Leukemia is cancer of the white blood cells and the cells from which they develop. The word cancer refers to diseases in which certain cells in the body become abnormal and grow unchecked. In this case, the abnormal cells are white blood cells and their precursors. Leukemia cells do not function normally and cannot do what normal white blood cells do, such as fight infections.
In addition to the abnormal cells in the blood, other, normal elements such as platelets and red cells may be decreased, leading to anemia and clotting problems.
White Blood Cells
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The most common types of leukemia are:
Acute Lymphocytic Leukemia (ALL)
—The cancer begins in immature lymphocytic blood cells and progresses very quickly. This is the most common type of leukemia in young children. It also occurs in adults, especially those over age 65. This cancer is sometimes called acute lymphoblastic leukemia or acute lymphoid anemia.
Acute Myelogenous Leukemia (AML)
—The cancer begins in immature granulocytic blood cells and progresses very quickly. This type occurs in both adults and children. Other names include acute myelocytic leukemia, acute myeloid leukemia, acute granulocytic leukemia, or acute nonlymphocytic leukemia.
Chronic Lymphocytic Leukemia (CLL)
—This cancer, also known as chronic lymphoid leukemia, begins in more mature lymphocytic blood cells and progresses gradually, often taking years to develop to the stage that the patient has symptoms other than a change in the number of white cells in his blood count. This type most often occurs in adults over age 55. It sometimes occurs in younger adults, but rarely occurs in children.
Chronic Myelogenous Leukemia (CML)
—The cancer begins in more mature granulocytic blood cells and progresses gradually, sometimes taking years to develop to the stage that the patient develops symptoms. This occurs mainly in adults, but may occur in a very small number of children. Sometimes called chronic myeloid leukemia or chronic granulocytic leukemia.
—This is a cancer of the cells that produce red cells and is extremely uncommon. Erythroleukemia may also be called di Guglielmo syndrome, after the physician who first described it.
The cause of leukemia is unknown, but research shows that certain risk factors are associated with the disease, and the risk factors will vary with the type of leukemia.
According to The Leukemia & Lymphoma Society, approximately 48,490 Americans will learn they have leukemia this year. About half will have chronic types and half will have acute forms.