Background: Glioblastoma (GBM) is the most common and aggressive type of tumor arising from the central nervous system. GBM remains an incurable disease despite current advancement in therapies, with survival rates of approximately 15 months. Recent literature has highlighted that GBM can release tumoral content which crosses the blood-brain barrier (BBB) and as a consequence can be detected in patients' blood, such as circulating tumor cells (CTCs). CTCs carry tumor information and have shown promise as prognostic and predictive biomarkers in other cancer types. Currently, the prognostic utility of CTCs in GBM is not well understood.

Methods: Blood samples from GBM patients (n=18) attending a tertiary referral hospital were collected before and after surgery to investigate the prognostic role of CTCs. CTCs were isolated using spiral microfluidic technology and characterized using immunofluorescence for GFAP, cell surface vimentin and CD45, in addition to fluorescence in situ hybridization (FISH) to detect EGFR amplification. CTC counts of patients with poor outcomes (recurrence or death) versus patients with good outcomes (stable disease and no recurrence) were compared using a negative binomial distribution.

Results: CTCs were found in 12 out of 18 patients (66.7%), 8/18 before surgery and 10/17 after surgery. CTC clusters were found in 2 patients. CTCs counts before surgery were significantly higher for patients with poor clinical outcome (p=0.0396).

Conclusion: Our preliminary data support the use of this spiral technology to isolate CTCs. CTCs and CTC clusters can be used as prognostic biomarkers for managing GBM patients.