BACKGROUND : Chronic myeloid leukemia (CML) is a clonal myeloproliferative disorder characterized by a progressive course outlined by the transition from the chronic phase (CP) to blastic crisis (BC). The course of CML-BC is still fatal, and in spite of various efforts in treatment, median survival remains short. The aim of the present study was to analyze the prognostic factors having an impact on response to treatment and survival in patients with CML-BC. We also investigated prognostic influence on survival in myeloid BC according to FAB classification.
METHODS : All patients (N=35) with CML with onset of CML-BC between January 1992 and May 2002 were reviewed.
RESULTS: The median survival for all patients after onset of CML-BC was 7 weeks, and probable survival rate at 24 months was 5.9%. The adverse prognostic factors for survival of CML-BC were high and intermediate risk of Hasford score at diagnosis of CML (P=0.05), normal serum LDH (P=0.016), bone marrow blasts ≥60% (P=0.092), no
treatment at CML-BC (P=0.0056), platelet count <20x10 9 /L (P=0.13). Clonal evolution at diagnosis of CML-BC was associated with a shorter survival. Especially in our study, FAB subtype M4-7 (median survival, 4 weeks; 95% CI, 2~6) had shorter survival duration than M0-2 (median survival, 16 weeks; 95% CI, 5~27) in patients with myeloid CML-BC.
CONCLUSION : The management of patients with CML-BC remains highly unsatisfactory. Once blast crisis has occurred, there are useful parameters to assess the prognosis for the individual patient and these may be of interest in planning therapy. Our experience suggests that FAB classification M4-7 are poor prognostic factor in patients with myeloid CML-BC.

Keywords: Chronic myeloid leukemia, Blastic crisis, FAB classification, Prognosis,