Acute Myelogenous Leukemia
Acute myeloid leukemia (AML) is also called acute myelogenous leukemia, acute myeloblastic leukemia, acute granulocytic leukemia, or acute nonlymphocytic leukemia. In AML, the myeloid stem cells usually develop into a type of immature white blood cell called myeloblasts (or myeloid blasts). The myeloblasts, or leukemia cells, in AML are abnormal and do not become healthy white blood cells. The leukemia cells can build up in the blood and bone marrow so there is less room for healthy white blood cells, red blood cells, and platelets. When this happens, infection, anemia, or easy bleeding may occur. The leukemia cells can spread outside the blood to other parts of the body, including the central nervous system (brain and spinal cord), skin, and gums. Sometimes leukemia cells form a solid tumor called a granulocytic sarcoma or chloroma.
There are subtypes of AML based on the type of blood cell that is affected. The treatment of AML is different when it is a subtype called acute promyelocytic leukemia (APL) or when the child has Down syndrome.
Stages of Acute Myelogenous Leukemia
The extent or spread of cancer is usually described as stages. In childhood acute myeloid leukemia (AML), the subtype of AML and whether the leukemia has spread outside the blood and bone marrow are used, instead of the stage, to plan treatment. The following tests and procedures may be used to determine if the leukemia has spread:
Lumbar puncture: A procedure used to collect cerebrospinal fluid (CSF) from the spinal column. This is done by placing a needle into the spinal column. This procedure is also called an LP or spinal tap.
Biopsy of the testicles, ovaries, or skin: The removal of cells or tissues from the testicles, ovaries, or skin so they can be viewed under a microscope to check for signs of cancer. This is done only if something unusual about the testicles, ovaries, or skin is found during the physical exam.
There is no standard staging system for childhood AML, childhood chronic myelogenous leukemia (CML), juvenile myelomonocytic leukemia (JMML), transient myeloproliferative disorder (TMD), or myelodysplastic syndromes (MDS). Childhood AML is described as newly diagnosed, in remission, or recurrent.
Newly diagnosed childhood AML
Newly diagnosed childhood AML has not been treated except to relieve symptoms such as fever, bleeding, or pain, and one of the following is true:
More than 20% of the cells in the bone marrow are blasts (leukemia cells). or
Less than 20% of the cells in the bone marrow are blasts and there is a specific change in the chromosome.
Childhood AML in remission
In childhood AML in remission, the disease has been treated and the following are true:
The complete blood count is almost normal.
Less than 5% of the cells in the bone marrow are blasts (leukemia cells).
There are no signs or symptoms of leukemia in the brain, spinal cord, or other parts of the body.
Recurrent Childhood Acute Myeloid Leukemia
Recurrent childhood acute myeloid leukemia (AML) has recurred (come back) after it has been treated. The cancer may come back in the blood and bone marrow or in other parts of the body.
Treatment of Acute Myelogenous Leukemia
The treatment of childhood AML usually has two phases.
Induction therapy: This is the first phase of treatment. Its purpose is to kill the leukemia cells in the blood and bone marrow. This puts the leukemia into remission.
Consolidation /intensification therapy: This is the second phase of treatment. It begins once the leukemia is in remission. The purpose of postremission therapy is to kill any remaining leukemia cells that may not be active but could begin to regrow and cause a relapse.
Treatment called central nervous system (CNS) sanctuary therapy may be given during the induction phase of therapy. Because chemotherapy that is given by mouth or injected into a vein may not reach leukemia cells in the CNS (brain and spinal cord), the cells are able to find "sanctuary" (hide) in the CNS. Intrathecal chemotherapy and radiation therapy are able to reach and kill leukemia cells in the CNS and prevent the cancer from recurring (coming back). CNS sanctuary therapy is also called CNS prophylaxis.
Seven types of standard treatment are used for childhood AML, childhood CML, JMML, TMD, or MDS:
Stem cell transplantation
Targeted therapy with a tyrosine kinase inhibitor
Other drug therapy
New types of treatment are being tested in clinical trials:
Targeted therapy is a type of treatment that uses drugs or other substances to identify and attack specific cancer cells without harming normal cells. Monoclonal antibodies, proteasome inhibitors, and natural killer (NK) cells are three types of targeted therapies being studied in the treatment of childhood AML.
Monoclonal antibody therapy uses antibodies made in the laboratory, from a single type of immune system cell. These antibodies can identify substances on cancer cells or normal substances that may help cancer cells grow. The antibodies attach to the substances and kill the cancer cells, block their growth, or keep them from spreading. Monoclonal antibodies are given by infusion. They may be used alone or to carry drugs, toxins, or radioactive material directly to cancer cells. Monoclonal antibodies may be used in combination with chemotherapy as adjuvant therapy.
Proteasome inhibitors break down proteins in cancer cells and kill them. Bortezomib is a proteasome inhibitor used to treat childhood acute promyelocytic leukemia. Natural killer (NK) cells are white blood cells that can kill tumor cells. These may be taken from a donor and given to the patient by infusion to help kill leukemia cells.
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Adapted from the National Cancer Institute's PDQ Database: http://www.cancer.gov/cancertopics/pdq/treatment/childAML/Patient/page1. (Accessed July 2016)