Leukemia

Leukemia is a type of cancer that starts in blood-forming tissue, such as the bone marrow, and causes large numbers of abnormal white blood cells to be produced and enter the bloodstream. Unlike normal blood cells, leukemia cells don’t die when they become old or damaged, so they can build up and crowd out normal blood cells. The resulting low level of normal blood cells can make it harder for the body to get oxygen to tissue, control bleeding, and fight infections. Leukemia cells also can spread to other organs, such as the lymph nodes, spleen, and brain. There is no cure for leukemia, but it may be treated with chemotherapy, targeted drug therapy, radiation, or stem cell transplant.

Acute leukemia usually develops quickly and tends to cause fatigue, easy bruising, and frequent infections. Chronic leukemia usually develops slowly, with the leukemia cells working almost as well as normal white blood cells. Patients may not feel sick at first, but if not treated the leukemia cells may later crowd out normal blood cells. Leukemias also are named for the type of white blood cell that is affected. Leukemia that starts in myeloid cells is called myeloid, myelogenous, or myeloblasticleukemia. Leukemia that starts in lymphoid cells is called lymphoid, lymphoblastic, or lymphocyticleukemia. The four most common types of leukemia are acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), chronic myeloid leukemia (CML), and chronic lymphocytic leukemia (CLL).