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27,900 adults and 2,300 children are diagnosed each year with leukemia in the US.
Leukemia, first recognized by the German pathologist Rudolf Virchow in 1847, starts when tissues such as bone marrow behave abnormally. This is caused by mutations in the DNA of bone marrow stem cells. Bone marrow stem cells produce billions of red blood cells and white blood cells each day, respectively carrying oxygen and fighting disease around all parts of the body. Leukemia is characterized by an excessive production of abnormal white blood cells, overcrowding the bone marrow. This results in decreased production and function of normal blood cells. Leukemia can spread to the lymph nodes, spleen, liver, central nervous system and other organs.
As with all cancers, leukemia is a broad term covering a spectrum of diseases. In leukemia, the diseases are classified according to the type of abnormal cell found most in the blood. Leukemia is also clinically split in to its acute and chronic forms. The four main forms are:
The most common forms in adults are AML and CLL, whereas in children ALL is most widely observed.
Damage to the bone marrow results in a lack of blood platelets, which are important in the blood clotting process. This means people with leukemia may become bruised or bleed excessively. Similarly, the red blood cell deficiency leads to shortness of breath and fatigue (red blood cells are needed to carry oxygen efficiently around the body). Bone or joint pain may occur, possibly because of cancer spreading to these areas. Headaches and vomiting are indicative of the cancer having dispersed to the central nervous system. All symptoms may also be attributable to other diseases; for diagnosis, blood tests and a bone marrow biopsy are required.
From Wikipedia, the free encyclopedia.