A variety of drugs are used to treat leukemia. Currently the standard drugs include vincristine, prednisone, l-asparaginase. Methotrexate, 6-MP, cytosine, arabinoside. Other drugs that may be used include daunorubicin, doxorubicin, etoposide, purine, and cyclophosphamide. The severity of side effects depends on the type of drug, the dose given, and the length of time the child must take it. Patients with leukemia are often treated with induction therapy, in which several rounds of chemotherapy are given until the disease is in remission. After a few weeks in remission, a second phase of chemotherapy, called consolidation therapy, is started to kill any remaining cancer cells and prevent a relapse.

Because chemotherapy attacks rapidly dividing cells, including those in normal tissues such as the hair, lining of the mouth and intestines and bone marrow, patients may experience hair loss, mouth sores, nausea and vomiting. In addition, most chemotherapy drugs are myelosuppressive - they lower the body's production of blood cells and platelets. This results in lowered resistance to infections due to low white blood cell counts or bruising and bleeding more easily due to lowered platelet counts. Low red blood cell counts (anemia) may cause fatigue. These conditions go away after chemotherapy is completed.

To lessen the side effects during chemotherapy treatment, the doctor may prescribe other drugs to reduce nausea and vomiting. Agents called growth factors can elevate white blood cell counts, lowering the child's risk of infection, and red blood cell counts, alleviating fatigue.

Chemotherapy causes the rapid breakdown of leukemia cells, resulting in the release of by-products into the bloodstream. These by-products can damage the heart, kidneys and nervous system. However, this condition can also be prevented with special drugs (bicarbonate and allopurinol) and by drinking extra fluids.

Taking chemotherapy drugs called epipodophylotoxins and alkylating agents raises a child's risk of developing a second leukemia called acute myeloid leukemia (AML). The disease occurs in less than 5 percent of patients. Children also have a slight risk of later developing non-Hodgkin's lymphoma.

Radiation
This form of treatment uses high-energy rays to damage or kill cancer cells. For ALL, radiation usually comes from a machine outside the body (external beam radiation therapy) and is generally restricted to the brain, for treatment of central nervous system leukemia. Side effects include tiredness, mild skin reactions, upset stomach and loose bowels.

Bone marrow transplantation-The doctor first gives high doses of chemotherapy, possibly along with radiation, to destroy all of the patient's bone marrow. The doctor then takes healthy marrow from a donor whose tissue matches the patient's as closely as possible. The donor can be someone not related to the patient; however, the best matches usually come from a brother or sister, preferably an identical twin. The healthy marrow is infused into the patient's vein; from there it finds its way to the bones and replaces the destroyed marrow.

In an autologous bone marrow transplant, marrow is taken from the patient, treated to "cleanse" it of cancer cells, and then frozen. The patient then receives high-dose chemotherapy, with or without radiation therapy, to destroy the remaining marrow. The stored marrow is thawed and is injected to replace the marrow that was destroyed. The advantage of this procedure is that the patient receives his or her own bone marrow, so there is no risk of rejection. One drawback of this procedure is that not all cancer cells may be killed, and returning leukemia cells to the body could cause the patient to relapse.