Acute Myeloid Leukemia

Acute leukemia is a malignant proliferation of white blood cell precursors (blasts) in bone marrow or lymph tissue and their accumulation in peripheral blood, bone marrow, and body tissues.The most common forms are acute lymphoblastic (lymphocytic) leukemia (ALL), characterized by the abnormal growth of lymphocyte precursors (lymphoblasts); acute myeloblastic (myelogenous) leukemia (AML), in which myeloid precursors (myeloblasts) rapidly accumulate; and acute monoblastic (monocytic) leukemia, or Schilling's type, characterized by a marked increase in monocyte precursors (monoblasts). Other variants include acute myelomonocytic leukemia and acute erythroleukemia.

Untreated, acute leukemia is invariably fatal, usually because of complications that result from leukemic cell infiltration of bone marrow or vital organs. With treatment, the prognosis varies.

In ALL, treatment induces remissions in 90% of children (average survival time: 5 years) and in 65% of adults (average survival time:1 to 2 years). Children ages 2 to 8 have the best survival rate with intensive therapy.

In AML, the average survival time is only 1 year after diagnosis, even with aggressive treatment. In acute monoblastic leukemia, treatment induces remissions lasting 2 to 10 months in 50% of children; adults survive only about 1 year after diagnosis, even with treatment.

Causes

Research on predisposing factors isn't conclusive but points to some combination of viruses (viral remnants have been found in leukemic cells), genetic and immunologic factors, and exposure to radiation and certain chemicals.

Pathogenesis isn't clearly understood, but immature, nonfunctioning white blood cells (WBCs) appear to accumulate first in the tissue where they originate (lymphocytes in lymph tissue, granulocytes in bone marrow). These immature WBCs then spill into the bloodstream and from there infiltrate other tissues, eventually causing organ malfunction because of encroachment or hemorrhage.

Incidence

Acute leukemia is more common in males than in females, in whites (especially people of Jewish descent), in children between ages 2 and 5 (80% of all leukemias in this age-group are ALL), and in people who live in urban and industrialized areas. Acute leukemia ranks 20th in causes of cancer-related deaths among people of all age-groups. Among children, however, it's the most common form of cancer. In the United States, an estimated 11,000 people develop acute leukemia annually.

Signs and symptoms

Symptoms of leukemia are associated with the impaired production and function of these components such as:

• Paleness
• Tiredness
• Bleeding or bruising
• Recurrent fevers

The duration of symptoms prior to diagnosis can last from days to months because of the non-specific nature of the symptoms that can mimic other more common childhood illness.

Diagnosis

Typical clinical findings and bone marrow aspirate showing a proliferation of immature WBCs confirm acute leukemia. An aspirate that's dry or free of leukemic cells in a patient with typical clinical findings requires a bone marrow biopsy, usually of the posterior superior iliac spine.

Blood counts show thrombocytopenia and neutropenia. A differential leukocyte count determines cell type. Lumbar puncture detects meningeal involvement.

Treatment

Leukemia is treated with special medications known as chemotherapy.  Radiation may also be necessary in the treatment.  Treatment typically lasts 2-3 years and is tolerated quite well by most children and is primarily provided on an outpatient basis.

Treatment by a childhood cancer specialist is preferable. Most childhood cancer centers belong to the Children's Oncology Group.  They are responsible for the development of clinical trials (treatment plans) specifically for children, adolescents and young adults.

A bone marrow transplant may be possible. Treatment also may include antibiotic, antifungal, and antiviral drugs and granulocyte injections to control infection. Transfusions may be given of platelets (to prevent bleeding) and red blood cells (to prevent anemia).

Prevention

Get protection from any work-related exposure to agents associated with the development of acute leukemia . Minimize radiation exposure