Prognostic discrimination for early chronic phase chronic myeloid leukemia in imatinib era: comparison of Sokal, Euro, and EUTOS scores in Korean population

Beyond the conventional Sokal and Euro scores, a new prognostic risk classification, based on the European Treatment Outcome Study (EUTOS), has been developed to predict the outcome of treatment with tyrosine kinase inhibitors (TKI) in chronic myeloid leukemia (CML). In the present study, each risk score was validated by various endpoints in 206 Korean patients with early chronic-phase CML treated with up-front standard dose imatinib. In our analysis, all three scores were found to be valid. The 5-year event-free survival (EFS) was significantly discriminated using Sokal (P = 0.002), Euro (P = 0.003), and EUTOS (P = 0.029), with the worst probability by Euro high-risk (62 vs. 49 vs. 67 %) and better EFS in Sokal low-risk (89 vs. 86 vs. 82 %). Combining all scores identified 6 % of all patients having homogeneous high-risk with distinctively worse outcomes (5-year EFS of 41 %, cumulative complete cytogenetic response rate of 56 %, and cumulative major molecular response rate of 27 %), whereas the group of discordance in risk scores (60 %) had similar results to those of intermediate-risk groups of Sokal and Euro scores. Combining all risk scores for baseline risk assessment may be useful in clinical practice for identifying groups of patients who may benefit from treatment initiation with a more potent TKI among the currently available first-line TKIs.