Leukemia is a type of blood cancer that begins in the bone marrow. Bone marrow is the soft tissue in the center of the bones, where blood cells are produced.
The term leukemia means white blood. White blood cells (leukocytes) are used by the body to fight infections and other foreign substances. Leukocytes are made in the bone marrow.
Leukemia leads to an uncontrolled increase in the number of white blood cells.
The cancerous cells prevent healthy red cells, platelets, and mature white cells (leukocytes) from being made. Life-threatening symptoms can then develop as normal blood cells decline.
The cancer cells can spread to the bloodstream and lymph nodes. They can also travel to the brain and spinal cord (the central nervous system) and other parts of the body.
Leukemias are divided into two major types:
Acute (which progresses quickly)
Chronic (which progresses more slowly)
The main types of leukemia are:
Appelbaum FR. The acute leukemias. In: Goldman L, Schafer AI, eds.
Goldman's Cecil Medicine. 24th ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 189.
Kantarjian H, O'Brien S. The chronic leukemias. In: Goldman L, Schafer AI, eds.
Goldman's Cecil Medicine. 24th ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 190.
Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
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