Leukemia (also spelled leukaemia and pronounced /luːˈkiːmiːə/[1] loo-KEE-mee-ə), is a group of blood cancers that usually begin in the bone marrow and result in high numbers of abnormal blood cells.[9] These blood cells are not fully developed and are called blasts or leukemia cells.[2] Symptoms may include bleeding and bruising, bone pain, fatigue, fever, and an increased risk of infections.[2] These symptoms occur due to a lack of normal blood cells.[2]Diagnosis is typically made by blood tests or bone marrow biopsy.[2]
The exact cause of leukemia is unknown.[5] A combination of genetic factors and environmental (non-inherited) factors are believed to play a role.[5] Risk factors include smoking, ionizing radiation, some chemicals (such as benzene), prior chemotherapy, and Down syndrome.[5][3] People with a family history of leukemia are also at higher risk.[3] 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.[3][10] Leukemias and lymphomas both belong to a broader group of tumors that affect the blood, bone marrow, and lymphoid system, known as tumors of the hematopoietic and lymphoid tissues.[11][12]
Treatment may involve some combination of chemotherapy, radiation therapy, targeted therapy, and bone marrow transplant, in addition to supportive careand palliative care as needed.[3][6] Certain types of leukemia may be managed with watchful waiting.[3] The success of treatment depends on the type of leukemia and the age of the person. Outcomes have improved in the developed world.[10] Five-year survival rate is 57% in the United States.[4] In children under 15, the five-year survival rate is greater than 60% or even 90%, depending on the type of leukemia.[13] In children with acute leukemia who are cancer-free after five years, the cancer is unlikely to return.[13]
In 2015, leukemia was present in 2.3 million people worldwide and caused 353,500 deaths.[7][8] In 2012 it newly developed in 352,000 people.[10] It is the most common type of cancer in children, with three-quarters of leukemia cases in children being the acute lymphoblastic type.[3] However, over 90% of all leukemias are diagnosed in adults, with CLL and AML being most common in adults.[3][14] It occurs more commonly in the developed world.[10]
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| A Wright's stained bone marrow aspirate smear from a person with B-cell acute lymphoblastic leukemia. |
https://en.wikipedia.org/wiki/Leukemia
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