Treatment Options for Acute Myelogenous Leukemia (AML)
Many different chemotherapeutic plans are available for the treatment of AML. Overall, the strategy is to control bone marrow and systemic (whole-body) disease while offering specific treatment for the central nervous system (CNS), if involved. In general, most oncologists rely on combinations of drugs for the initial, induction phase of chemotherapy. Such combination chemotherapy usually offers the benefits of early remission (lessening of the disease) and a lower risk of disease resistance.
Consolidation or "maintenance" treatments may be given to prevent disease recurrence once remission has been achieved. Consolidation treatment often entails a repetition of induction chemotherapy or the intensification chemotherapy with added drugs. By contrast, maintenance treatment typically involves drug doses that are lower than those administered during the induction phase.
In addition, specific treatment plans may be used, depending on the type of leukemia that has been diagnosed. Whatever the plan, it is important for the patient to understand the treatment that is being given and the decision-making process behind the choice.
Initial treatment of AML usually begins with induction chemotherapy using a combination of drugs such as daunorubicin (DNR), cytarabine (ara-C), idarubicin, thioguanine, etoposide, or mitoxantrone.
Follow-up therapy for such patients may involve:
- supportive care, such as intravenous nutrition and treatment with oral antibiotics (e.g., ofloxacin, rifampin), especially in patients who have prolonged granulocytopenia; that is too few mature granulocytes (neutrophils), the bacteria-destroying white blood cells that contain small particles, or granules (< 100 granulocytes per cubic millimeter for 2 weeks);
- injection with colony-stimulating factors such as granulocyte colony-stimulating factor (G-CSF), which may help to shorten the period of granulocytopenia that results from induction therapy; and
- transfusions with red blood cells and platelets.
Patients with newly diagnosed disease also may be considered for stem cell transplantation (SCT), either from the bone marrow or other sources. Allogeneic bone marrow transplant (alloBMT) is reserved primarily for patients under 55 years of age who have a compatible family donor. Approximately half of newly diagnosed AML patients are in this age group, with 75% achieving a complete remission (CR) after induction and consolidation therapy. Allogeneic bone marrow transplant is available for about 15% of all patients with AML. Unfortunately, it is estimated that only 7% of all AML patients will be cured using this procedure.
People who receive stem cell transplantation (SCT, alloBMT) require protective isolation in the hospital, including filtered air, sterile food, and sterilization of the microorganisms in the gut, until their total white blood cell (WBC) count is above 500.
Treatment of central nervous system leukemia, if present, may involve injection of chemotherapeutic drugs (e.g., cytarabine or ara-C, methotrexate) into the areas around the brain and spinal cord.
Once the patient is in remission, he or she will receive consolidation or maintenance therapy, for example, consolidation therapy with high-dose ara-C (HDAC) with/without anthracycline drugs).
If, however, the AML patient has resistant disease (about 15%) or relapses (about 70%), second remissions sometimes are achieved by treating them with:
- conventional induction chemotherapy;
- high-dose ara-C (HDAC), with/without other drugs; and
- etoposide or other single chemotherapeutic agents.
Elderly AML patients have special treatment concerns. They may be less able to tolerate the septicemia (blood poisoning) associated with granulocytopenia, and they often have higher rates of myelodysplastic ('preleukemia') syndrome (MDS). Individuals who are over age 75 or who have significant medical conditions can be treated effectively with low-dose ara-C. High-dose post-induction chemotherapy is unlikely to be tolerated by elderly patients.
Until recently, the treatment plans and responses of children with AML did not differ much from those of adults. Yet new, more intensive induction and consolidation treatments have resulted in higher remission rates and prolonged survivals. Many induction trials have produced good results using combinations of cytarabine (ara-C) plus an anthracycline (e.g., daunorubicin, doxorubicin). In children under 3 years of age, the anthracycline used for induction should be chosen with care, since doxorubicin produces more toxicity and related deaths than daunorubicin.
Consolidation therapy is complex, but it should include at least two courses of high-dose ara-C (HDAC). Children who have hyperleukocytosis (too many white blood cells), especially monocytic M5 leukemia, have a poor prognosis.