Whole genome sequencing of spinal fluid DNA may catch brain tumor spread earlier than expected

Researchers studying high-grade glioma — one of the most aggressive forms of brain cancer — are finding that whole genome sequencing (WGS) of circulating tumor DNA (ctDNA) in cerebrospinal fluid (CSF) offers a significant edge over standard targeted sequencing panels. Presented at the 2026 SNO Annual Meeting, findings from NYU's Alexandra M. Miller, MD, showed that WGS not only captured all the mutations detected by next-generation sequencing (NGS) panels, but also picked up additional critical alterations like CDKN2A homozygous deletions and chromosome 7 gain/10 loss.

Perhaps most strikingly, patients with no clinical signs of tumor spread showed completely different mutational signatures in their CSF versus their tumor tissue — suggesting the CSF may be capturing early, pre-symptomatic leptomeningeal disease. In some cases, clonal analysis indicated cancer cells had already seeded the CSF before temozolomide treatment began.

Key Takeaways:

• WGS outperforms targeted NGS panels in detecting copy number alterations and resistance-driving mutations such as hypermutation from temozolomide
• CSF sequencing serves four clinical roles: diagnosis, serial monitoring, understanding tumor biology, and prognosis
• Detectable ctDNA in CSF is a negative prognostic marker that may warrant escalating therapy or more frequent screening

Why it matters: These findings could fundamentally change how clinicians manage high-grade glioma — enabling earlier detection of disease spread and more personalized treatment decisions, even before symptoms emerge.