LEUKEMIA is a disease known also as cancer of the blood and the blood-forming tissues. It is characterized by overproduction of immature atypical white blood cells, which can be detected in the blood vessels. The white blood cells, called leukocytes, are produced in the bone marrow, spleen, and lymph glands as well as in other endothelial tissues.
Leukemia occurs throughout the world. In the U.S. about 70,000 cases are under treatment each year. About 22,000 new cases are reported annually, and about 15,000 people die of leukemia each year. The disease constitutes half the cancer cases in children under the age of 15.
The exact cause of most leukemia remains unknown. Exposure to high-energy ionizing radiation can cause the disease, however, and certain chemicals such as benzene may also be responsible for its initiation. Human T-cell leukemia is known to be caused by two viruses ( see HTLV ), and certain abnormalities in chromosomes have been linked with some leukemia.
Leukemia may be classified according to the blood cell or cell series that predominates in the peripheral blood. Thus, myelocytic leukemia is characterized by proliferation of myelocytes; lymphocytic leukemia, by immature lymphocytes; and monocytic leukemia, by immature monocytes.
Two clinical forms of leukemia are recognized: acute and chronic. Acute leukemia is most common in children and in young adults, whereas the chronic form is found most often in middle-aged persons.
The clinical symptoms of acute leukemia are irregular fever; a tendency to hemorrhage from the gums and mucous membranes and under the skin; and a rapidly developing anemia. In addition, chronic myelocytic leukemia is characterized by enlargement of the spleen and chronic lymphocytic leukemia by enlargement of the lymph nodes.
Both radiation therapy and chemotherapy are used to treat leukemia. In cases of acute leukemia, such treatment leads to apparent cures in about 50 percent of the patients, and up to 90 percent of them show remissions of three or more years. Chronic myelocytic leukemia can now be treated with similar rates of success. One rare form of the disease has been found to respond somewhat to treatment with interferon. In addition, Chinese researchers have reported finding a mitochondrial marker for predicting the onset of acute leukemia; if proven, this would be important for the early treatment of the disease.
Last Updated: 05 May 2010 03:58 PM