About Leukemia

Leukemia is a type of cancer that affects the body's white blood cells (WBCs).

Normally, WBCs help fight infection and protect the body against disease. But in leukemia, WBCs turn cancerous and multiply when they shouldn't, resulting in too many abnormal WBCs, which then interfere with organ function.

If too many lymphoblasts (a certain type of WBC) are produced, a child will develop acute lymphoblastic, or lymphoid, leukemia (ALL). This is the most common type of childhood leukemia, affecting about 75% of kids with this cancer of the blood cells. Kids ages 2 to 8 are more likely to be affected, but all age groups can develop ALL.

Thanks to advances in therapy and clinical trials, the outlook for kids with ALL is promising. With treatment, about 85% are cured.

Causes

The cause of ALL is not known. However, certain risk factors might increase a child's chance of developing it.

Kids with an identical twin who was diagnosed with the illness before age 6 have a 20% to 25% chance of developing ALL. Fraternal twins and other siblings of children with leukemia have two to four times the average risk of developing it, too.

Children who have inherited certain genetic problems (such as Li-Fraumeni syndrome, Down syndrome, Klinefelter syndrome, neurofibromatosis, ataxia telangiectasia, or Fanconi anemia) also have a higher risk of developing leukemia, as do those who are receiving medicines to suppress their immune systems after organ transplants.

Kids who have received radiation or chemotherapy for other types of cancer also have a higher risk, usually within the first 8 years after treatment.

In most cases, however, neither parents nor children have control over the factors that trigger leukemia. Current studies are investigating the possibility that some environmental factors may predispose a child to develop the disease. For example, prenatal radiation exposure (such as X-rays) may trigger ALL in a developing fetus. Women who are pregnant (or suspect they're pregnant) should inform their doctors before undergoing tests or medical procedures that involve radiation.

Signs and Symptoms

All types of leukemia generally have the same symptoms, which include:

• fatigue and weakness
• swollen lymph nodes
• recurrent infections (like bronchitis or tonsillitis)
• fever
• easy bruising
• bone and joint pain
• abdominal pain (caused by abnormal blood cells accumulating in organs like the kidneys, liver, and spleen)

Diagnosis

The subtypes of ALL are classified according to the proteins found in the leukemia cells. This requires special tests. A doctor who suspects a child has leukemia might order these tests:

• Blood tests. Tests such as a complete blood count, liver and kidney function panels, and blood chemistries can give important information about the number of normal blood cells in the body and how well the organs are functioning. The blood cells will also be examined under a microscope to check for abnormal shapes or sizes.
• Bone marrow aspiration and biopsy. In this procedure, the doctor inserts a needle into a large bone, usually the hip, and removes a small amount of bone marrow to examine it for abnormal cells.
• Imaging studies. These may include an X-ray, CT scan, MRI, or ultrasound to check for an enlarged spleen or liver. These imaging studies are used to determine whether a mass of leukemia cells may be in the chest and may potentially interfere with breathing and/or blood circulation, and also to rule out any other possible causes of a child's symptoms.
• Lumbar puncture. Also called a spinal tap, this procedure uses a hollow needle to remove a small amount of cerebrospinal fluid (the fluid surrounding the brain and spinal cord) for examination in a lab. Cancerous WBCs can collect in this area.
• Flow cytometry tests. By analyzing the properties of the cancer cells, doctors can determine the type and many subtypes of leukemia a child has. This is important because treatment varies among different types of leukemia.
• Chromosomal tests. By analyzing DNA from your child's blood or bone marrow, doctors can check for the specific genetic changes that identify the various subtypes of ALL. This is important because treatments may vary according to subtype.

Treatment

Most children with ALL are treated with chemotherapy (the use of special drugs to kill cancer cells). What drugs are used and in what combination will depend on which subtype of ALL is present and how aggressive the disease is.

Chemotherapy can be given intravenously as an injection into a muscle or orally in pill form. In intrathecal (IT) chemotherapy, a spinal tap is used to deliver chemotherapy drugs directly to the cerebrospinal fluid, where cancerous WBCs can collect.

After treatment begins, the goal is remission (when there is no longer evidence of cancer cells in the body). Once remission has occurred, chemotherapy is usually used to keep the child in remission.

Maintenance chemotherapy is given in cycles over a period of 2 to 3 years to keep the cancer from recurring. Leukemia will almost always relapse (recur) if this additional chemotherapy isn't given. Sometimes the cancer will return in spite of maintenance chemotherapy, and other forms of chemotherapy will be necessary.

Some more aggressive forms of ALL might require a stem cell transplant (sometimes called a bone marrow transplant). This procedure involves destroying cancer cells and normal bone marrow and immune system cells with high-dose chemotherapy and then re-introducing healthy donor stem cells into the body. The new stem cells can rebuild a healthy blood supply and immune system.

If a child needs a stem cell transplant, a test (called tissue typing or HLA [human leukocyte antigen] typing) will be done to help doctors find a suitable stem cell donor. This works by comparing the proteins on the surface of a 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 chance that the transplant will be successful.

Coping

Being told that a child has cancer can be a terrifying experience, and the stress of cancer treatment can be overwhelming for any family.

Although you might feel like it at times, you're not alone. To find out about support that may be available to you or your child, talk to your doctor or a hospital social worker. Many resources are available that can help you get through this difficult time.

Reviewed by: Christopher N. Frantz, MD
Date reviewed: October 2012