Acute myelogenous leukemia (also called acute myeloid leukemia, acute non-lymphocytic leukemia, or AML) is cancer of the granulocytes (a type of white blood cell). Approximately 500 cases of AML are diagnosed in the United States each year. The incidence is highest in the first 2 years of life. Incidence rates gradually decrease until 9 years of age and then slowly increase during adolescence.

Description

AML is a cancer that begins in the blood-forming tissues of the bone marrow—the spongy center of the bones that produces blood cells. In AML, the bone marrow creates too many immature granulocytes (a type of white cell) that cannot perform their normal function of fighting infection. As the bone marrow floods the bloodstream with immature white cells, production of healthy white cells, red cells (which carry oxygen), and platelets (which form clots to stop bleeding) slows and stops. The blood carries the leukemic cells to organs such as the lungs, liver, spleen, and kidneys. The cancer can also cross the blood-brain barrier and invade the central nervous system (CNS)—made up of the brain and spinal cord.

AML is grouped into subtypes by the presence of genetic abnormalities in the leukemia cells. AML that doesn’t fall into these categories is grouped into eight different subtypes of AML—M0 to M7—based on cell shape and chemical properties.

Treatment

Treatment for AML is intensive. Treatment is ordinarily divided into two or three phases: induction (to attain remission), stem cell transplantation or post-remission consolidation, and/or post-remission intensification. Maintenance therapy is no longer used in most current protocols. Intrathecal (through a needle into the spine) chemotherapy is used to prevent leukemia in the CNS.

Chemotherapy

Chemotherapy for AML includes combinations of drugs that may include cytarabine (ARA-C), fludarabine (Fludara ^® ), cladribine (Leustatin ^® ), azacytidine, clofarabine (Clolar ^® ), daunorubicin (Cerubidine ^® ), etoposide (VP-16 or Vepesid ^® ), idarubicin (Idamycin ^® ), mitoxantrone (Novantrone ^® ), and amsacrine (Amsidine ^® ). More recently, biological response modifiers such as sorafenib (Nexavar ^® ) have been used to treat AML. Intrathecal chemotherapy includes cytarabine, methotrexate, and hydrocortisone to treat or prevent leukemia in the CNS.

All types of AML except M3 (called promylocytic leukemia or APML) are treated similarly. The inclusion of all-trans-retinoic acid into M3 protocols has doubled the remission rates for this subtype of AML.

Stem Cell Transplantation

After obtaining a remission, treatment with additional chemotherapy or stem cell transplantation is necessary. Information about the late effects of stem cell transplants is available at the end of this chapter under “Stem cell transplantation.”

Late effects

Some children who were treated with chemotherapy alone have few or no long-term effects. Children who had stem cell transplants or children who relapsed and require more intensive treatment sometimes pay a higher price. The following information briefly outlines some common and uncommon late effects from treatment. Remember that you may develop none, a few, or several of these problems in the months or years after treatment ends.

Heart problems. Heart problems can occur months or years after treatment with anthracyclines (i.e., doxorubicin, idarubicin, or daunorubicin), high-dose cyclophosphamide, and chest radiation. Symptoms include shortness of breath, fatigue, wheezing, anxiety, poor exercise tolerance, rapid heartbeat, and irregular heartbeat. The number of AML survivors who develop this late effect is small, but regular checkups are crucial. Survivors often have no symptoms, but problems may be found on cardiac tests such as echocardiograms, electrocardiograms (EKGs), and Holter monitors. For more information, see Chapter 12 .

Fatigue. After treatment for AML, most children resume normal activities at age-appropriate levels, but some children have fatigue. These children, usually those who have received cranial radiation and/or had stem cell transplants, may have long-term troubles with strength, coordination, and weakness. For more information, see Chapter 7 .

Hepatitis C. Infection with the hepatitis C virus can develop in survivors who had blood transfusions prior to July 1992. For more information, see Chapter 15 .

Dental problems. Dental abnormalities such as failure of the teeth to develop, arrested root development, unusually small teeth, and enamel abnormalities occasionally occur after chemotherapy or radiation. For more information, see Chapter 11 .

Less common problems. Less common late effects include bladder problems (i.e., hemorrhagic cystitis and bladder fibrosis) from cyclophosphamide and osteonecrosis (death of blood vessels that nourish bones) from high-dose steroids. Children who receive cranial radiation have a small risk of developing a secondary cancer. Those treated with VP-16 have a slight chance of a second leukemia, which usually develops within 3 to 5 years after treatment. For more information, see Chapter 19 .

Descriptions of stem cell transplants and their late effects are at the end of this chapter.