Childhood Leukemia

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Treating Leukemia in Children TOPICS

High-dose chemotherapy and stem cell transplant for childhood leukemia

A stem cell transplant (SCT) can sometimes be used for children whose chances of being cured are poor with standard or even intensive chemotherapy. SCT lets doctors use even higher doses of chemotherapy than would normally be tolerated.

High-dose chemotherapy destroys the bone marrow, which is where new blood cells are formed. This could lead to life-threatening infections, bleeding, and other problems caused by low blood cell counts. A stem cell transplant is given after the chemo to restore the blood-forming stem cells in the bone marrow.

The stem cells used for a transplant come either from the blood (for a peripheral blood stem cell transplant [PBSCT] or an umbilical cord blood transplant) or from the bone marrow (for a bone marrow transplant, or BMT). Bone marrow transplants were more common in the past, but they have largely been replaced by PBSCT and cord blood transplants.

Types of transplants

The 2 main types of stem cell transplants are allogeneic and autologous.

Allogeneic stem cell transplant: For childhood leukemia, the blood-forming stem cells are donated from another person. This is called an allogeneic transplant.

The donor’s tissue type (also known as the HLA type) should match the patient’s tissue type as closely as possible to help prevent the risk of major problems with the transplant. Tissue type is based on certain substances on the surface of cells in the body. These substances can cause the immune system to react against the cells. Therefore, the closer the tissue match between the donor and the recipient, the better the chance the transplanted cells will “take” and begin making new blood cells.

The donor is usually a brother or sister with the same tissue type as the patient. Rarely, it can be an HLA-matched, unrelated donor – a stranger who has volunteered to donate blood-forming stem cells. Sometimes umbilical cord stem cells are used. These stem cells come from blood drained from the umbilical cord and placenta after a baby is born and the umbilical cord is cut. (This blood is rich in stem cells.) Whatever their source, the stem cells are then frozen and stored until they are needed for the transplant.

Autologous stem cell transplant: In an autologous transplant, the patient’s own stem cells are removed from his or her bone marrow (bone marrow stem cells) or bloodstream (peripheral blood stem cells, PBSCs). This type of transplant is not used for childhood leukemia, because the risk that the leukemia will come back (relapse) after treatment is greater than with an allogeneic transplant.

When stem cell transplant (SCT) might be used

SCT might be used for a child with ALL whose leukemia doesn’t respond well to initial treatment or relapses early after going into remission. It is less clear if SCT should be used for children whose ALL relapses more than 6 months after finishing the initial chemotherapy. These children will often do well with another round of standard dose chemotherapy. SCT may also be recommended for children with some less common forms of ALL, such as those whose leukemias have the Philadelphia chromosome or those with T-cell ALL that doesn’t respond well to initial treatment.

Because AML relapses more often than ALL, many doctors recommend SCT for children with AML right after they have gone into remission, if the child has a brother or sister with the same tissue type who can donate stem cells for the transplant. This is especially true if there is a very high risk of relapse (as seen with some subtypes of AML or when there are certain chromosome changes in the cells). There is still some debate about which children with AML need this type of intensive treatment. If a child with AML relapses after his or her first round of standard chemotherapy, most doctors will recommend SCT as soon as the child goes into remission again. In either case, it is important that the leukemia is in remission before getting a stem cell transplant. Otherwise, the leukemia is more likely to return.

SCT might also offer the best chance to cure some less common types of childhood leukemia, such as juvenile myelomonocytic leukemia (JMML) and CML. For CML, newer targeted therapies are likely to be used first for most children, but a transplant might still be needed at some point.

How a stem cell transplant (SCT) is done

A stem cell transplant is a complex treatment that can cause life-threatening side effects. If the doctors think your child can benefit from a transplant, the best place to have this done is at a nationally recognized cancer center where the staff has experience with the procedure and with managing the recovery period.

Typically, the child is admitted to the stem cell transplant unit of the hospital on the day before the treatment begins. He or she will usually stay in the hospital until after the chemo and the stem cells have been given, and until the stem cells have started making new blood cells again (see below).

The child gets high-dose chemotherapy and sometimes radiation treatment to the entire body. (Radiation shields are used to protect the lungs, heart, and kidneys from damage during radiation therapy.) These treatments are meant to destroy any remaining leukemia cells. But they also kill the normal cells in the bone marrow.

After treatment, the frozen stem cells are thawed and given as a blood transfusion. The stem cells settle into the child’s bone marrow over the next several days. Usually within a couple of weeks, they begin making new white blood cells. This is later followed by new platelet and red blood cell production.

In the meantime, the child is at high risk for serious infections because of a low white blood cell count, as well as bleeding because of a low platelet count. During this time, blood and platelet transfusions and treatment with IV antibiotics are often used to help prevent or treat infections or bleeding problems.

Because of the high risk of serious infections right after treatment, patients usually stay in the hospital in protective isolation (guarding against exposure to germs) until part of their white blood cell count (known as the absolute neutrophil count, or ANC) rises above 500. They may be able to leave the hospital when their ANC is near 1,000.

The child is then seen in an outpatient clinic almost every day for several weeks. Because platelet counts take longer to return to a safe level, they may get platelet transfusions as an outpatient. Patients may make regular visits to the outpatient clinic for about 6 months, after which time their care may be continued by their regular doctors.

A stem cell transplant often requires a long hospital stay and can be very expensive (often costing well over $100,000). Be sure to get a written approval from your insurer before treatment if it is recommended for your child. Even if the transplant is covered by your insurance, your co-pays or other costs could easily amount to many thousands of dollars. It’s important to find out what your insurer will cover before the transplant to get an idea of what you might have to pay.

Possible side effects of stem cell transplant (SCT)

The possible side effects from SCT are generally divided into short and long-term effects.

Short-term side effects

The early complications and side effects are basically those caused by high-dose chemotherapy (see the “Chemotherapy” section of this document) and can be severe. They can include:

  • Low blood cell counts (with fatigue and an increased risk of infection and bleeding)
  • Nausea and vomiting
  • Loss of appetite
  • Mouth sores
  • Diarrhea
  • Hair loss

One of the most common and serious short-term effects is the increased risk of serious infections. Antibiotics are often given to try to prevent this from happening. Other side effects, like low red blood cell and platelet counts, may require blood product transfusions or other treatments.

Long-term and late side effects

Some complications and side effects can last for a long time or may not occur until months or years after the transplant. These can include:

  • Graft-versus-host disease (see below)
  • Radiation damage to the lungs
  • Problems with the thyroid or other hormone-making glands
  • Problems with fertility
  • Damage to bones or problems with bone growth
  • Development of another cancer (including leukemia) years later

Graft-versus-host disease (GVHD) is one of the most serious complications of allogeneic (donor) stem cell transplants. This happens when the donor immune system cells attack tissues of the patient’s own cells.

The areas most often affected include the skin, liver, and digestive tract, but other areas may be affected as well. GVHD can be acute or chronic, based on how soon after the transplant it begins. In severe cases, GVHD can be life-threatening. Drugs that weaken the immune system are often given as a part of the transplant to try to prevent GVHD, although they can have their own side effects.

The most common symptoms of GVHD are severe skin rashes and severe diarrhea. If the liver is affected, the damage can lead to jaundice (yellowing of the skin and eyes) or even liver failure. GVHD can also cause lung damage, leading to problems breathing. The patient may feel weak, become tired easily, and have nausea, dry mouth, and muscle aches.

On the good side, graft-versus-host disease can lead to graft-versus-leukemia activity, in which any remaining leukemia cells may be killed by the donor immune cells.

Be sure to talk to your child’s doctor before the transplant to learn about possible long-term effects your child might have. More information on long-term effects can be found in the section, “What happens after treatment for childhood leukemia?

To learn more about stem cell transplants, see our document, Stem Cell Transplant (Peripheral Blood, Bone Marrow, and Cord Blood Transplants).

Last Medical Review: 10/24/2013
Last Revised: 02/03/2014