Treatment stratification based on initial in vivo response in acute myeloid leukaemia in children without Down's syndrome: results of NOPHO‐AML trials

Three consecutive protocols for childhood acute myeloid leukaemia (AML) have been used in the Nordic countries since 1984: the Nordic Society for Paediatric Haematology and Oncology (NOPHO)‐AML84 was of moderate intensity, NOPHO‐AML88 of high intensity with upfront loading and aggressive consolidation. NOPHO‐AML93 utilized the same treatment blocks as NOPHO‐AML88, but after the first block those children with a hypoplastic non‐leukaemic bone marrow were allowed to recover from aplasia. Poor responders received intensified induction therapy. Between January 1993 and December 2000, 219 children without Down's syndrome were entered on NOPHO‐AML93. Compared with NOPHO‐AML88, the event‐free survival (EFS) at 7 years increased from 41% to 49% (P = 0·06) and 7‐year overall survival increased from 47% to 64% (P