Chronic Myelogenous Leukemia (CML)

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.

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Anatomy of the bone. The bone is made up of compact bone, spongy bone, and bone marrow. Compact bone makes up the outer layer of the bone. Spongy bone is found mostly at the ends of bones and contains red marrow. Bone marrow is found in the center of most bones and has many blood vessels. There are two types of bone marrow: red and yellow. Red marrow contains blood stem cells that can become red blood cells, white blood cells, or platelets. Yellow marrow is made mostly of fat.

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.

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Blood cell development. A blood stem cell goes through several steps to become a red blood cell, platelet, or white blood cell.

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:

• Adult Acute Lymphoblastic Leukemia Treatment
• Childhood Acute Lymphoblastic Leukemia Treatment
• Acute Myeloid Leukemia Treatment
• Childhood Acute Myeloid Leukemia/Other Myeloid Malignancies Treatment
• Chronic Lymphocytic Leukemia Treatment
• Hairy Cell Leukemia Treatment

Signs and symptoms of chronic myelogenous leukemia include weight loss 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.
• Drenching 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.

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The Philadelphia (Ph) chromosome is an abnormal chromosome that is made when pieces of chromosomes 9 and 22 break off and trade places. The ABL gene from chromosome 9 joins to the BCR gene on chromosome 22 to form the BCR:: ABL fusion gene. The changed chromosome 22 with the fusion gene on it is called the Ph chromosome.

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

The following tests and procedures may be used:

• Physical exam and health 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.
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  Complete blood count (CBC). Blood is collected by inserting a needle into a vein and allowing the blood to flow into a tube. The blood sample is sent to the laboratory and the red blood cells, white blood cells, and platelets are counted. The CBC is used to test for, diagnose, and monitor many different conditions.
  

• 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.
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  Bone marrow aspiration and biopsy. After a small area of skin is numbed, a long, hollow needle is inserted through the patient's skin and hip bone into the bone marrow. A sample of bone marrow and a small piece of bone are removed for examination under a microscope.
  

  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 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 patient’s general health.

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

The extent or spread of cancer is usually described as stages. In chronic myelogenous leukemia (CML), 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 information from tests and procedures done to diagnose chronic myelogenous leukemia is also used to plan treatment.

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 signs or symptoms determine the phase of the disease.

Chronic myelogenous leukemia can relapse (return) after it has been treated.

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

There are different types of treatment for patients with chronic myelogenous leukemia.

Different types of treatment are available for patients with chronic myelogenous leukemia (CML). Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. A treatment clinical trial is a research study meant to help improve current treatments or obtain information about new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment. Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.

Six types of standard treatment are used:

High-dose chemotherapy with stem cell transplant

High doses of chemotherapy are given to kill cancer cells. Healthy cells, including blood-forming cells, are also destroyed by the cancer treatment. Stem cell transplant is a treatment to replace the blood-forming cells. Stem cells (immature blood cells) are removed from the blood or bone marrow of the patient or a donor and are frozen and stored. After the patient completes chemotherapy, the stored stem cells are thawed and given back to the patient through an infusion. These reinfused stem cells grow into (and restore) the body's blood cells.

See Drugs Approved for Chronic Myelogenous Leukemia for more information.

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Donor stem cell transplant. (Step 1): Four to five days before donor stem cell collection, the donor receives a medicine to increase the number of stem cells circulating through their bloodstream (not shown). The blood-forming stem cells are then collected from the donor through a large vein in their arm. The blood flows through an apheresis machine that removes the stem cells. The rest of the blood is returned to the donor through a vein in their other arm. (Step 2): The patient receives chemotherapy to kill cancer cells and prepare their body for the donor stem cells. The patient may also receive radiation therapy (not shown). (Step 3): The patient receives an infusion of the donor stem cells.

New types of treatment are being tested in clinical trials.

Information about clinical trials is available from the NCI website.

Treatment for chronic myelogenous leukemia may cause side effects.

For information about side effects caused by treatment for cancer, visit our Side Effects page.

Patients may want to think about taking part in a clinical trial.

For some patients, taking part in a clinical trial may be the best treatment choice. Clinical trials are part of the cancer research process. Clinical trials are done to find out if new cancer treatments are safe and effective or better than the standard treatment.

Many of today's standard treatments for cancer are based on earlier clinical trials. Patients who take part in a clinical trial may receive the standard treatment or be among the first to receive a new treatment.

Patients who take part in clinical trials also help improve the way cancer will be treated in the future. Even when clinical trials do not lead to effective new treatments, they often answer important questions and help move research forward.

Patients can enter clinical trials before, during, or after starting their cancer treatment.

Some clinical trials only include patients who have not yet received treatment. Other trials test treatments for patients whose cancer has not gotten better. There are also clinical trials that test new ways to stop cancer from recurring (coming back) or reduce the side effects of cancer treatment.

Clinical trials are taking place in many parts of the country. Information about clinical trials supported by NCI can be found on NCI’s clinical trials search webpage. Clinical trials supported by other organizations can be found on the ClinicalTrials.gov website.

Follow-up tests may be needed.

As you go through treatment, you will have follow-up tests or check-ups. Some tests that were done to diagnose or stage the cancer may be repeated to see how well the treatment is working. Decisions about whether to continue, change, or stop treatment may be based on the results of these tests.

Some of the tests will continue to be done from time to time after treatment has ended. The results of these tests can show if your condition has changed or if the cancer has recurred (come back).

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