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This type of treatment is being studied for Ewing tumors (Ewing sarcomas) that are hard to cure with other treatments, such as tumors that have spread (metastasized) to other parts of the body or that have come back after standard treatment. So far, it's not clear if a stem cell transplant is better than other treatments (such as standard chemotherapy), so most doctors recommend it be done only as part of a clinical trial.

What is a stem cell transplant?

The doses of chemotherapy (chemo) drugs that can be given safely are normally limited by the side effects these drugs can cause. One of the most serious is damage to the stem cells in bone marrow, which make new blood cells. Even though higher doses of chemo might be more effective in treating Ewing tumors, they can’t be given because they would severely damage these bone marrow cells, leading to life-threatening shortages of blood cells.

To try to get around this problem, high-dose chemo (sometimes along with radiation therapy) can be followed by a stem cell transplant to “rescue” the bone marrow, giving the person new blood stem cells to replace those that were destroyed.

In the past, this type of treatment was often called a bone marrow transplant.

If a stem cell transplant is considered as part of the initial treatment plan for a Ewing tumor, the person first gets standard doses of chemo, then local treatment of the tumor (surgery and/or radiation therapy), followed by high-dose chemo and a stem cell transplant.

How a stem cell transplant is done

The first step in a stem cell transplant is done before the treatment with high-dose chemo. The patient's own blood-producing stem cells are collected (harvested) to use later. This type of transplant, where the stem cells are taken from the patient, is known as an autologous transplant. (In another type of stem cell transplant, called an allogeneic transplant, the stem cells come from a donor. This type is not used often for treating Ewing tumors.)

The stem cells are usually collected from the blood using a procedure similar to a blood donation. 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. Stem cells might need to be collected more than once.

Once the stem cells have been frozen and stored, the person gets high-dose chemo, sometimes along with radiation therapy. When the treatment is finished, the patient’s stem cells are thawed and returned to the body in a blood transfusion. The stem cells travel through the bloodstream and settle in the bone marrow. Over the next few weeks, they start to make new, healthy blood cells.

Side effects of stem cell transplants

A stem cell transplant is a complex treatment that can cause serious or even life-threatening side effects. If the doctors think a person might benefit from a transplant, it should be done at a cancer center where the staff has experience in doing the procedure and managing the recovery period.

The main side effects from a stem cell transplant are from the chemotherapy. Because high doses of chemo are used, some of these side effects might be more severe than with standard doses of chemo.

Some side effects of a stem cell transplant might last a long time, or they might not show up until years after the transplant, which is a special concern in children and teens. If a stem cell transplant is recommended for your child, be sure to talk to the cancer care team before the transplant to learn about possible long-term effects your child might have.