Chronic Myelogenous Leukemia (CML)

What Is Leukemia?

Leukemia is a cancer that mostly affects white blood cells. White blood cells (also called leukocytes) fight infections. 

Bone marrow is a spongy material inside the bones that makes white blood cells, red blood cells, and platelets. With leukemia (loo-KEE-mee-uh), the bone marrow makes white blood cells that don’t work. These abnormal cells can’t protect the body from germs. They crowd the bone marrow, enter the bloodstream, and can spread to other parts of the body, like the lymph nodes, brain, or liver.

Leukemia is the most common type of cancer in children. It can be acute (fast-growing) or chronic (slow growing). Most kids and teens treated for leukemia are cured of the disease.

What Is Chronic Myelogenous Leukemia?

Chronic myelogenous (mye-eh-LAH-jeh-nis) leukemia starts in early myeloid (MYE-uh-loyd) cells, which are blood cells that usually become white blood cells. These myeloid cells do not mature normally into white blood cells. Instead, they collect in the bone marrow and blood in large numbers.

Chronic myelogenous leukemia (CML) is also known as chronic myeloid leukemia.

What Are the Signs & Symptoms of Chronic Myelogenous Leukemia?

CML happens slowly. At first, a child may have few or no symptoms. Symptoms can take months or even years to start.

Kids with CML may get anemia, which is when the body has too few red blood cells. It happens when bone marrow stops making the usual amount of red blood cells.

Kids with anemia may:

• look pale
• feel very tired or weak
• get short of breath while playing

When they don’t have enough platelets (PLATE-lits), kids with leukemia may bruise easily, get nosebleeds, or bleed for a long time after even a minor cut.

Other symptoms of leukemia can include:

• pain in the bones or joints, sometimes causing a limp
• swollen lymph nodes (swollen glands) in the neck, groin, or elsewhere
• poor appetite and weight loss
• fevers
• belly pain

Because their white blood cells can't fight infections, kids with leukemia are more likely to get viral or bacterial infections.

Sometimes leukemia can spread, or metastasize (meh-TASS-tuh-size). If it spreads to the brain, symptoms may include headaches, seizures, balance problems, or vision problems. If it spreads to the lymph nodes in the chest, symptoms may include breathing problems and chest pain.

What Causes Chronic Myelogenous Leukemia?

CML is caused by a problem with chromosomes. Chromosomes have pieces of DNA called genes. With CML, a piece of a chromosome breaks off and attaches to part of another chromosome. This forms a mutated (changed) gene called BCR-ABL. This gene then guides the body to make too many abnormal white blood cells.

Researchers aren’t sure why this happens.

How Is Chronic Myelogenous Leukemia Diagnosed?

Because symptoms can take a long time to happen, doctors might find CML when a child has a blood test for another reason. Doctors check for leukemia with special tests. These include:

• Blood tests. Tests such as a complete blood count, liver function and kidney function panels, and blood chemistry tests can give important information about the number of normal blood cells in the body and how well the organs are working. The shapes and sizes of the blood cells are checked with a microscope.
• Imaging studies. These may include an X-ray, CT scan, MRI, or ultrasound. Doctors use these to rule out other causes of symptoms, or look for a mass of leukemia cells in the chest that can affect breathing or blood circulation.
• Bone marrow aspiration and biopsy. For this procedure, a child gets medicine to sleep and be comfortable. The doctor then puts a needle into a large bone, usually the hip, and removes a small amount of bone marrow. A lab does these tests on the bone marrow sample:
  • Flow cytometry tests. Doctors carefully look at the cancer cells and figure out the type and subtype of the leukemia. This is important because treatment varies among different types of leukemia.
  • Genetic tests. By looking carefully at the blood or bone marrow, doctors check for changes in the genes. This can help them figure out the best treatment.
  • Tissue typing or HLA (human leukocyte antigen) typing. If a child needs a stem cell transplant (sometimes called a bone marrow transplant), this test helps find a suitable stem cell donor. It compares the proteins on the surface of the child's blood cells with the proteins on a potential donor's cells. The more HLA markers a child and donor share, the greater the chances that a transplant will go well.
• Spinal tap (lumbar puncture). The doctor uses a hollow needle to remove a small amount of cerebrospinal fluid (the fluid surrounding the brain and spinal cord). The fluid is checked for cancer cells. This helps doctors plan treatment.

How Is Chronic Myelogenous Leukemia Treated?

How doctors treat CML depends on things like:

• the stage of the leukemia (whether it's in the early or later stages)
• the number of cancer cells in the body
• how well the liver, kidneys, and spleen are working
• the child's age and overall health

Treatments may include:

• Targeted therapy. Doctors use medicines to find and attack the cancer cells without hurting the normal cells. The medicines, called tyrosine kinase inhibitors (TKI), kill cancer cells and are usually the first treatment for patients with early CML.
• Chemotherapy. This uses special medicines to kill cancer cells. More than one type may be given to attack cancer cells in different ways.
• Rarely, stem cell transplant. This involves killing cancer cells and normal bone marrow and immune system cells with high-dose chemotherapy and then putting healthy donor stem cells into the body. The new stem cells can rebuild a healthy blood supply and immune system.

The goal is remission, which is when there is no trace of cancer cells in the body. Then, doctors use tyrosine kinase inhibitors to keep a child in remission and to keep killing cancer cells. The cancer team regularly checks how well treatment is working by doing blood tests and measuring how many abnormal genes are in the blood.

What Else Should I Know?

Having a child being treated for cancer can feel overwhelming for any family. But you're not alone. To find support, talk to anyone on your child’s care team or a hospital social worker. Many resources are available to help you get through this difficult time.

You also can find information and support online at:

• American Childhood Cancer Organization
  
• American Cancer Society
• National Children’s Cancer Society (NCCS)