Clinical and genomic factors differ in pediatric and adult pilocytic astrocytoma: a single-center experience with over 350 patients.

Purpose: Pilocytic astrocytoma (PA) is rare in adults despite being the most common pediatric brain tumor. KIAA1549::BRAF fusion and BRAF p.V600E mutation are common in PA, yet prognostic impact of these alterations remains uncertain. We highlight clinical characteristics and tumor genomics in PA across the lifespan, exploring factors associated with disease progression.

Methods: Pediatric and adult patients who underwent biopsy or resection of PA from 2000 to 2023 were retrospectively studied. Clinical data and tumor genomics were collected, and progression/recurrence-free survival (PRFS) analysis was performed.

Results: We identified 334 pediatric and 32 adult PA patients. Tumor location distribution did not differ between groups, with the cerebellum being the predominant location (59.3% pediatric and 50.0% adult). Gross total resection (GTR) was more common in children (79.1% versus 62.1%, p = 0.04). KIAA1549::BRAF fusion was more frequent in children (59.6% versus 23.1%, p = 0.02). BRAF p.V600E mutations were rarer in both groups (14.6% pediatric versus 8.3% adult, p = 1). In children, GTR was associated lower rates of tumor progression/recurrence (9.8% versus 41.2%, p < 0.001) and longer PRFS (p < 0.001). Cerebellar tumors in children were also associated with lower rates of tumor progression/recurrence (13.1% versus 31.6%, p < 0.001) and longer PRFS (p < 0.001). No operative/genomic predictors of PRFS were identified in adults. Overall rate of tumor progression/recurrence did not differ between groups (21.3% pediatric versus 15.6% adult, p = 0.65).

Conclusion: Clinical characteristics and factors influencing tumor progression/recurrence differ in children and adults with PA. This work highlights current knowledge gaps on age-related differences in PA, providing clinical and genomic context for future studies.