of the spleen at diagnosis.
• The patient's general health.

Stages of Chronic Myelogenous Leukemia

After chronic myelogenous leukemia has been diagnosed, tests are done to find out if the cancer has spread.

Staging is the process used to find out how far the cancer has spread. There is no standard staging system for chronic myelogenous leukemia (CML). Instead, the disease is classified by phase: chronic phase, accelerated phase, or blastic phase. It is important to know the phase in order to plan treatment. The following tests and procedures may be used to find out the phase:

Cytogenetic analysis: A test in which cells in a sample of blood or bone marrow are viewed under a microscope to look for certain changes in the chromosomes, such as the Philadelphia chromosome.

Bone marrow aspiration and biopsy: The removal of bone marrow, blood, and a small piece of bone by inserting a needle into the hipbone or breastbone. A pathologist views the bone marrow, blood, and bone under a microscope to look for abnormal cells.

Chronic myelogenous leukemia has 3 phases.

As the amount of blast cells increases in the blood and bone marrow, there is less room for healthy white blood cells, red blood cells, and platelets. This may result in infections, anemia, and easy bleeding, as well as bone pain and pain or a feeling of fullness below the ribs on the left side. The number of blast cells in the blood and bone marrow and the severity of symptoms determine the phase of the disease.

Chronic phase

In chronic phase CML, fewer than 10% of the cells in the blood and bone marrow are blast cells.

Accelerated phase

In accelerated phase CML, 10% to 19% of the cells in the blood and bone marrow are blast cells.

Blastic phase

In blastic phase CML, 20% or more of the cells in the blood or bone marrow are blast cells. When tiredness, fever, and an enlarged spleen occur during the blastic phase, it is called blast crisis.

Relapsed Chronic Myelogenous Leukemia

In relapsed CML, the number of blast cells increases after a remission.

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