The goal of initial treatment is to lower the white count and reduce the size of the spleen and liver. This is accomplished by taking oral medications, historically either hydroxyurea or busulfan (also called Myleran). More recently, STI-571 (Gleevec) or the biologic agent interferon alfa are being used. Patients with a complete response (normal physical examination, normal blood counts and bone marrow, disappearance of the Philadelphia chromosome) will have a prolongation of the chronic phase of their disease. Some may even be cured. However, most children do not achieve a complete remission. The early experience with Gleevec suggests that a higher percentage of children may achieve complete remissions. However, follow-up of these children is very short, so it is not certain how long these remissions will last.
If the spleen does not shrink after treatment with drugs or radiation, surgical removal may be required.
Although medications may slow the progress of CML, the best hope for cure is bone marrow transplantation. The highest cure rates (60 to 80 percent) occur when the child is transplanted with marrow or blood stem cells from an HLA-identical (or closely matched) family member less than one year from initial diagnosis during the chronic phase. Use of a well-matched unrelated donor gives similar results. Refer to Chapter 20 for detailed information.
The second stage or "accelerated phase" of CML is usually brief. The number of both immature white blood cells and blast cells in the bloodstream increases. The number of red blood cells drops and platelets may increase or decrease. In 2002, treatment for this phase includes high-dose cytarabine, hydroxyurea, busulfan, and/or supportive transfusion therapy (see Chapter 10). Stem cell transplants may be utilized, but the success rate (20 to 40 percent) is lower than for children who are transplanted in the chronic phase of their disease.
During the blast phase, white blood cells fail to mature and the immature cells flood the bloodstream. The blasts may have characteristics of AML (70 percent) or ALL (30 percent). Children in this phase respond poorly to standard chemotherapy for acute leukemias. Stem cell transplantation in blast crisis has a low cure rate (10 to 20 percent). The medication Gleevec has shown some promise for inducing remissions of children with blast crisis. However, these remissions are very short. A variety of experimental protocols are being tried to improve the outcomes of patients with a blast crisis. Children who achieve a complete remission should be considered for stem cell transplantation with the best available donor.
Juvenile myelomonocytic leukemia (JMML) accounts for less than one percent of childhood leukemias. It is usually diagnosed in children under two years of age and is more common in boys than in girls. Children with neurofibromatosis 1 (NF 1) are at increased risk of developing JMML.
The symptoms of JMML are similar to those of the acute leukemias: pale skin, fever, headaches, sweating, and recurrent infection. Also usually present are enlarged lymph nodes, enlarged spleen and liver, and a low platelet count. The course of JMML is unpredictable. Once diagnosed, progressive deterioration usually occurs. However, infants can survive for several years, but children older than one usually have rapidly progressive disease.
Because chemotherapy is not generally a successful treatment for JMML, bone marrow or peripheral blood stem cell transplantation is the best hope for cure. However, chemotherapy is sometimes used to get the disease under control while preparing for transplant. Cis retinoic acid may also help to achieve remission in these children.
My daughter was diagnosed with JMML in 1993 at the age of 27 months. Although it is a chronic leukemia, it is particularly fast moving, and there is no treatment besides BMT. It is also vastly different from the adult CML. My daughter had a mismatched (5/6) related (my husband's sister as donor) BMT four months after she was diagnosed. Today, she is eight years post-transplant, is in the fourth grade, and is the absolute joy of my life.
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