The most common acute leukemia in adults is acute myelogenous leukemia, and the most common chronic leukemia is chronic lymphocytic leukemia, states Mayo Clinic. Although these are the most common types, adults can develop any type of leukemia.
Leukemia is classified into types based on how quickly symptoms develop and what type of cells are affected, reports Mayo Clinic. In acute types, symptoms develop quickly; in chronic types, the affected person may not notice symptoms for months or years. Myelogenous leukemias begin in the myeloid cells, which generate the different types of blood cells. Lymphocytic leukemias develop in lymphoid cells, which become the lymphatic tissue that plays an important role in the immune system. Though the chronic lymphocytic type is more common than the chronic myelogenous type, both types are more frequently found in adults than in children.
Risk factors for leukemia include treatment for prior cancers, certain genetic disorders, some blood disorders, exposure to high levels of radiation and smoking, according to Mayo Clinic. Having one or more of these risk factors does not mean that a person may develop the disease, and many people with leukemia do not have any of the risk factors. Treatment for all types of leukemia involves chemotherapy, biological therapy, targeted therapy, radiation therapy and stem cell transplants.