Chemotherapy is the primary treatment for acute myeloid leukemia (AML) in children. Multiple chemotherapy treatments are required for a chance at long-term cure. The length of chemotherapy treatment is usually >6 months. Some patients may receive a bone marrow transplant following initial chemotherapy.
The drugs selected for treatment are based on the specific cancer diagnosis. Chemotherapy for AML may be given by mouth or injected into a vein, muscle or the central nervous system. Chemotherapy for AML is usually divided into phases of treatment.
The goal of this first phase of treatment is to kill the leukemia cells and allow normal blood cells to return. Chemotherapy works by targeting fast growing cells. It destroys fast-growing cancer cells, but it also affects “good” white blood cells in the body. After chemotherapy, it takes several weeks for healthy bone marrow to regrow. Infection is a major risk during this period, and patients remain in the hospital until there is evidence of a regrowth of healthy white blood cells. This phase of treatment usually lasts about 4 weeks, but may be longer depending upon the length of recovery of normal blood cells.
A bone marrow aspirate is performed at the end of this phase. The bone marrow is examined under a microscope. Often after the first round of chemotherapy, doctors will see no evidence of leukemia cells in the bone marrow. At that point, the disease is considered in remission. However, it is crucial to continue treatment, since there may be some cancer cells left over in the bone marrow or blood that could continue to replicate and allow the cancer to spread. However, remission is a very important first step on the road towards being cured.
The second part of treatment kills any leukemia cells remaining in the body. This phase usually lasts about 4-6 weeks. Again, infection is a major risk and patients may need to be hospitalized until there are enough healthy white blood cells to fight infection.
For some types of AML, additional chemotherapy will be necessary to kill remaining leukemia cells. This phase usually lasts about 8-12 weeks. In most children, the signs and symptoms of the disease are absent after induction, and most children will be in remission after induction. Approximately 50-60% of children will be cured of AML with current modern therapy.
For many types of AML, a bone marrow transplants (BMT) is a recommended part of treatment. If there is a family member (brother, sister, parent) who is a tissue type match, a bone marrow transplant may be recommended. The chances of staying in remission after a BMT are higher than with chemotherapy alone. Siblings of a patient (and sometimes parents) can have their blood tested to see if they are a tissue type match. Patients can also get BMT’s from unrelated donors. These transplants tend to be higher risk, so this procedure is considered in first remission only for patients at high risk for relapse.
With the following exceptions, patients all receive the same treatment:
- Down Syndrome: children with Down syndrome generally require less intensive chemotherapy to achieve a cure.
- Acute Promyelocytic Leukemia: these children receive different chemotherapy with the special medication, all-trans retinoic acid. These patients respond well to this unique therapy and generally do not receive a bone marrow transplant.
- Specific AML Risk Groups including:
- High Risk types of AML that do not respond well to standard chemotherapy. These patients often receive a blood or marrow transplant in first remission.
- Low Risk types of AML that respond well to chemotherapy. Patients may not be recommended for bone marrow transplant in first remission, even if a family member is a tissue type match.
- Central nervous system disease at diagnosis (blasts in the cerebrospinal fluid). Some children may have blast cells in the fluid collected at the first spinal tap. They receive extra chemotherapy given with spinal taps to kill these cells.
If leukemia relapses, it usually happens within the first two years following diagnosis. Additional chemotherapy may be given to get the child back into remission. There may be new therapies in research studies that may be beneficial to AML patients; your doctor may discuss these with you if they are available. Upon achieving a new remission, a bone marrow transplant will be considered to maintain remission. If a related donor is not available, then an unrelated donor may be considered.