Childhood Acute Myeloid Leukemia and Other Myeloid Malignancies

Leukemia and other diseases of the blood and bone marrow may affect red blood cells, white blood cells, and platelets.

Normally, the bone marrow makes blood stem cells (immature cells) that develop into mature blood cells over time. A blood stem cell may become a myeloid stem cell or a lymphoid stem cell. The lymphoid stem cell develops into a white blood cell. The myeloid stem cell develops into one of three types of mature blood cells:

• Red blood cells that carry oxygen and other materials to all tissues of the body.
• White blood cells that fight infection and disease.
• Platelets that help prevent bleeding by causing blood clots to form.

Childhood acute myeloid leukemia (AML) is a type of cancer in which the bone marrow makes a large number of abnormal blood cells.

Cancers that are acute usually get worse quickly if they are not treated. Cancers that are chronic usually get worse slowly. 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.

Other myeloid diseases can affect the blood and bone marrow.

In chronic myelogenous leukemia (CML), too many bone marrow stem cells develop into a type of white blood cell called granulocytes. Some of these bone marrow stem cells never become mature white blood cells. These are called blasts. Over time, the granulocytes and blasts crowd out the red blood cells and platelets in the bone marrow. CML is rare in children.

Juvenile myelomonocytic leukemia (JMML) is a rare childhood cancer that occurs more often in children around the age of 2 years. In JMML, too many bone marrow stem cells develop into 2 types of white blood cells called myelocytes and monocytes. Some of these bone marrow stem cells never become mature white blood cells. These immature cells, called blasts, are unable to do their usual work. Over time, the myelocytes, monocytes, and blasts crowd out the red blood cells and platelets in the bone marrow. When this happens, infection, anemia, or easy bleeding may occur.

Transient myeloproliferative disorder (TMD) is a disorder of the bone marrow that can develop in newborns who have Down syndrome. This disorder usually goes away on its own within the first 3 weeks of life. Infants who have Down syndrome and TMD have an increased chance of developing AML before the age of 3 years.

In myelodysplastic syndromes (MDS), the bone marrow makes too few red blood cells, white blood cells, and platelets. These blood cells may not mature and enter the blood. The treatment for MDS depends on how much lower than normal the number of red blood cells, white blood cells, or platelets is. MDS may progress to AML.

Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. People who think they may be at risk should discuss this with their doctor. Possible risk factors for childhood AML, childhood CML, JMML, TMD, and MDS include the following:

• Having a brother or sister, especially a twin, with leukemia.
• Being Hispanic.
• Being exposed to cigarette smoke or alcohol before birth.
• Having a history of MDS (also called preleukemia) or aplastic anemia.
• Past treatment with chemotherapy or radiation therapy.
• Being exposed to ionizing radiation or chemicals such as benzene.
• Having certain genetic disorders, such as Down syndrome, Fanconi anemia, neurofibromatosis type 1, or Noonan syndrome.

These and other symptoms may be caused by childhood AML, childhood CML, JMML, or MDS. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur:

• Fever with or without an infection.
• Night sweats.
• Shortness of breath.
• Weakness or feeling tired.
• Easy bruising or bleeding.
• Petechiae (flat, pinpoint spots under the skin caused by bleeding).
• Pain in the bones or joints.
• Pain or feeling of fullness below the ribs.
• Painless lumps in the neck, underarm, stomach, groin, or other parts of the body. When seen in childhood AML, these lumps, called leukemia cutis, may be blue or purple.
• Painless lumps that are sometimes around the eyes. These lumps, called chloromas, are sometimes seen in childhood AML and may be blue-green.
• An eczema -like skin rash.

The symptoms of TMD may include the following:

• Swelling all over the body.
• Shortness of breath.
• Trouble breathing.
• Weakness or feeling tired.
• Pain below the ribs.

The following tests and procedures may be used:

• Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
• Complete blood count (CBC): A procedure in which a sample of blood is drawn and checked for the following:
  --The number of red blood cells, white blood cells, and platelets.
  --The amount of hemoglobin (the protein that carries oxygen) in the red blood cells.
  --The portion of the sample made up of red blood cells.

• Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease in the organ or tissue that makes it.
• Chest x-ray: An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
• Peripheral blood smear: A procedure in which a sample of blood is checked for blast cells, number and kinds of white blood cells, number of platelets, and changes in the shape of the blood cells.
• Biopsy: The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer. Biopsies that may be done for childhood AML include the following:
  --Bone marrow aspiration and biopsy: The removal of bone marrow, blood, and a small piece of bone by inserting a hollow needle into the hipbone or breastbone.
  --Tumor biopsy: A biopsy of a chloroma may be done.
  --Lymph node biopsy: The removal of all or part of a lymph node.

• Cytogenetic analysis: A laboratory test in which cells in a sample of blood or bone marrow are viewed under a microscope to look for certain changes in the chromosomes.
• Immunophenotyping: A process used to identify cells, based on the types of antigens or markers on the surface of the cell that may include special staining of the blood and bone marrow cells. This process is used to diagnose the subtype of AML by comparing the cancer cells to normal cells of the immune system.
• Lumbar puncture: A procedure used to collect cerebrospinal fluid 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.

The prognosis (chance of recovery) and treatment options for childhood AML depend on the following:

• The age of the child at diagnosis.
• Number of white blood cells in the blood at diagnosis.
• Whether the AML was caused by previous anticancer treatment.
• The subtype of AML.
• Whether there are certain chromosomal changes in the leukemia cells.
• Whether the child has Down syndrome. Most children with AML and Down syndrome can be cured of their leukemia.
• How well the leukemia responds to initial treatment.
• Whether the AML is newly diagnosed or has recurred (come back) after being treated.
• The length of time since treatment ended, for AML that has recurred.

The prognosis and treatment options for childhood CML depend on how long it has been since the patient was diagnosed and how many blast cells are in the blood.

The prognosis (chance of recovery) and treatment options for JMML depend on the following:

• The age of the child at diagnosis.
• How many red blood cells, white blood cells, or platelets are in the blood.
• Whether the JMML is untreated or has recurred after treatment.

The prognosis (chance of recovery) and treatment options for MDS depend on the following:

• Whether the MDS was caused by previous cancer treatment.
• How low the numbers of red blood cells, white blood cells, or platelets are.
• Whether the MDS is untreated or has recurred after treatment.

Stages of Childhood Acute Myeloid Leukemia and Other Myeloid Malignancies

Once childhood acute myeloid leukemia (AML) has been diagnosed, tests are done to find out if the cancer has spread to other parts of the body.

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 are three ways that cancer spreads in the body.

When cancer cells spread outside the blood, a solid tumor may form. This process is called metastasis. The three ways that cancer cells spread in the body are:

• Through the blood. Cancer cells travel through the blood, invade solid tissues in the body, such as the brain or heart, and form a solid tumor.
• Through the lymph system. Cancer cells invade the lymph system, travel through the lymph vessels, and form a solid tumor in other parts of the body.
• Through solid tissue. Cancer cells that have formed a solid tumor spread to tissues in the surrounding area.

The new (metastatic) tumor is the same type of cancer as the primary cancer. For example, if leukemia cells spread to the brain, the cancer cells in the brain are actually leukemia cells. The disease is metastatic leukemia, not brain cancer.

Childhood AML is described as newly diagnosed, in remission, or recurrent.

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.

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 option overview

Different types of treatment are available for children with AML, CML, JMML, TMD, or MDS. Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment.

Because cancer in children is rare, taking part in a clinical trial should be considered. Some clinical trials are open only to patients who have not started treatment.

Treatment will be overseen by a pediatric oncologist, a doctor who specializes in treating children with cancer. The pediatric oncologist works with other health care providers who are experts in treating children with leukemia and who specialize in certain areas of medicine. These may include the following specialists:

• Hematologist
• Medical oncologist
• Pediatric surgeon
• Radiation oncologist
• Neurologist
• Neuropathologist
• Neuroradiologist
• Pediatric nurse specialist
• Social worker
• Rehabilitation specialist
• Psychologist

Regular follow-up exams are very important. Some cancer treatments cause side effects that continue or appear months or years after cancer treatment has ended. These are called late effects. Late effects of cancer treatment may include:

• Physical problems
• Changes in mood, feelings, thinking, learning, or memory
• Second cancers (new types of cancer)

Some late effects may be treated or controlled. It is important that parents of children who are treated for AML or other blood diseases talk with their doctors about the effects cancer treatment can have on their child.

The treatment of childhood AML is done in 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.

Six types of standard treatment are used for childhood AML, childhood CML, JMML, TMD, or MDS.

Chemotherapy

Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy). When chemotherapy is placed directly into the spinal column (intrathecal chemotherapy), an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy). Combination chemotherapy is treatment using more than one anticancer drug.

The way the chemotherapy is given depends on the type of cancer being treated.

In AML, the leukemia cells may spread to the brain and/or spinal cord. Anticancer drugs given by mouth or vein to treat AML cannot cross the blood-brain barrier and enter the fluid that surrounds the brain and spinal cord. Instead, an anticancer drug is injected into the fluid-filled space to kill leukemia cells that may have spread there. This is called intrathecal chemotherapy.

Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. There are two types of radiation therapy. External radiation therapy uses a machine outside the body to send radiation toward the cancer. Internal radiation therapy uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near the cancer. External radiation therapy may be used to treat childhood AML that has spread, or may spread, to the brain and spinal cord. When used this way, it is called central nervous system (CNS) sanctuary therapy or CNS prophylaxis.

Stem cell transplant is a way of giving chemotherapy and replacing blood-forming cells that are abnormal or destroyed by the cancer treatment. Stem cells (immature blood cells) are removed from the blood or bone marrow of the patient or a donor and are frozen and stored. After the chemotherapy is completed, the stored stem cells are thawed and given back to the patient through an infusion. These reinfused stem cells grow into (and restore) the body's blood cells.

Arsenic trioxide and all-trans retinoic acid (ATRA) are anticancer drugs that kill leukemia cells, stop the leukemia cells from dividing, or help the leukemia cells mature into white blood cells. These drugs are used in the treatment of a subtype of AML called acute promyelocytic leukemia (APL).

Imatinib (Gleevec) is a type of anticancer drug called a tyrosine kinase inhibitor. It blocks the enzyme, tyrosine kinase, that causes stem cells to develop into more white blood cells (granulocytes or blasts) than the body needs.

Watchful waiting is closely monitoring a patient’s condition without giving any treatment until symptoms appear or change. It is sometimes used to treat MDS or TMD.

Supportive care is given to lessen the problems caused by the disease or its treatment. Supportive care may include the following:

• Transfusion therapy: A way of giving red blood cells, white blood cells, or platelets to replace blood cells destroyed by disease or cancer treatment. The blood may be donated from another person or it may have been taken from the person earlier and stored until needed.
• Drug therapy, such as antibiotics.
• Leukapheresis: A procedure in which a special machine is used to remove white blood cells from the blood. Blood is taken from the patient and put through a blood cell separator where the white blood cells are removed. The rest of the blood is then returned to the patient's bloodstream.

New types of treatment are being tested in clinical trials

Biologic therapy is a treatment that uses the patient’s immune system to fight cancer. Substances made by the body or made in a laboratory are used to boost, direct, or restore the body’s natural defenses against cancer. This type of cancer treatment is also called biotherapy or immunotherapy.

Monoclonal antibody therapy is a certain type of biologic therapy. Monoclonal antibody therapy is a cancer treatment that 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.

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.

For some patients, taking part in a clinical trial may be the best treatment choice. Clinical trials are part of the cancer research process. Clinical trials are done to find out if new cancer treatments are safe and effective or better than the standard treatment.

Many of today's standard treatments for cancer are based on earlier clinical trials. Patients who take part in a clinical trial may receive the standard treatment or be among the first to receive a new treatment.

Patients who take part in clinical trials also help improve the way cancer will be treated in the future. Even when clinical trials do not lead to effective new treatments, they often answer important questions and help move research forward.

Some clinical trials only include patients who have not yet received treatment. Other trials test treatments for patients whose cancer has not gotten better. There are also clinical trials that test new ways to stop cancer from recurring (coming back) or reduce the side effects of cancer treatment.

Some of the tests that were done to diagnose the cancer or to find out the stage of the cancer may be repeated. Some tests will be repeated in order to see how well the treatment is working. Decisions about whether to continue, change, or stop treatment may be based on the results of these tests. This is sometimes called re-staging.

Some of the tests will continue to be done from time to time after treatment has ended. The results of these tests can show if your condition has changed or if the cancer has recurred (come back). These tests are sometimes called follow-up tests or check-ups.

Treatment Options for Childhood Acute Myeloid Leukemia, Myelodysplastic Syndromes, and Juvenile Myelomonocytic Leukemia

Newly Diagnosed Childhood Acute Myeloid Leukemia

Treatment of newly diagnosed childhood acute myeloid leukemia may include the following:

• Combination chemotherapy plus central nervous system sanctuary therapy (intrathecal chemotherapy with or without radiation therapy to the brain).
• A clinical trial comparing different chemotherapy regimens (doses and schedules of treatment).

Treatment of newly diagnosed childhood acute leukemia with a granulocytic sarcoma (chloroma) may include chemotherapy with or without radiation therapy.

Treatment of childhood acute myeloid leukemia (AML) during the remission phase (consolidation /intensification therapy) depends on the subtype of AML and may include the following:

• Combination chemotherapy.
• Stem cell transplant.
• A clinical trial of combination chemotherapy with or without a monoclonal antibody and/or stem cell transplant.
• A clinical trial of a natural killer cell transplant after chemotherapy.

Treatment of recurrent childhood acute myeloid leukemia may include the following:

• Combination chemotherapy
• Combination chemotherapy and stem cell transplant.
• A clinical trial of a new anticancer drug.
• A clinical trial of biologic therapy.
• A clinical trial of stem cell transplant using different sources of stem cells.

Treatment of recurrent acute promyelocytic leukemia may include all-trans retinoic acid or arsenic trioxide therapy.

Treatment of acute promyelocytic leukemia may include the following:

• All-trans retinoic acid (ATRA) plus chemotherapy.
• Arsenic trioxide therapy.
• Combination chemotherapy.
• A clinical trial of chemotherapy and ATRA with or without arsenic trioxide.
• A clinical trial of a monoclonal antibody with ATRA.
• A clinical trial of ATRA plus arsenic trioxide.

Supportive care treatments are used to manage problems caused by the disease, such as infection, bleeding, and anemia.

Treatment of acute myeloid leukemia in children who have Down syndrome may include the following:

• Combination chemotherapy.
• A clinical trial of lower- dose chemotherapy.

Treatment for childhood chronic myelogenous leukemia may include the following:

• Stem cell transplant.
• Drug therapy with Gleevec.
• A clinical trial of stem cell transplant using lower doses of chemotherapy.

Treatment of juvenile myelomonocytic leukemia is usually stem cell transplant.

Transient myeloproliferative disorder (TMD) usually goes away on its own. For TMD that does not go away on its own, treatment may include the following:

• Transfusion therapy
• Leukapheresis
• Chemotherapy

Treatment of myelodysplastic syndromes (MDS) may include the following:

• Stem cell transplant.
• Combination chemotherapy.
• A clinical trial of a new anticancer drug.

Supportive care treatments are used to manage problems caused by the disease, such as infection, bleeding, and anemia.

If the MDS progresses to acute myeloid leukemia (AML), treatment will be the same as treatment for the newly diagnosed patient with AML.

Source: National Institutes of Health; National Cancer Institute

This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. For additional written health information, please contact the Health Information Center at the Cleveland Clinic (216) 444-3771 or toll-free (800) 223-2273 extension 43771 or visit www.clevelandclinic.org/health/.

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