Leukemia (American English) or leukaemia (British English) is a group of cancers that usually begins in the bone marrow and results in high numbers of abnormal white blood cells. These white blood cells are not fully developed and are called blasts or leukemia cells. Symptoms may include bleeding and bruising problems, feeling very tired, and an increased risk of infections. These symptoms occur due to a lack of normal blood cells. Diagnosis is typically by blood tests or bone marrow biopsy.
The exact cause of leukemia is unknown. Different kinds of leukemia are believed to have different causes. Both inherited and environmental (non-inherited) factors are believed to be involved. Risk factors include smoking, ionizing radiation, some chemicals (such as benzene), prior chemotherapy, and Down syndrome. People with a family history of leukemia are also at higher risk. There are four main types of leukemia: acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL) and chronic myeloid leukemia (CML), as well as a number of less common types. Leukemia is part of a broader group of neoplasms which affect the blood, bone marrow, and lymphoid system, known as tumors of the hematopoietic and lymphoid tissues.
Treatment may involve some combination of chemotherapy, radiation therapy, targeted therapy, and bone marrow transplant, in addition to supportive care and palliative care as needed. Certain types of leukemia may be managed with watchful waiting. The success of treatment depends on the type of leukemia and the age of the person. The average five-year survival rate is 57% in the United States. In children under 15, the five-year survival is greater than 60 to 85%, depending on the type of leukemia. In people with acute leukemia who are cancer-free after five years, the cancer is unlikely to return.
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- Leukemia at Wikipedia. Retrieved September 30, 2014.