Table 1

List of the criteria for the definition of AP and BP, as recommended by ELN4,5 and by the World Health Organization6

Accelerated phaseDefinition
 ELN criteriaBlasts in blood or marrow 15-29%, or blasts plus promyelocytes in blood or marrow >30%, with blasts <30%
Basophils in blood ≥20%
Persistent thrombocytopenia (<100 × 109/L) unrelated to therapy
Clonal chromosome abnormalities in Ph+ cells (CCA/Ph+), major route, on treatment
 WHO criteriaBlasts in blood or marrow 10-19%
Basophils in blood ≥20%
Persistent thrombocytopenia (<100 × 109/L) unrelated to therapy
CCA/Ph+ on treatment
Thrombocytosis (>1000 × 109/L) unresponsive to therapy
Increasing spleen size and increasing white blood cell count unresponsive to therapy
Blast phase
 ELN criteriaBlasts in blood or marrow ≥30%
Extramedullary blast proliferation, apart from spleen
 WHO criteriaBlasts in blood or marrow ≥20%
Extramedullary blast proliferation, apart from spleen
Large foci or clusters of blasts in the bone marrow biopsy
  • The ELN criteria are those that were used in all main studies of TKI. The use of TKI may require a change of the boundaries between CP, AP, and BP and modify to some extent the classic subdivision of CML in 3 phases, but the data are not yet sufficient for a revision.

  • CCA/Ph+, clonal chromosome abnormalities in Ph+ cells.