The level of minimal residual disease is an important prognostic factor in childhood acute lym- phoblastic leukaemia. The end of induction therapy is the most significant time-point for predicti- on of treatment outcome. Within a pilot study covered by the Paediatric Haematology Working Group in the Czech Republic 51 childhood patients were analysed at diagnosis of acute lymphob- lastic leukaemia and at the end of induction using method based on detection of clonal rearrange- ments of immuno-receptor genes. The majority of tested patients (32/51, 63 %) had a low or non-detectable levels of residual disease, a group of patients with the highest levels and thus the highest risk of relapse included 10% of patients (5/51). Within each of three risk groups one patient has relapsed so far. Therefore, the relapse rate in particular subgroups is 3 % (1/32), 7 % (1/14) and 20 % (1/5) to date, respectively. The results are compared with these published by the BFM group (van Dongen et al., Lancet 1998). The pilot phase of a new BFM treatment protocols includes examination of residual disease for stratification of patients into the different risk groups.

        Key words: Childhood acute lymphoblastic leukaemia - Minimal residual disease - Prognosis -