High-dose Chemotherapy and Stem Cell Transplant for Brain Tumors in Children

High-dose chemotherapy with a stem cell transplant has been tried in clinical trials to treat children and teens with embryonal brain tumors (such as medulloblastoma and pineoblastoma), atypical teratoid/rhabdoid tumors (ATRT), as well as germ cell tumors of the brain (germinomas).

Stem cell transplant may be used to treat brain tumors in infants or very young children. It may also be considered if a tumor, such as those listed above, returns after initial therapy.

When is a stem cell transplant needed?

For cancers that are difficult to treat, higher doses of chemo might be needed. But these higher doses can permanently damage the young blood-forming stem cells. When high doses of chemo are needed as part of treatment, a stem cell transplant (SCT) allows blood stem cells to be saved (harvested) before high-dose chemo is given. These blood stem cells are given back to the child after high-dose chemo is done to replace the blood and allow the marrow to regrow.

SCT is a complex treatment that can cause life-threatening side effects. If the doctors think your child can benefit from a transplant, it’s best to have it done 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 and young adults with brain tumors where a SCT is being considered, their own stem cells are collected and used for the transplant. This is called an autologous SCT.

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 for collection.

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

A central venous catheter is placed so the stem cells can be collected. The collection process (called apheresis) is like donating blood, but instead of going into a collecting bag, the blood goes into a 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 or teen will need to lie flat and hold still during the procedure. This process may be repeated over a few days. The collected stem cells are frozen and saved until they are needed for the transplant.

The high-dose chemo and transplant procedure

Typically, your child will be admitted to the SCT unit of the hospital the day before the high-dose chemo begins. During the transplant and recovery, children usually stay in the hospital for several weeks or more, until the stem cells have started making new blood cells again.

High-dose chemo is given 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 start making new red blood cells and platelets. Until new blood cells are made, the risk of infection and bleeding is high. To help lower the risk of infection, you or your child will be in a special hospital room. Visitors will be limited and must wear protective clothing. Blood and platelet transfusions will be given as needed while the bone marrow recovers. Antibiotics to treat infections may be needed while the body heals.

The child or teen will stay in the hospital until the infection-fighting white blood cells rise to safe levels. Even after discharge from the hospital, care in an outpatient clinic is often needed almost every day for several weeks. Your transplant team will decide when it is safe to return to your regular doctors.

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 result from damage to the bone marrow and other quickly growing tissues of the body, and can include:

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

One of the most common complications of transplant is an increased risk of serious infections. Antibiotics are often given to help prevent this. Other side effects, such as 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, lungs, or kidneys
• Problems with the thyroid or other hormone-making glands
• Problems with fertility
• Damage to bones or problems with bone growth
• Development of another cancer years later

Be sure to talk to your cancer care team before the transplant to learn about possible long-term effects your child might have.