In the United States, about 29,000 adults and 2,000 children each year are diagnosed with leukemia. This type of cancer starts in bone marrow or other blood-forming tissue, and causes large numbers of abnormal blood cells to be produced and enter the bloodstream. In time, the abnormal blood cells may crowd out normal white blood cells, red blood cells, and platelets, which makes it hard for blood to do its work. Treatment options for leukemia can include chemotherapy, other drug therapy, and biological therapy.
Leukemia is cancer that starts in blood-forming tissue, such as the bone marrow, and causes large numbers of blood cells to be produced and enter the bloodstream. Each year, it is diagnosed in about 29,000 adults and 2,000 children in the United States.
Blood cells form in the bone marrow. Bone marrow is the soft material in the center of most bones. Immature blood cells are called stem cells and blasts. Most blood cells mature in the bone marrow and then move into the blood vessels. Blood that flows through the blood vessels and the heart is called peripheral blood.
In people with leukemia, the bone marrow produces abnormal white blood cells, which are leukemia cells. At first, these cells function almost normally. In time, they may crowd out normal white blood cells, red blood cells, and platelets, which makes it hard for blood to do its work.
The different types of leukemia are grouped by how quickly the disease develops and gets worse (chronic versus acute). The types are also categorized by which blood cells are affected (lymphoid versus myeloid).
There are four common types of this disease:
Hairy cell leukemia is a rare type of the condition.
(Click Types of Leukemia for more information about this topic.)