Risk stratification
Patients were enrolled in the high risk (HR) group if they had an initial white blood cell (WBC) count of > 50 000/ul, were aged < 1 year or > 10 years, had initial CNS-involvement, had a mediastinal mass on the initial chest x-ray, had more than 1000 lymphoblasts/mm3 in the peripheral blood after the first week of monotherapy or no remission in the bone marrow after induction on day 36. All other patients were stratified into the SR group (table 2). The main differences in the treatment between the two groups were additional applications of daunorubicin during induction and maintenance and higher doses of cytarabine in the intrathecal therapy during induction, consolidation and maintenance in the HR group.