The European Treatment and Outcome Study score is associated with clinical outcomes and treatment response following European LeukemiaNet 2013 recommendations in chronic-phase chronic myeloid leukemia.

The introduction of tyrosine kinase inhibitors has dramatically improved outcomes for many patients with chronic myeloid leukemia (CML), but some cases are resistant to this treatment. To compare the prognostic performance of Sokal, Hasford, and European Treatment and Outcome Study (EUTOS) scores, patient outcomes and treatment responses were investigated following the European LeukemiaNet (ELN) 2013 recommendations. Seventy-three patients with newly diagnosed chronic-phase CML (CML-CP) treated with any tyrosine kinase inhibitor as initial therapy were analyzed. All scoring systems significantly predicted treatment response at 3 and 6 months; however, only the EUTOS score significantly predicted treatment response at 12 months, following the ELN 2013 recommendations. The 5-year event-free survival rates were 93 and 35 % in the low- and high-risk groups according to the EUTOS score (P < 0.0001). Moreover, the 5-year overall survival rates were 98 and 51 % in the low- and high-risk groups by EUTOS score (P < 0.0001). We suggest that the EUTOS score may provide a better stratification of CML-CP patients for predicting treatment response.