Considering all events, with a median observation time of 60 (1-83) months, the estimated 6-year outcome resulted inferior for older patients (Kaplan-Meier method). Censoring the deaths unrelated to CML progression (in chronic phase and in complete hematologic response at the time of death) no difference was observed in the estimated 6-year outcome between older and younger patients (Kaplan-Meier method).

EFS indicates event-free survival; FFS, failure-free survival; PFS, progression-free survival; OS, overall survival; CML, chronic myeloid leukemia; ELN, European LeukemiaNet; CHR, complete hematologic response; CyR, cytogenetic response; PCyR, partial CyR; CCyR, complete CyR; AP/BP, accelerated phase/blast phase; CCA, clonal cytogenetic abnormalities; Ph+, Philadelphia positive; and IM, imatinib.

All analyses were performed according to the intention-to-treat principle

EFS, FFS, PFS, and OS were calculated from the date of the first imatinib dose until any event (EFS), until failure (FFS), until progression to AP/BP or death (PFS), and until death (OS). Treatment failures were defined according to the updated ELN recommendations²⁵ : No CHR at 3 months, no CyR at 6 months, < PCyR at 12 months, < CCyR at 18 months, loss of CHR or CCyR or progression to AP/BP, occurrence of CCA in Ph+ cells (CCA/Ph+), occurrence of mutation poorly sensitive to imatinib at any time, and death. Events were defined as: treatment failure or permanent discontinuation of IM for any reason (including toxicity, patient refusal or loss to follow-up, and death).