RESUMEN
BACKGROUND: Our aim was to compare two different schedules of maintenance in pediatric acute lymphoblastic leukemia (ALL) treated with a BFM-based therapy, in a randomized study: an Arm with 6-MP + MTX (with or without vincristine and dexamethasone pulses) versus a more intensive continuation phase. PROCEDURE: From January 1996 to November 2002, 429 eligible children with ALL were enrolled in a protocol with BFM-based back-bone, followed by a randomized continuation phase in standard (SRG) and intermediate (IRG) risk groups. Patients were randomized between Arms A and B for SRG and B or C for IRG. Arms A and C consisted of 6-MP and MTX and in Arm C, six pulses of VCR and dexamethasone were added. Arm B combined four pairs of drugs rotated weekly. All risk-groups received maintenance until completing 2 years of therapy from diagnosis. RESULTS: With a median follow-up of 138 (range: 96-178) months, the overall pEFS (SE) was 72 (6)% for all patients and the different risk groups showed: SRG: 85 (3)%, IRG: 71 (1)%, and HRG: 42 (7)% (P-value ≤ 0.0001). The pDFS (SE) according to the assigned arm of maintenance was, for Arm A: 89 (3)% and for Arm B: 85 (4)% in SRG, and, for Arm B: 77 (4)% and for Arm C: 75 (4)% in IRG, at 10 years follow-up. There were no statistically significant differences in outcome between arms of maintenance for both risk groups. CONCLUSIONS: In protocols with initial BFM-based strategy, a more intensive continuation phase did not benefit any risk group of patients.