Objective: To assess the prognostic value of both morphological persistent disease on day 19, on complete remission (CR) and minimal residual disease (MRD) in the bone marrow (BM) after multiagent remission induction therapy.
Methods: From January 1998 to May 2003, 193 patients with newly diagnosed ALL were enrolled on protocol of ALL-XH-99. BM blast counts on day 19 and on CR after induction therapy were examined. BM MRD at the end of induction therapy was detected by MP-FCM.
Results: (1) The probability of 5-year event-free survival (pEFS) was significantly worse for patients with > or = 0.050 BM lymphoblasts on day 19 than that with < 0.050 BM lymphoblasts [(42.59 +/- 14.28)% vs (74.24 +/- 6.67)%, P < 0.001]. (2) The 5-year pEFS was significantly worse for patients with a low percentage of lymphoblasts (< 0.050) in BM on CR as compared to those with no morphological persistent lymphoblasts [(63.47 +/- 9.23)% vs (76.41 +/- 6.09)%, P < 0.05]. (3) No significant difference was found in BM lymphoblasts between patients with MRD (> or = 10(-4) of nucleated bone marrow cells) and those without MRD (< 10(-4)) at the end of induction therapy (P > 0.05). The 22-month pEFS was significantly worse for patients with MRD as compared with those without MRD on CR [(23.81 +/- 20.26)% vs (94.44 +/- 5.40)%, P = 0.001].
Conclusions: BM lymphoblast > or = 0.050 on day 19 after induction therapy is an independent prognostic factor for childhood ALL; low percentage of lymphoblasts and minimal residual disease in BM on remission also do it. Patients with > or = 0.050 lymphoblast in BM on day 19 or with MRD > or = 10(-4) at the end of induction therapy should receive altered and more intensive chemotherapy.