Blast phase

Refers to advanced chronic myelogenous leukemia. In this phase, the number of immature, abnormal white blood cells in the bone marrow and blood is extremely high. Also called blast crisis.

The phase of chronic myelogenous leukemia in which more than 30% of the cells in the bone marrow or blood are blast cells (immature, abnormal white blood cells). When tiredness, fever, and an enlarged spleen also occur, it is called blast crisis.