Outcomes of Pediatric Precursor B Cell Acute Lymphoblastic Leukemia: A Tertiary Care Cancer Center Experience from a Lower-Middle-Income Country.

Introduction: Precursor B-cell acute lymphoblastic leukemia (ALL) is the most common childhood malignancy. While cure rates in high-income countries (HICs) exceed 90%, outcomes in low- and middle-income countries (LMICs) remain suboptimal. This study evaluated treatment outcomes for pediatric pre-B cell ALL patients at a tertiary cancer hospital in an LMIC. Materials and Methods: Pediatric precursor B-cell ALL patients treated at Shaukat Khanum Memorial Cancer Hospital and Research Centre, Pakistan between September 2017 and September 2022 were included. Results: A total of 436 pediatric patients were analyzed, with a median age of 3 years and a male predominance (61.5%). Most patients (96.3%) were classified as standard risk, while CNS and testicular involvement were rare. Among standard-risk patients, 81.8% achieved complete remission, and 17.4% remained minimal residual disease (MRD)-positive after induction. For high-risk patients, 75% achieved complete remission, and 25% remained MRD-positive at the end of induction. In total, 374 patients achieved remission, but 56 (14.9%) relapsed, most often as isolated bone marrow relapse (53.6%). Early relapse was most common. Overall mortality was 26.1%, with induction mortality at 11.7%. Sepsis was the leading cause of death (59.7%), followed by relapse (29%). Five-year overall survival (OS) and event-free survival (EFS) were 75.8% and 66.4%, respectively. Conclusion: Our study demonstrates good outcomes for pediatric precursor B-cell ALL in a resource-limited LMIC setting. Sepsis and relapse were the main causes of mortality.