The National Comprehensive Cancer Network updated guidelines to recommend cerebrospinal fluid (CSF)-based molecular tumor profiling for high-grade glioma and glioblastoma when tissue biopsy is not feasible. NCCN’s change supports CSF testing as an adjunctive diagnostic route when patients cannot undergo neurosurgical sampling. Belay Diagnostics said the update backs its Summit 2.0 comprehensive genomic profiling panel, along with Ascent chromosomal instability and Vantage MGMT promoter methylation assays. The tests can be run from a single CSF specimen obtained via standard lumbar puncture. For drug development and clinical decision-making in molecularly driven CNS oncology, the guideline expansion may increase eligible use cases for CSF-based assays and potentially broaden access for patients who previously lacked usable tissue samples.