NFB-23. Extent of tumor but not location may be predictive of longitudinal disease severity in children with NF1-associated gliomas requiring treatment

BACKGROUND: Children with Neurofibromatosis Type 1 (NF1) are at risk for developing gliomas in multiple locations, particularly the optic pathway and brainstem. The goal of this study is to determine if glioma location in NF1 impacts tumor progression and accumulation of neurological deficits over time. METHODS: Retrospective chart review of 98 pediatric patients with NF1-associated gliomas between 1999-2021 at St. Louis Children’s Hospital. Patients who had never received treatment were excluded from analysis. Each glioma was categorized into one of four locations: posterior fossa (PF, n=12, 21%), supratentorial midline (SM, n=33, 57%) supratentorial cortical (SC, n=4, 7%), brainstem (BS, n=9, 15%). Patients with gliomas in different locations had each tumor counted separately (58 total gliomas analyzed). RESULTS: No SC tumors progressed. Time to first progression was comparable across the other 3 locations, and there was no meaningful different in neurologic deficits over time by tumor location. The majority of patients who demonstrated three or more clinical or radiographic progressions had tumors in the SM region. Within the SM tumor group, each tumor was further characterized as a deep extensive glioma (DEG; 36%) or an optic pathway glioma without deep extension (nonDEG; 64%). DEG had a slightly higher number of neurological deficits at baseline (DEG 2.08, nonDEG 1.19), fewer patients with no neurologic deficits (8.3% DEG vs 28.6% nonDEG) and a higher proportion of patients with a first progression event (41% DEG vs 24% nonDEG). However, DEG and nonDEG had similar risk of subsequent progressions after the initial event. CONCLUSION: Among children with NF1 who required glioma treatment, location was not a significant predictor of multiple progression or neurologic morbidity over time. Within the SM location, DEGs represent a newly characterized group that exhibit potentially higher rates of progression and neurological deficits. Multi-institutional analysis is needed to confirm these findings.