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This type of treatment combines higher doses of chemotherapy (chemo) with a transplant to replace the bone marrow stem cells damaged by the chemo. It is often used in children with high-risk neuroblastoma who are unlikely to be cured with other treatments.

Giving higher doses of chemotherapy might be more effective in treating these cancers, but normally this can’t be done because it would cause severe damage to the stem cells in the bone marrow, which make new blood cells. This could lead to life-threatening shortages of blood cells.

A stem cell transplant (SCT) can sometimes help doctors get around this problem by giving the high-dose chemo, then replacing the patient’s bone marrow cells by giving them new stem cells.

Before the stem cell transplant, a child is usually given about 5 months of intense chemotherapy and sometimes surgery to remove the tumor as well. Some children might get 2 stem cell transplants a few months apart, called tandem stem cell transplants.

SCT 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 cancer center where the staff has experience with the procedure and managing the recovery period.

Collecting stem cells before the transplant

For most children with neuroblastoma, their own stem cells are collected and used for the transplant.

To help prepare for stem cell collection, doctors give a medicine called G-CSF (filgrastim),which helps the bone marrow make more stem cells and helps those cells move into the bloodstream.

G-CSF is usually started at the end of a regular cycle of chemo and is given daily. Once part of the white blood cell count (known as the absolute neutrophil count, or ANC) reaches a certain level, the dose of G-CSF is increased until there are enough stem cells to collect.

The child will have a special kind of central venous catheter put in place so the stem cells can be collected during a process called apheresis. The collection process is similar to donating blood, but instead of going into a collecting bag, the blood goes into a special machine that filters out the stem cells and returns the other parts of the blood back to the child’s body. Apheresis can take a few hours, and your child will probably need to lie flat and hold still during the procedure. This process may be repeated over a few days. The collected stem cells are then frozen until the transplant.

The high-dose chemo and transplant procedure

Typically, the child will be admitted to the SCT unit of the hospital on the day before the high-dose chemo begins. They 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 (typically at least several weeks).

The child gets high-dose chemo first. This destroys the cancer cells in the body, as well as the normal cells in the bone marrow. After the chemo, the frozen stem cells are thawed and given as a blood transfusion. The stem cells travel through the bloodstream and settle in the child’s bone marrow.

Usually within a couple of weeks, the stem cells begin making new white blood cells. Soon after, they will start making new red blood cells and platelets. Until new blood cells are made, the child is at high risk of infection because of a low white blood cell count, as well as bleeding because of a low platelet count. To help lower the risk of infection, the child stays in a special hospital room, and visitors must wear protective clothing. Blood and platelet transfusions and treatment with IV antibiotics may also be used to help prevent or treat infections or bleeding problems.

The child usually stays in the hospital room until the ANC rises to a safe level. The child is then seen in an outpatient clinic almost every day for several weeks. Because platelet counts often take longer to return to a safe level, the child may get platelet transfusions as an outpatient. Patients may need to make regular visits to the outpatient clinic for about 6 months, after which time their regular doctors may continue their care.

Possible side effects

A stem cell transplant can have both short-term and long-term side effects.

Early or short-term side effects

The early complications and side effects are usually caused by the high-dose chemo, and they can be severe. They are the result of damage to the bone marrow and other quickly growing tissues of the body, and can include:

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

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

Late or long-term side effects

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

• Damage to the heart or 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

Be sure to talk to your child’s doctor before the transplant to learn about possible long-term effects your child might have. For more on the possible long-term effects of this and other treatments, see Late and Long-term Effects of Neuroblastoma and Its Treatment.