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What Is Leukemia?

Leukemia is cancer of the white blood cells. White blood cells (also called leukocytes or WBCs) fight infections and other diseases.

In leukemia, the bone marrow (spongy material inside the bones) makes many white blood cells that aren't normal. These abnormal WBCs crowd the bone marrow and get into the bloodstream. Unlike healthy white blood cells, they can't protect the body from infections.

Sometimes leukemia (loo-KEE-mee-uh) spreads from the bone marrow to other parts of the body, like the chest, brain, or liver.

Leukemia is the most common type of cancer in children. But most kids and teens treated for leukemia are cured of the disease.

What Are the Types of Leukemia?

Most cases of leukemia in children are:

Less common types of childhood leukemia include:

What Are the Signs & Symptoms of Leukemia?

Kids with leukemia may get more viral or bacterial infections than other kids. These happen because their white blood cells can't fight infections.

They also may get anemia, which is when there's a low number of red blood cells. This happens because leukemia cells crowd the bone marrow. This prevents bone marrow from making the usual amount of oxygen-carrying red blood cells.

Kids with anemia may:

  • look pale
  • feel very tired, weak, or short of breath while playing
  • bruise very easily, get a lot of 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 with no other symptoms
  • belly pain

Sometimes leukemia can spread, or metastasize. 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 Leukemia?

Doctors don't know exactly what causes leukemia. But most cases happen when there is a change (mutation) in a gene that happens spontaneously. This means that the genetic mutation was not passed down from a parent.

Kids have a greater chance of developing leukemia if they have:

  • an identical twin who had leukemia at a young age
  • a non-identical twin or other siblings with leukemia
  • had radiation therapy or chemotherapy for other types of cancer
  • taken medicines to suppress their immune system after an organ transplant 
  • a genetic health problem, such as:
    • Li-Fraumeni syndrome
    • Down syndrome
    • Klinefelter syndrome
    • neurofibromatosis
    • ataxia telangectasia
    • Fanconi anemia

Leukemia affects adults and children. It is more common in boys than girls. The different types of leukemia affect different age groups:

  • ALL is most common in children 2 to 8 years old.
  • AML can happen at any age, but most cases happen in kids younger than 2 and teens.
  • CML is most common in teens.
  • JMML affects infants and toddlers.

How Is Leukemia Diagnosed?

To find out if a child has leukemia, a doctor will:

  • Ask questions about the symptoms.
  • Do an exam to check for signs of infection, anemia, unusual bleeding, and swollen .
  • Feel the child's belly to check the liver and spleen because leukemia can make these organs get bigger.

The doctor also will order some blood tests. Depending on the results, other testing done can include:

How Is Leukemia Treated?

A pediatric oncologist (a doctor who treats childhood cancer) will lead the medical team caring for a child with leukemia. The oncologist works with other specialists, including nurses, social workers, psychologists, and surgeons.

Chemotherapy is the main treatment for childhood leukemia. The dosages and drugs used may differ based on the child's age and the type of leukemia.

Other treatments include:

  • radiation therapy: high-energy X-rays that kill cancer cells
  • targeted therapy: specific drugs that find and attack cancer cells without hurting normal cells
  • stem cell transplants: putting healthy stem cells into the body

What Else Should I Know?

With the right treatment, the outlook for kids and teens with leukemia is quite good.

Most childhood leukemias have very high remission rates, with some up to 90%. Remission means that doctors see no cancer cells in the body. Most kids are cured of the disease. This means that they're in permanent remission.

Having a child being treated for cancer can be a challenge for any family. But you're not alone. To find support, talk to anyone on the care team or a hospital social worker. Many resources are available to help you and your child.

You also can find information and support online at:

Medically reviewed by: Jonathan L. Powell, MD
Date reviewed: April 2024