List of the criteria for the definition of AP and BP, as recommended by ELN4,5 and by the World Health Organization6
| Accelerated phase | Definition |
| ELN criteria | Blasts 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 criteria | Blasts 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 criteria | Blasts in blood or marrow ≥30% |
| Extramedullary blast proliferation, apart from spleen | |
| WHO criteria | Blasts in blood or marrow ≥20% |
| Extramedullary blast proliferation, apart from spleen | |
| Large foci or clusters of blasts in the bone marrow biopsy |
| Accelerated phase | Definition |
| ELN criteria | Blasts 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 criteria | Blasts 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 criteria | Blasts in blood or marrow ≥30% |
| Extramedullary blast proliferation, apart from spleen | |
| WHO criteria | Blasts 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.