Risk Factors for Relapse of Childhood B Cell Acute Lymphoblastic Leukemia.

BACKGROUND B cell acute lymphoblastic leukemia (B-ALL) is the most common type of ALL. This study aimed to explore risk factors for relapse of childhood B-ALL. MATERIAL AND METHODS Total of 102 pediatric B-ALL patients were included in this study. B-ALL patients were divided into a relapse group and a non-relapse group. Chemotherapy-induced agranulocytosis time, fusion gene, and minimal residual disease (MRD) were assessed. White blood cell (WBC) count in peripheral blood and risk stratification were evaluated in newly-diagnosed patients. Kaplan-Meier plots were used to evaluate the correlation between risk factors and relapse rates. Multivariate analysis was performed with Cox proportional hazard model to estimate relative risk (RR), 95% confidence interval (95% CI), and hazard ratio (HR). Finally, 99 cases of B-ALL were included in this study. RESULTS There were significant differences between the relapse group and the non-relapse group in age (p=0.004), chemotherapy-induced agranulocytopenia (p=0.001), WBC count in peripheral blood of newly diagnosed patients (p=0.016), risk stratification (p=0.000), and MRD at 12th week (p=0.007). Age over 10 years, high-risk stratification, long period of agranulocytopenia, higher WBC counts, and MRD more than 10⁻⁴ were correlated with higher B-ALL relapse rate (p<0.05). Multivariate analysis showed significantly higher relapse rates for age ≥10 years, high-risk stratification, and MRD at 12th week >10⁻⁴, with RR (95% CI) of 4.001 (1.005-15.930), 4.964 (1.050-23.456), and 4.646 (1.383-15.614), respectively. CONCLUSIONS Agranulocytopenia ≤7 days, peripheral blood WBC >100×10⁹/L, and MRD at 33rd day >10⁻⁴ were associated with B-ALL relapse. Age ≥10 years, high-risk stratification, and MRD at 12th week >10⁻⁴ were independent risk factors for relapse.