blastic phase

Definition of blastic phase chronic myelogenous leukemia
National Cancer Institute

blastic phase chronic myelogenous leukemia

(BLAS-tik fayz KRAH-nik MY-eh-LAH-jeh-nus loo-KEE-mee-uh)
A phase of chronic myelogenous leukemia in which 20% or more of the cells in the blood or bone marrow are blast cells (immature blood cells). When tiredness, fever, and an enlarged spleen occur during the blastic phase, it is called blast crisis.

Source: NCI Dictionary of Cancer Terms