Leukemia is a malignant neoplasm of the blood-forming tissues. It is characterized by an abnormal increase in the number of leukocytes (white blood cells) in the blood and bone marrow, and by the infiltration of other organs by these cells. The four main types of leukemia are acute lymphocytic leukemia, chronic lymphocytic leukemia, acute myeloid leukemia, and chronic myeloid leukemia.
There are several risk factors for developing leukemia. These include exposure to ionizing radiation, certain chemicals (such as benzene), certain viral infections (such as HIV/AIDS), and a family history of the disease. Treatment for leukemia may include chemotherapy, radiation therapy, stem cell transplantation, and targeted therapy.
The prognosis for patients with leukemia varies depending on the type of leukemia and the stage at which it is diagnosed. In general, however, the survival rates for all types of leukemia have increased significantly over the past few decades due to advances in treatment options.