Leukemia (British spelling: leukaemia) is cancer of the blood or bone marrow (which produces blood cells). A person who has leukemia suffers from an abnormal production of blood cells, generally leukocytes (white blood cells). People sometimes confuse leukemia and lymphoma.Leukemia is a cancer of the blood, lymphoma is cancer of the lymphatic system (lymph glands). The word Leukemia comes from the Greek leukos which means white and aima which means blood. The DNA of immature blood cells, mainly white cells, becomes damaged in some way. person who has leukemia suffers from an abnormal production of blood cells, generally leukocytes (white blood cells). People sometimes confuse leukemia and lymphoma. Leukemia is a cancer of the blood, lymphoma is cancer of the lymphatic system (lymph glands).