Prognostic value of minimal residual disease in relapsed childhood acute lymphoblastic leukaemia

Molecular monitoring by quantitative PCR techniques of residual leukaemia c ells during the first phases of treatment can predict outcome in children w ith acute lymphoblastic leukaemia. We did a retrospective study of 30 child ren who had been treated according to the ALL-REZ BFM trials to assess whet her amount of minimal residual disease during the first stages of treatment for relapsed acute lymphoblastic leukaemia could predict outcome. In child ren with minimal residual disease of less than 10(-3) at day 36, probabilit y of event-free survival was 0.86 (95% CI 0.77-0.95), compared with 0 in ch ildren with minimal residual disease of 10(-3) or greater (p<0.001). Our re sults suggest that information about molecular response to treatment can be used to predict longterm outcome in relapsed childhood acute lymphoblastic leukaemia.