Leukemia is a cancer of the blood-forming cells found in bone marrow (the soft center of most long bones in the body). Bone marrow produces blood cells. When a child has leukemia, their bone marrow produces increased numbers of immature and nonfunctioning blood cells called "blasts." These blasts do not mature correctly and can occur in large numbers. Blasts crowd out normal healthy blood cells in the bone marrow.

White blood cells are the most often affected by leukemia. But, other types of blood cells, such as red blood cells or platelets, also can be involved. The effects on the body depend on which blood cells are affected.

• Red blood cells transport oxygen to all parts of the body. A reduced number of these cells may result in anemia, causing fatigue and trouble breathing.
• Platelets stop bleeding by helping to form clots. Low numbers of platelets in the blood can result in too much bleeding or easy bruising.
• White blood cells protect us from infections. Not having enough white blood cells increases the risk of infection.

Because leukemia changes the blood, it affects the whole body.

Types of Leukemia

There are two categories of childhood leukemia: acute or chronic. Acute means that cancer growth is rapid. Chronic cancers grow more slowly.

Acute leukemia is more common in children. Typically, there are three main types of acute leukemia:

• Acute lymphoblastic leukemia, or ALL, is most common in young children between the ages of two and four. ALL occurs more commonly in boys and Hispanic or Caucasian children and less often among African American children.
• Acute myelogenous leukemia, or AML, can develop at any time during childhood, but most often occurs within the first two years of life or during the teenage years. AML affects children equally across genders and races. AML is also known as acute myeloid leukemia, acute myelocytic leukemia, or acute nonlymphocytic leukemia.
• Hybrid or mixed-lineage leukemia is a rare form of leukemia that has characteristics of both ALL and AML.

There are two forms of chronic leukemia:

• Chronic myelogenous leukemia.
• Chronic lymphocytic leukemia.

Chronic leukemias are rare and are seen mostly in older children. You can find information on these less common types of leukemia and other rare childhood cancers at the American Cancer Society's website.

Juvenile myelomonocytic leukemia is another rare but serious type of cancer. It is not described as being either acute or chronic.

Children with leukemia may experience:

• Fever.
• Weight loss.
• Bone pain.
• Bruising or bleeding.
• Weakness and fatigue.
• Swelling or pain in various parts of the body.

As the number of leukemia cells increases in the bone marrow and the number of normal cells that prevent anemia, bleeding, and infections decrease, children may become weak, experience fatigue, develop infections, and generally not feel well. Increased bleeding may cause symptoms to occur, such as:

• Bruises.
• Nosebleeds.
• Bleeding gums.
• Paleness.

If the leukemia cells enter other organs of the body, swelling and pain might occur in those organs. Bone pain may cause a child to refuse or avoid walking or standing. Children typically enjoy activities and play. If your child experiences any of these symptoms and limits their play, they should see their doctor. Other illnesses have symptoms similar to those of leukemia, and your child's doctor can conduct tests to make a correct diagnosis.

When a child or teenager shows symptoms related to leukemia, they should receive a physical exam and a full review of their medical history by a health care provider. Parents should report:

• Any symptoms they have noticed.
• How long the symptoms have been present.
• Risk factors, such as genetic factors or prior treatment with chemotherapy or radiation.
• Whether there is a family history of cancer.

Tests used to diagnose leukemia include:

• Blood tests.
• Bone marrow tests.
• Spinal fluid tests.

The blood test determines the number of each type of blood cell present (called a complete blood count) and their appearance under a microscope. When leukemia is present, the number of abnormal, immature white blood cells or blasts is higher, and the red blood cell count is lower than normal.

Bone marrow and spinal fluid tests help to classify the type of leukemia and to gather information about the specific genetic makeup of the abnormal cells.

These tests may be repeated during treatment to determine how well the child is responding to cancer treatments.

The physical therapist is an important member of a team of health care professionals who work with children who have leukemia. Physical therapy for children with leukemia should begin at the time of diagnosis. The goals of physical therapy treatment for all these children are to:

• Reduce pain.
• Maintain strength and movement.
• Maximize the child's ability to take part in activities during treatment.
• Support as much participation as possible in activities during chemotherapy or other treatments.
• Monitor functional abilities to prevent loss of function during treatment.

The most common medical treatment for leukemia is chemotherapy — the use of drugs to kill cancer-causing cells. Chemotherapy often involves a combination of several different medicines. It can be given in a variety of ways, including through a vein or in pill form. Chemotherapy regimens for the ALL type of leukemia usually take about two to three years. The regimens for the AML type of leukemia take about one year.

Many children receive vincristine as part of their chemotherapy plan. Vincristine can cause chemotherapy-induced peripheral neuropathy, an adverse effect that damages a child's nerves, especially those in the hands and feet. Peripheral neuropathy can result in:

• Loss of sensation.
• Muscle weakness.
• Difficulty with walking and going up and down stairs.
• Problems with "fine motor" skills, such as opening bottles and tying shoes.

Physical therapists can help children better manage these side effects with exercise, gait (walking) training, and the use of assistive devices, such as walkers and devices that support the ankle.

Another possible medical treatment for leukemia is a stem-cell transplant, or SCT. This procedure involves transplanting stem cells acquired from a sibling, an unrelated donor, or possibly from umbilical cord blood into the child with leukemia. STC replaces stem cells damaged by cancer with stem cells that function normally, producing healthy, normal blood cells.

Children who receive chemotherapy or SCT may experience other side effects, including:

• Nausea.
• Vomiting.
• Hair loss.
• Mouth sores.
• Decreased blood counts.
• Changes in sensation, particularly in the feet.
• Muscle weakness.
• Fatigue.

The lengthy treatment also may result in weakness and a loss of the ability to participate in activities like other children. Physical therapists apply strategies to modify play and learning activities, and encourage children to take part in fun activities that promote their normal growth and development during treatment.

The exact cause of leukemia is not known. Risk factors include both genetics and the child's environment. Syndromes, such as Down syndrome and Li-Fraumeni syndrome, and genetic disorders, such as neurofibromatosis and Fanconi anemia, increase a child's risk of developing leukemia. Inherited immune-system conditions also increase the risk of leukemia. Siblings of a child diagnosed with leukemia have a slightly increased risk of developing the disease.

Environmental factors that can increase a child's risk of developing leukemia include exposure to:

• Chemotherapy.
• Radiation, including prenatal radiographs.
• Certain chemicals.

Children and adults who received treatment for another type of cancer with certain chemotherapy agents are at an increased risk of developing a second cancer.

All physical therapists are prepared through education and experience to treat children with leukemia. However, you may want to consider:

• A physical therapist who is a board-certified clinical specialist in either pediatrics or oncology. These physical therapists have completed a residency or fellowship in pediatrics or oncology. These specialists may identify themselves by the words "pediatric certified specialist" or "oncology certified specialist."
• A physical therapist who has experience working in a pediatric oncology setting or who has a practice specializing in pediatric oncology.

You can find physical therapists who have these and other credentials by using Find a PT, an online tool built by the American Physical Therapy Association to help you search for physical therapists with specific clinical expertise and located in your geographic area. Any physical therapist you select will be able to work with your child's medical team in many different settings, including the clinic, home, school, and community.

General tips when you are looking for a physical therapist (or any other health care provider):

• Get recommendations from family, friends, or other health care providers.
• When you contact a physical therapy clinic or home health agency for an appointment, ask about the physical therapists' experience in helping children with cancer.
• Be prepared to describe your child's symptoms and movement activities in as much detail as possible, and to discuss your goals for your child.

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