Abstract: Objective To retrospectively analyze the value of early treatment response to assess prognosis of children with acute lymphoblastic leukemia (ALL). Methods Two hundred and twenty newly diagnosed ALL patients from April 2015 to December 2019 were included in this study. CCCG-ALL 2015 regime was given to these patients. Bone marrow cytology and minimal residual disease were detected to evaluate the early treatment response on the Day 19 and Day 46 after induction treatment. Results A total of 92 females and 128 males were enrolled in this study. The median age was 5 . 1 years, and the median follow-up time was 45 months. The induced remission rate was 97 . 7 %, the long-term survival rate was 94 . 6 %, the mortality rate was 5 . 4 %, and the recurrence rate was 6 . 8 %. The 5 -year cumulative recurrence rate was ( 9 . 4 ± 2 . 4 )%, and the median recurrence time was 32 months. The 5 -year EFS was ( 87 . 5 ± 2 . 6 )%, and the 5 -year OS was ( 92 . 7 ± 2 . 2 )%. The difference among three groups (low-risk group, medium risk group and high-risk group) was statistically significant (P< 0 . 05 ). The 5-year EFS rate of MRD-negative and positive groups on day 19 of induced therapy were (94.4±3.5)% and (82.5±3.9)%, respectively, the differences were statistically significant (P< 0 . 05 ). In the MRD positive group, differences among the 5 -year EFS rate of MRD 0 . 01 %~ 0 . 099 %, 0 . 1 %~ 0 . 99 %, and ≥1 % groups were ( 93 . 5 ±3 . 8 )%、( 80 . 9 ± 7 . 1 )% and ( 64 . 1 ± 10 . 3 )% respectively, which showed statistical significance (P<0.001). Multivariate analysis showed that MRD≥1% on day 19 (HR= 7 . 04 , 95 %CI: 2 . 84 - 17 . 46 ) and MRD≥ 0 . 01 % on day 46 (HR=1.67, 95%CI: 1 . 17 - 2 . 37 ) were independent risk factors for the prognosis of EFS. Conclusion The overall efficacy of acute lymphoblastic leukemia in children was satisfied, with high induction remission rate, and the recurrence rate of the children with D 19 MRD< 0 . 01 % was low. MRD≥ 1 % on Day 19 and MRD≥ 0 . 01 % on Day 46 are poor factors affecting the prognosis of childhood ALL.

Key words: acute lymphoblastic leukemia; event-free survival; prognosis; child