A population-based analysis of the molecular landscape of glioma in adolescents and young adults reveals insights into gliomagenesis.

Gliomas are a major cause of cancer-related deaths in adolescents and young adults (AYAs; ages 15-39 years). Different molecular alterations drive gliomas in children and adults, leading to distinct biology and clinical consequences, but the implications of pediatric- versus adult-type alterations in AYAs are unknown. Our population-based analysis of 1,456 clinically and molecularly characterized gliomas in patients aged 0-39 years addresses this gap. Pediatric-type alterations were found in 31% of AYA gliomas and conferred superior outcomes compared to adult-type alterations. AYA low-grade gliomas with specific RAS-MAPK alterations exhibited senescence, tended to arise in different locations and were associated with superior outcomes compared to gliomas in children, suggesting different cellular origins. Hemispheric IDH-mutant, BRAF p.V600E and FGFR-altered gliomas were associated with the risk of malignant transformation, having worse outcomes with increased age. These insights into gliomagenesis may provide a rationale for earlier intervention for certain tumors to disrupt the typical behavior, leading to improved outcomes.