High-dose chemotherapy and stem cell transplant for Ewing tumors

This type of treatment is being studied for use in patients with Ewing tumors that are unlikely to be cured with other treatments, such as patients with metastatic disease or those whose disease comes back after the standard treatment. It involves giving very high doses of chemotherapy, and then replacing the body's bone marrow cells, which were killed by the treatment. When this approach is used, the patient receives the standard chemotherapy first, and then receives high-dose chemotherapy and a stem cell transplant.

In the past, this type of treatment was commonly referred to as a bone marrow transplant. The bone marrow is the soft inner part of some bones where new red blood cells, white blood cells, and platelets are made. Red blood cells carry oxygen to all parts of the body. White blood cells help the body fight infections. Platelets are needed to help the blood clot to stop bleeding.

The usual doses of chemotherapy drugs can affect quickly dividing cells like those in the bone marrow. Even though higher doses of these drugs might be more effective in treating tumors, they can't be given because they would severely damage bone marrow cells, leading to life-threatening shortages of blood cells.

To try to get around this problem, a doctor may treat the child with high-dose chemotherapy and then give a peripheral blood stem cell transplant (PBSCT) to "rescue" the bone marrow.

What happens in a peripheral blood stem cell transplant

The first step in a PBSCT is to collect, or harvest, the child's own blood-producing stem cells to use later. (These are the cells that make the different types of blood cells.) This type of transplant, where the stem cells are taken from the patient (as opposed to coming from someone else), is known as an autologous transplant.

In the past, the stem cells were often taken from the child's bone marrow, which required a minor operation. But doctors have found that these cells can be taken from the bloodstream using a procedure known as apheresis. This 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 to the person's body. The stem cells are then frozen until the transplant. This may need to be done more than once.

Once the stem cells have been stored, the child gets high-dose chemotherapy, sometimes along with radiation therapy. When the treatment is finished, the patient's stem cells are thawed and returned to the body in a process similar to a normal blood transfusion. The stem cells travel through the bloodstream and settle in the bone marrow. Over the next 3 or 4 weeks, they start to make new, healthy blood cells.

Until this happens, 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 avoid infection, protective measures are taken, such as using special air filters in the hospital room and having visitors wear protective clothing. Blood and platelet transfusions and treatment with IV antibiotics may also be used to prevent or treat infections or bleeding problems.

Practical points

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

A stem cell transplant often requires a long hospital stay and can be very expensive (often costing well over $100,000). Because the procedure is so expensive, you should 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 is 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

Possible early complications and side effects are basically the same as those caused by any other type of high-dose chemotherapy (see the "Chemotherapy" section of this document), and can be severe. They are caused by damage to the bone marrow and other quickly dividing tissues of the body, and 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 an increased risk of infection. Antibiotics are often given to try to keep this from happening. Other side effects, like low red blood cell and platelet counts, may require blood product transfusions or other treatments.

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

• 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

Be sure to talk to your child's doctor before the transplant to learn about possible long-term effects your child may have.

For more information on stem cell transplants, see our document called Stem Cell Transplant (Peripheral Blood, Bone Marrow, and Cord Blood Transplants).