Leukemia---cancer of the blood or bone marrow---is the result of an atypical propagation of blood cells (usually white). Usually categorized by how quickly it progresses, leukemia also can be classified by the type of white blood cell that is multiplying. Causes of leukemia are not fully understood, although researchers believe the disease may be the result of genetics or exposure to ionizing radiation or certain chemicals or viruses.
Acute Lymphocytic Leukemia
Acute lymphocytic leukemia is a type of leukemia caused by immature cells, which rapidly accumulate and reproduce, leaving little room for healthy cell production. Because this type of leukemia progresses so quickly, it must be treated immediately or fatality can occur within a short amount of time. Acute lymphocytic leukemia is the most common type of leukemia in children, but it also can affect the elderly.
Chronic Lymphocytic Leukemia
Chronic lymphocytic leukemia (CLL) occurs when the DNA of the lymphocyte cell mutates. As time passes, CLL cells multiply and replace normal cells in the marrow and lymph nodes. When this occurs, these cells crowd blood-forming cells and inhibit the body's ability to fight infection.
Acute Myelogenous Leukemia
Acute myelogenous leukemia---also called acute nonlymphocytic leukemia---occurs when white blood cells in the bone marrow develop granulocytes, small granules, that prevent the body from fighting disease and inhibit its ability to stop bleeding.
Chronic Myelogenous Leukemia
Chronic myelogenous leukemia is a type of bone marrow cancer in which cells multiply outside of the bone marrow tissue proper. The change begins in a single stem cell, most commonly in adults. Depending on the phase, the body may still be able to fight infection; however, those with more advanced phases of the disease may experience symptoms such as an enlarged spleen or frequent infections.
