Chronic Myelocytic Leukemia
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Chronic Myelocytic Leukemia

(CML; Chronic Myeloid Leukemia; Chronic Myelogenous Leukemia; Chronic Granulocytic Leukemia)

En Español (Spanish Version)

Definition

Chronic myelogenous leukemia (CML) is a cancer of the blood and bone marrow, in which the bone marrow makes abnormal myeloblasts (a type of white blood cell), red blood cells, or platelets. CML progresses gradually, often remaining indolent (slow growing) for many years. Eventually, it may transform itself into a more aggressive type of leukemia, acute myelogenous leukemia (AML), which progresses much more rapidly and is more serious.

Cancer occurs when cells in the body (in this case, myeloblasts—the bone marrow cells from which white blood cells are ultimately formed) become abnormal, and divide without control or order. Leukemia is cancer of the white blood cells and their parent cells. Leukemia cells do not function normally and cannot do what normal blood cells do, such as fight infection. This means that a person with leukemia is more likely to become infected with viruses or bacteria. Because the cancerous cells also overgrow the bone marrow, they can force out other normal components, such as the cells that make platelets. Platelets are necessary for proper blood clotting, so people with untreated leukemia may also have unexpected bleeding or may bruise easily.

White Blood Cells

White Blood Cells

© 2008 Nucleus Medical Art, Inc.

Causes

CML is almost always associated with a gene mutation in a chromosome called the Philadelphia chromosome. This mutation occurs during life and is not passed from parent to child. In most cases, the cause of the mutation is not known; however, studies show that exposure to large doses of radiation (such as in survivors or nuclear accidents or of the atomic bomb blasts) is associated with development of the Philadelphia chromosome and CML.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

The following factors increase your chance of developing CML:

  • Sex: male
  • Age: middle age or later
  • Exposure to atomic bomb radiation
    • The only risk factor that is clearly associated with CML is exposure to radiation; however, most patients with the condition have not been exposed to radiation.
  • Exposure to nuclear reactor accident
  • Smoking
    • Smoking is the only lifestyle factor that has been linked to leukemia, but its association with CML is still unclear.

Symptoms

Symptoms include:

  • Tiredness
  • Lack of energy
  • Fatigue
  • Unexplained weight loss
  • Night sweats
  • Fever
  • Pain or a feeling of fullness below the ribs
  • Bone pain
  • Joint pain
  • Reduced exercise tolerance
  • Enlargement of the liver or spleen
  • Unexplained bleeding or unusual bruising

These symptoms may also be caused by other, less serious health conditions. Anyone experiencing these symptoms should see a doctor.

Diagnosis

Your doctor will ask about your symptoms and medical history, and perform a physical exam. He or she may also check for swelling of the liver; spleen, or lymph nodes in the armpits, groin, or neck. You will likely be referred to an oncologist, a doctor who specializes in treating cancer.

Tests may include the following:

  • Blood tests—Blood tests are done to check for changes in the number or appearance of different types of blood cells.
  • Bone marrow aspiration—In a bone marrow aspiration, a sample of liquid is removed from the bone marrow to test for cancer cells. This test generally entails inserting a needle into the bone of the hip or breastbone to remove marrow and send it for testing.
  • Bone marrow biopsy —In a bone marrow biopsy, the doctor removes a sample of liquid bone marrow and a small piece of bone to test for cancer cells. This is almost always done by inserting a cutting needle into the bone of the hip and will be done at the same time as bone marrow aspiration.
  • Routine microscopic exam—Routine examination involves taking a sample of blood, bone marrow, lymph node tissue, or cerebrospinal fluid. Blood samples are taken from a vein in the arm. Other samples, such as lymph node tissue or spinal fluid, require more invasive procedures. Lymph node biopsy and CSF examination are unusual in the evaluation of CML.
  • Bone, blood marrow, lymph node tissue, or cerebrospinal fluid tests—These tests are done to distinguish among types of leukemia.
  • Cytogenetic analysis—This is a test to look for certain changes of the chromosomes (genetic material) of the white blood cells, most often to test for Philadelphia chromosome. This may be done by using a test known as the polymerase chain reaction.
  • Chest x-ray —X-rays of the chest may detect signs of lung infection.
  • CT scan —This type of x-ray uses a computer to make pictures of structures inside the body.
  • MRI scan —This test uses magnetic waves to make pictures of structures inside the body.
  • Ultrasound —This test uses sound waves to examine masses and organs inside the body.

Treatment

Talk with your doctor about the best treatment plan for you. Treatment options include:

Chemotherapy

Chemotherapy is the use of drugs to kill cancer cells. It may be given in many forms including: pill, injection, and via a catheter. The drugs enter the bloodstream and travel through the body killing mostly cancer cells, but also some healthy cells.

Other Drug Therapy

Two drugs called imatinib (Gleevec) and dasatinib (Sprycel) work to inhibit the molecule that triggers the development of leukemia and the gene that is associated with it. This medication is often used in early stages of CML.

Biologic Therapy

Biologic therapy is the use of medications or substances made by the body to increase or restore the body's natural defenses against cancer. This type of therapy is also called biological response modifier therapy.

High-dose Chemotherapy With Stem Cell Transplant

High doses of chemotherapy are followed by a transplantation of stem cells (immature blood cells) to replace blood-forming cells destroyed by cancer treatment. Stem cells are removed from the blood or bone marrow of the patient or donor, and infused into the patient.

Donor Lymphocyte Infusion

A donor’s lymphocytes (a type of white blood cell) are infused into the patient. The cancer cells do not recognize these cells and do not attack them.

Surgery

A splenectomy , which is surgery to remove the spleen, may be performed if the spleen has become enlarged from the leukemia or if other complications, usually involving blood clotting, develop because of involvement of the spleen.

Prevention

There are no guidelines for preventing CML. Since it is possible that smoking is associated with CML, you may reduce your risk by not smoking.

RESOURCES:

American Cancer Society
http://www.cancer.org

The Leukemia and Lymphoma Society
http://www.leukemia-lymphoma.org/hm_lls

National Cancer Institute
http://www.cancer.gov

CANADIAN RESOURCES

BC Cancer Agency
http://www.bccancer.bc.ca/default.htm

Canadian Cancer Society
http://www.cancer.ca

References:

Chronic myelogenous leukemia (PDQ): treatment. National Cancer Institute website. Available at: http://www.cancer.gov/cancertopics/pdq/treatment/CML/Patient . Accessed November 26, 2005.

Detailed guide: leukemia—chronic myeloid (CML). American Cancer Society website. Available at: http://www.cancer.org/docroot/CRI/CRI_2_3x.asp?rnav=cridg&dt=83 . Accessed November 26, 2005.



Last reviewed January 2008 by Igor Puzanov, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.


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