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Chronic Myeloid Leukemia Library

Learn about Chronic Myeloid Leukemia

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.

Leukemia may affect red blood cells, white blood cells, and platelets.

Normally, the bone marrow makes blood stem cells (immature cells) that become mature blood cells over time. A blood stem cell may become a myeloid stem cell or a lymphoid stem cell. A lymphoid stem cell becomes a white blood cell.

A myeloid stem cell becomes one of three types of mature blood cells:

  • Red blood cells that carry oxygen and other substances to all tissues of the body.
  • Platelets that form blood clots to stop bleeding.
  • Granulocytes (white blood cells) that fight infection and disease.

In CML, too many blood stem cells become a type of white blood cell called granulocytes. These granulocytes are abnormal and do not become healthy white blood cells. They are also called leukemia cells. The leukemia cells can build up in the blood and bone marrow so there is less room for healthy white blood cells, red blood cells, and platelets. When this happens, infection, anemia, or easy bleeding may occur.

This summary is about chronic myelogenous leukemia. See the following PDQ summaries for more information about leukemia:

Signs and symptoms of chronic myelogenous leukemia include fever, night sweats, and tiredness.

These and other signs and symptoms may be caused by CML or by other conditions. Check with your doctor if you have any of the following:

  • 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 a protein, called tyrosine kinase, that causes too many stem cells to become 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) with differential: A procedure in which a sample of blood is drawn and checked for the following:
    • The number of red blood cells and platelets.
    • The number and type of white blood cells.
    • The amount of hemoglobin (the protein that carries oxygen) in the red blood cells.
    • The portion of the blood 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.
  • 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.

    One of the following tests may be done on the samples of blood or bone marrow tissue that are removed:

    • Cytogenetic analysis: A laboratory test in which the chromosomes of cells in a sample of blood or bone marrow are counted and checked for any changes, such as broken, missing, rearranged, or extra chromosomes. Changes in certain chromosomes, such as the Philadelphia chromosome, may be a sign of cancer. Cytogenetic analysis is used to help diagnose cancer, plan treatment, or find out how well treatment is working.
    • FISH (fluorescence in situ hybridization): A laboratory test used to look at and count genes or chromosomes in cells and tissues. Pieces of DNA that contain fluorescent dyes are made in the laboratory and added to a sample of a patient’s cells or tissues. When these dyed pieces of DNA attach to certain genes or areas of chromosomes in the sample, they light up when viewed under a fluorescent microscope. The FISH test is used to help diagnose cancer and help plan treatment.
    • Reverse transcription–polymerase chain reaction test (RT–PCR): A laboratory test in which the amount of a genetic substance called mRNA made by a specific gene is measured. An enzyme called reverse transcriptase is used to convert a specific piece of RNA into a matching piece of DNA, which can be amplified (made in large numbers) by another enzyme called DNA polymerase. The amplified DNA copies help tell whether a specific mRNA is being made by a gene. RT-PCR can be used to check the activation of certain genes that may indicate the presence of cancer cells. This test may be used to look for certain changes in a gene or chromosome, which may help diagnose cancer.

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.

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