Prognostic discrimination based on the EUTOS long-term survival score within the International Registry for Chronic Myeloid Leukemia in children and adolescents

The EUTOS Long-Term Survival score was tested in 350 children with chronic myeloid leukemia in first chronic phase treated with imatinib and registered in the International Registry for Childhood Chronic Myeloid Leukemia. With a median follow up of 3 years (range, 1 month to 6 years) progression and/or death (whichever came first) occurred in 23 patients. For the entire cohort of patients the 5-year progression-free survival rate was 92% (95% CI: 87%-94%) and the 5-year survival accounting for chronic myeloid leukemia deaths was 97% (95% CI: 94%-99%). Of the 309 patients allocated to low (n=199), intermediate (n=68) and high (n=42) risk groups by the EUTOS Long-Term Survival score, events (progression and/or death) occurred in 6.0%, 8.8% and 26.2%, respectively. Estimates of the 5-year progression-free survival rates according to these three risk groups were 96% (95% CI: 92%- 98%), 88% (95% CI: 76%-95%) and 67% (95% CI: 48%-81%), respectively. Differences in progression-free survival according to these risk groups were highly significant (P<0.0001, overall). The EUTOS LongTerm Survival score showed better differentiation of progression-free survival than the Sokal (<45 years), Euro and EUTOS scores in children and adolescents with chronic myeloid leukemia and should be considered in therapeutic algorithms.