Leukemia is a rare disease which affects the blood. Advances in treatment are being made all the time--in some cases it can now be cured and in most instances life can be prolonged.

Leukemia, a cancer of the blood in which certain white blood cells grow in an uncontrolled manner, can be relieved by modern treatment using chemicals, blood transfusion and radiation therapy. The uncontrolled growth of the white blood cells harm the body in many ways. Useless white cells invade the tissues and the blood. The center part of the bones called bone marrow lose their ability to produce normal blood cells of all kinds. This leads to a deficiency of red blood cells and lack of normal white blood cells, which are needed to fight infection, and defend the body against germs and viruses. Deficiency of red blood cells and lack of normal white blood cells, frequent bleeding, and repeated infection are common signs of leukemia.

Doctors classify leukemia according to the type of white blood cells affected. As stated in The World Book Encyclopedia, there are at least three kinds of white blood cells: granulocytes, lymphocytes, and monocytes. Leukemia may affect any of the three and can either be classified as acute or chronic. Chronic leukemia develops at a slower rate than acute leukemia and may continue for years. Acute leukemia on the other hand, develops very rapidly and

the patient may die within months. An individual with chronic leukemia may not be aware of their illness unless something such as a blood count is done. As the condition progresses there may be weakness, fatigue, weight loss, loss of appetite, enlarged spleen, anemia, and bone pain. Medicines such as busulfan, melphalan, and chlorambucil are used to treat chronic leukemia. In acute leukemia, blood cells cannot reproduce themselves and after a short life-span they are replaced by new cells. When untreated, acute leukemia is fatal in 1 to 2 years and often within about 6 months. Vincristine, prednisone, methotrexate, mercaptopurin, cyclophosphamide, cytarabine, and teniposide, in addition to radiation and in combination of each other, are used to treat acute leukemia. According to The Marshall Cavendish Encyclopedia of Family Health, the cause of leukemia is unknown, except in the case of acute leukemia, it is believed that it could be the result of a virus. One form of leukemia in the south-eastern U.S., Japan and the Caribbean has been shown to be caused by a particular virus called the Human T cell leukemia virus type II (HTLCII). Another factor important to the cause of leukemia is known as atomic radiation, as was witnessed by the enormous increase in the incidence of acute leukemia after the atomic bombs dropped in Japan in 1945. The incidence of chronic leukemia also increases following heavy exposure to atomic radiation. Scientists also believe that certain chemicals may contribute to the development of this disease. Genetic researchers have been able to link certain chromosome abnormalities with some forms of leukemia. Viruses are know to cause leukemia in laboratory animals, and many researchers suspect that human leukemia may also be due to a virus. Medical researchers however have only one extremely rare type of human leukemia caused by a virus.

Some signs of leukemia are when bone marrow becomes crowded by abnormal leukemia cells. It cannot function right and the patient becomes anemic through lack of red blood cells and is susceptible to infection because of lack of efficient white cells. They suffer from excessive bleeding because the blood cannot clot without platelets. Anemia may be one of the earliest symptoms and sometimes appears before any abnormal cells are in the blood. Bruising easily and repeated nose bleeds may also be signs.

Leukemia is diagnosed by examining a blood sample under a microscope. Young leukemia cells have a different look than mature blood cells. The general diagnosis is generally made by two types of blood counts, ³total² and ³differential.² Death from this disease results from the invasion of excessive amounts of white blood cells into various tissues. Recently, there has been a method found to attack leukemia without harming healthy cells. ³Researchers experimenting with mice have created a cancer Œsmart bomb¹ that attacks and kills leukemia cells without harming normal cells. The technique may be tested on humans this summer,²