Acute forms of leukemia include acute myeloid leukemia, a rapidly progressing cancer that begins in blood-forming tissue such as the bone marrow and causes large numbers of blood cells to be produced and enter the bloodstream; and acute lymphoblastic leukemia, also known as lymphoblastic lymphoma, in which lymph nodes are involved rather than the blood and bone marrow. Acute myeloid leukemia is one of the most common forms of leukemia in adults; it is rare in persons under the age of 40, generally occurring around age 65, and is more common in men than women. Acute myeloid leukemia also can occur in children of any age, with girls and boys being affected equally. Increased risk for the development of this cancer is associated with exposure to radiation and chemicals, immunosuppression, and certain hematologic disorders, as well as genetic factors. Each type of leukemia has its own characteristics and treatment. Options for patients with acute leukemia, which is often curable, include chemotherapy, biologic therapy, radiation, and stem cell or bone marrow transplantation.