Leukemia is a malignant disease (cancer) of the bone marrow and blood. It is characterized by the uncontrolled accumulation of blood cells. Leukemia is categorized into four types: myelogenous or lymphocytic, each of which can be acute or chronic. The terms myelogenous or lymphocytic denote the cell type involved. Thus, the four major types of leukemia are:

• Acute Lymphocytic Leukemia
• Chronic Lymphocytic Leukemia
• Acute Myelogenous Leukemia
• Chronic Myelogenous Leukemia

Acute leukemia is a rapidly progressing disease that results in the accumulation of immature, functionless cells in the marrow and blood. The marrow often stops producing enough normal red cells, white cells and platelets. Anemia, a deficiency of red cells, develops in virtually all persons with leukemia.

Chronic leukemia progresses more slowly and allows greater numbers of more mature, functional cells to be made.