QLTI-26. Analysis of initial treatment patterns for pediatric central nervous system neoplasms across evolving WHO classifications: a single-institution cohort study

Abstract BACKGROUND The management of pediatric central nervous system (CNS) neoplasms has historically been surgical resection, especially for low-grade tumors. The current therapeutic landscape is evolving as the WHO guidelines shift from a primarily histological to molecular classification. While standard-of-care protocols are established by multi-institutional studies, single-institutional analysis can demonstrate real-world implementation of these evolving treatment strategies. This study characterizes the initial treatment regimens in an institutional cohort of pediatric CNS tumor patients. METHODS A retrospective chart review of patients 8 months-17 years old diagnosed with CNS neoplasms who presented at our institution between January 2013 and June 2023. Patients with unconfirmed pathology were excluded. Data on initial treatment method and WHO year, classification, and grade was analyzed. RESULTS The cohort (N=84, mean age at diagnosis 7.8 years; 50% female) included WHO classifications for 2007 (44.0%), 2016 (39.3%), and 2021 (16.7%). WHO grade was available for 68 patients: Grade I (54.4%), Grade II (8.8%), Grade III (11.8%), and Grade IV (25.0%). Initial treatments included resection-only (79.8%), resection plus radiation (3.6%), resection plus chemotherapy (2.4%), radiation-only (2.4%), chemotherapy-only (2.4%), chemotherapy plus radiation (1.2%), and observation (8.3%). 95.3% of low-grade tumors (WHO Grades I-II) underwent resection-only treatment compared to 76.0% in high-grade tumors (WHO Grades III-IV). Stratification by WHO year showed low-grade tumors had consistently high rates of resection-only treatment (95.0% in 2007, 100% in 2016, and 85.7% in 2021), whereas high-grade tumors had progressive adoption of resection-only treatment (44.4% in 2007, 91.7% in 2016, and 75.0% in 2021). CONCLUSION This cohort analysis reveals distinct initial treatment patterns for pediatric CNS neoplasms, with high resection-only rates for low-grade tumors among classification years and an increase in initial resection-only treatment in high-grade tumors. Despite the limited sample size, this single-institution analysis provides real-world context for understanding the evolving, molecularly-driven therapeutic landscape in pediatric neuro-oncology.