Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Accelerated phase chronic myelogenous leukemia is a phase of chronic myelogenous leukemia in which the disease is progressing. In this phase, 6% to 30% of the cells in the blood and bone marrow are blast cells (immature blood cells). Prognosis is very poor once chronic myelogenous leukemia reaches the accelerated phase-it behaves simalary to acute myeloid leukemia. Chronic myelogenous (or myeloid) leukemia (CML), also known as chronic granulocytic leukemia (CGL), is a cancer of the white blood cells.