What Is Leukemia ?

Leukemia is a type of cancer. Cancer is a group of more than 100 diseases that have two important things in common. One is that certain cells in the body become abnormal. Another is that the body keeps producing large numbers of these abnormal cells. Leukemia is cancer of the blood cells. To understand leukemia, it is helpful to know about normal blood cells and what happens to them when leukemia develops.

Acute leukemia versus Chronic leukemia

The first factor to consider in classifying a patient's leukemia is whether most of the abnormal cells are mature (resemble normal circulating white blood cells) or immature.
In acute leukemia, the bone marrow cells are unable to properly mature. Immature leukemic cells continue to reproduce and accumulate. Without treatment, most patients with acute leukemia would live less than a few months. Some subtypes of acute leukemia respond well to treatment and many patients are cured, while other types of acute leukemia have a less favorable outlook.
In chronic leukemia the cells can mature. Although the chronic leukemia cells look mature, they are not completely normal and do not fight infection as well as normal white blood cells do. Overproduction of cells is not the main problem in chronic leukemia. The problem is that chronic leukemia cells live much longer than normal white blood cells, resulting in accumulation of too many mature granulocytes or lymphocytes.

Myelogenous leukemia versus lymphocytic leukemia

The second factor to consider in classifying leukemia is the type of bone marrow cells that are affected. If granulocytes or monocytes are involved, the leukemia is classified as myelogenous leukemia.
If the cancer develops from bone marrow lymphocytes, it is called lymphocytic leukemia. Malignant lymphomas are also cancers of lymphocytes. But, unlike lymphocytic leukemias which develop in the bone marrow, lymphomas develop from lymphocytes in lymph nodes or other organs.
By considering whether a leukemia is acute versus chronic and myelogenous versus lymphocytic, leukemias can be divided into one of four main types.

Childhood Leukemia

The exact cause of childhood leukemia is a mystery, but certain factors are known to increase the risk of developing the disease. Children with chromosomal abnormalities such as Down's syndrome or Franconi's anemia have a higher risk of developing leukemia than the general population. Exposure to large amounts of ionizing radiation (such as that released by the Chernobyl accident in the Ukraine) and toxic chemicals (including chronic exposure to benzene) may increase susceptibility to leukemia. It is thought that a complex interaction among genetic, environmental, immunologic, and possibly viral factors predispose individuals to leukemia. The most important point for parents to remember is that at present there is no way to predict or prevent leukemia.

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