According to the American Cancer Society, some 43,000 people in the United States are diagnosed with leukemia each year. This includes about:
- 15,000 cases of chronic lymphocytic leukemia (CLL), most in older adults
- 13,500 cases of acute myeloid leukemia (AML), most in adults
- 6,000 cases of acute lymphocytic leukemia (ALL), about one in three in adults
- 5,000 cases of chronic myeloid leukemia (CML), most in older adults
Leukemia is cancer of blood-forming tissue such as the bone marrow, the sponge-like material inside some bones. In healthy bone marrow, blood cells form and mature, then move into the bloodstream. Types of leukemia are grouped by the type of cell affected and by the rate of cell growth. Leukemia is either acute or chronic.
In leukemia, the normal production of blood cells changes. The bone marrow starts making too many abnormal, immature cells, called blasts or lymphoblasts, which crowd out other blood cells in the blood marrow, blood stream and lymph system. They can travel to other places in the body, including lymph glands and the spleen.