Chemotherapy for Ewing tumors

Chemotherapy (chemo) is the use of anti-cancer drugs delivered through a vein or, rarely, by mouth in the form of pills. These drugs enter the bloodstream and reach all areas of the body.

The section called "How are Ewing tumors staged?" notes that patients with localized Ewing tumors have no obvious cancer spread in bone marrow specimens or on imaging tests. Still, many of these patients have areas of cancer spread that are too small to be seen with these tests. If these patients do not get chemotherapy, these small metastases would eventually develop into larger tumors.

This is why chemotherapy is part of treatment for just about all patients with Ewing tumors. It is typically the first treatment given, followed by surgery and/or radiation therapy. Chemotherapy is often then given again.

A combination of several chemo drugs is used to treat patients with Ewing tumors. In the United States, the most common regimen is to alternate between 2 combinations of drugs given every 2 to 3 weeks (known as the VAC/IE regimen). The first set of drugs includes vincristine, doxorubicin (Adriamycin), and cyclophosphamide. After the patient recovers from the effects of these drugs, another combination of drugs, ifosfamide and etoposide, is given. Some doctors may use slightly different combinations of drugs.

Chemotherapy is given for at least 12 to 24 weeks before surgery or radiation to the tumor and is then given afterward as well (usually for a total of 14 to 15 cycles). If the tumor has spread, these same drugs may be given at higher doses.

Soon after the Ewing tumor is diagnosed (and before starting chemotherapy), the doctor may suggest inserting a venous access device into a large vein in the patient’s chest. The device is a catheter (hollow tube) that is inserted surgically while the patient is under general anesthesia (asleep). One end of the catheter stays in the vein, while the other end lies just under or outside the skin. This allows the health care team to give chemo and other drugs into the blood system and to draw blood samples without having to stick needles into the veins each time. The device can usually remain in place for several months, and can make having chemotherapy much less painful for the patient. If such a device is used in your child, the health care team will teach you how to care for it to reduce the risk of problems such as infections.

Possible side effects of chemotherapy

Chemo drugs attack cells that are dividing quickly, which is why they work against cancer cells. But other cells in the body, such as those in the bone marrow, the lining of the mouth and intestines, and the hair follicles, also divide quickly. These cells are also likely to be affected by chemotherapy, which can lead to side effects.

Children seem to have an advantage over adults when it comes to chemotherapy. They tend to have less severe side effects and recover from side effects more quickly. This is why doctors can often give them higher doses of chemotherapy to kill the tumor.

The side effects of chemotherapy depend on the type and dose of drugs given and the length of time they are taken.

General side effects: General side effects of chemo drugs can include:

• Hair loss
• Mouth sores
• Loss of appetite
• Nausea and vomiting
• Diarrhea
• Increased chance of infections (due to low white blood cell counts)
• Easy bruising or bleeding (due to low blood platelet counts)
• Fatigue (due to low red blood cell counts)

Most of these side effects are short-term and tend to go away after treatment is finished. There are often ways to lessen these side effects. For example, drugs can be given to help prevent or reduce nausea and vomiting, or to help get blood counts back to normal levels. Be sure to discuss any questions you have about side effects with the cancer care team.

Side effects of certain drugs: Along with the effects listed above, certain chemo drugs can have specific side effects.

Cyclophosphamide and ifosfamide can damage the bladder, which can cause blood in the urine. The chance of this happening can be lowered by giving the drugs with plenty of fluids and with a drug called mesna, which helps protect the bladder. These drugs can also damage the ovaries or testicles, which might affect fertility (the ability to have children).

Doxorubicin can cause heart damage. The risk of this happening goes up as the total amount of the drug that is given goes up. Doctors try to reduce this risk as much as possible by not giving more than the recommended doses of doxorubicin and by checking the heart with a test called an echocardiogram during treatment.

Vincristine can damage nerves. Some patients may notice tingling and numbness, particularly in the hands and feet.

Some drugs used to treat Ewing tumors, such as etoposide, can increase the risk of later developing a cancer of white blood cells known as acute myeloid leukemia. Fortunately, this doesn't happen often.

Long-term side effects: Some side effects may not go away or may not happen until years after treatment is finished. Examples include:

• Infertility (being unable to have children)
• Heart damage
• Developing a second cancer

Some of these long-term effects are described in the section called "What happens after treatment for Ewing tumors?"

Tests to check for side effects of chemotherapy: Before each chemotherapy treatment, your (child's) doctor will check lab test results to be sure the liver, kidney, and bone marrow are functioning well. If not, chemotherapy may need to be delayed or the doses reduced.

The complete blood count (CBC) includes counts of white blood cells, red blood cells, and blood platelets. Chemotherapy can lower the numbers of these blood cells, so blood counts will be watched closely during and after chemotherapy. The cells usually reach their lowest point about 2 weeks after chemo is given, though this can occur earlier with high-dose regimens.

Blood chemistry tests measure certain blood chemicals that tell doctors how well the liver and the kidneys are working. Some chemo drugs can damage the kidneys and liver.

If doxorubicin (Adriamycin) is to be given, tests such as an echocardiogram (an ultrasound of the heart) may be done to check heart function before and during treatment.

For more information on chemotherapy, see our document called Understanding Chemotherapy: A Guide for Patients and Families.