Chemotherapy for childhood leukemia

Chemotherapy (chemo) is treatment with anti-cancer drugs that are given into a vein, into a muscle, into the cerebrospinal fluid (CSF), or taken by mouth as pills. Except when given into the CSF, these drugs enter the bloodstream and reach all areas of the body, making this treatment useful for cancers such as leukemia.

The treatment of leukemia uses combinations of several anti-cancer drugs. Doctors give chemo in cycles, with each period of treatment followed by a rest period to allow the body time to recover. In general, treatment for acute myeloid leukemia (AML) uses higher doses of chemo over a shorter period of time, and acute lymphocytic leukemia (ALL) treatment uses lower doses of chemo over a longer period of time (usually 2 to 3 years).

Some of the drugs commonly used to treat childhood leukemia include:

• Vincristine (Oncovin)
• Daunorubicin, also known as daunomycin (Cerubidine)
• Doxorubicin (Adriamycin)
• Cytarabine, also known as cytosine arabinoside or ara-C (Cytosar)
• L-asparaginase (Elspar), PEG-L-asparaginase (pegaspargase, Oncaspar)
• Etoposide (VePesid, others)
• Teniposide (Vumon)
• 6-mercaptopurine (Purinethol)
• 6-thioguanine
• Methotrexate
• Mitoxantrone
• Cyclophosphamide (Cytoxan)
• Prednisone (numerous brand names)
• Dexamethasone (Decadron, others)

Children will probably get several of these drugs at different times during the course of treatment, but they do not get all of them.

Possible side effects of chemotherapy

Chemotherapy 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 (where new blood cells are made), 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.

The side effects of chemo depend on the type and dose of drugs given and the length of time they are taken. These side effects may include:

• Hair loss
• Mouth sores
• Loss of appetite
• Diarrhea
• Nausea and vomiting
• Increased risk of infections (because of low white blood cell counts)
• Bruising and bleeding easily (from low platelet counts)
• Fatigue (caused by low red blood cell counts)

The problems with blood cell counts are often caused by the leukemia itself at first. They might get worse during the first part of treatment because of the chemotherapy, but they will probably improve as the normal cells recover and the leukemia cells are killed off.

The side effects listed above are usually short-term and go away when treatment is finished. There are often ways to reduce these side effects. For instance, drugs can be given along with the chemotherapy to help prevent or reduce nausea and vomiting. Other drugs known as growth factors can be given to help keep the blood cell counts higher.

Tumor lysis syndrome is another possible side effect of chemotherapy. It can be seen in patients who had large numbers of leukemia cells in the body before treatment. When chemo kills these cells, they break open and release their contents into the bloodstream. This can overwhelm the kidneys, which aren't able to get rid of all of these substances at once. Excess amounts of certain minerals may also affect the heart and nervous system. This can be prevented by making sure the child gets lots of fluids during treatment and by giving certain drugs, such as bicarbonate, allopurinol, and rasburicase, which help the body get rid of these substances.

Some chemo drugs can also have specific side effects that are not listed above. Be sure to ask your child's doctor or nurse about any specific side effects you should watch for and about what you can do to help reduce these side effects.

Chemotherapy given directly into the cerebrospinal fluid (CSF) around the brain and spinal cord can have its own side effects, although these are not common. Chemo may cause trouble thinking or even seizures in some children.

Long-term side effects of chemotherapy are also possible. These are discussed in the section, "What happens after treatment for childhood leukemia?"