Detection of minimal residual disease in B‐lineage acute lymphoblastic leukaemia by quantitative flow cytometry

The clinical significance of detecting minimal residual disease (MRD) in B‐lineage acute lymphoblastic leukaemia (ALL) was evaluated by quantitative flow cytometry using a combination of TdT with CD10 and CD19. 53 patients with B‐cell precursor ALL were followed during and after completion of treatment (median follow‐up 23 months). Nine patients relapsed and MRD had been detected in six of them, 5–15 weeks before relapse despite morphological complete remission. 43 patients remain in clinical remission and in none of these was MRD detected. Disease‐free survival based on the detection of MRD by flow cytometry showed a statistically significant difference between both groups (P