Researchers identified small nucleolar RNAs (snoRNAs) as potential blood biomarkers for radiation-induced senescence in glioblastoma, the most aggressive brain cancer. Using patient-derived cell cultures, they found that radiation exposure triggers senescence rather than cell death, with senescent cells releasing extracellular vesicles enriched with specific snoRNAs including SNORA49. This signature was conserved across 4 of 5 glioblastoma models and confirmed in breast cancer cells. Preliminary analysis of plasma from four glioblastoma patients showed detectable increases in senescence-associated RNAs post-treatment. This finding addresses a critical clinical gap in cancer treatment. Radiation-induced senescence creates therapy-resistant tumor cells that fuel recurrence, yet current methods to detect senescence require invasive brain biopsies. A blood-based biomarker could revolutionize patient care by identifying who would benefit from senolytic drugs that eliminate senescent cells. However, the study's limitations include small patient cohort size and preliminary validation. The mechanistic insight that snoRNAs are packaged with their binding proteins rather than randomly released suggests a controlled cellular process. This work represents an incremental but potentially impactful advance toward personalized neuro-oncology treatments.