Survival in patients with Acute Lymphoblastic Leukemia, treated with the Total XV chemotherapy protocol: A Structural Equation Model

Background: Acute lymphoblastic leukemia (ALL) is the most common neoplasm of childhood. Survival depends on a series of risk factors (RF) that have not been jointly assessed. This study aimed to identify a joint predictive model for disease-free survival (DFS) and overall survival (OS) in patients with ALL treated with the Total XV chemotherapy protocol. Methods: : Retrospective cohort study of 1 to 14 years old children, treated in 2006-2020 for ALL with the Total XV chemotherapy protocol in an Ecuadorian cancer center. Bio demographic, clinical, immunophenotype, translocations (t), response to treatment (RTT), DFS and OS were studied. Analyses included descriptive statistics and predictive structural equations, using global adjustments (X 2 , CFI and RMSEA) and path incorporation/elimination (Lagrange and Wald test). Results: : Of the 144 children (54.9% male) studied: 27.8% had infiltration of the Central Nervous System (CNS); 43.1% were low risk; 4.2% presented t(9-22), and 95.8% were immunophenotype B. Negative minimal residual disease (MRD) on days 15 and 42 of the induction phase was 43.8% and 77.1 % respectively. Induction mortality was 9%. DFS and OS was 45% and 75.7% at 111 and 144 months, respectively. Patients with CNS infiltration, high risk and positive MRD on days 15 and 42, had lower DFS and OS (p0.05). Adjustment indicators corroborated the results (CFI 0.91 and RMSEA 0.04). Conclusion: CNS infiltration, high risk, and positive MRD are RF, which jointly explain DFS and OS in patients with ALL treated with the Total XV chemotherapy protocol.