Objective: In preparation of a randomized controlled trial, the investigators aim to assess pilot data on technical feasibility and safety of laser interstitial thermal therapy (LITT) at Radboud University Medical centre and to assess practical feasibility of a randomized study in patients with primary irresectable glioblastoma, as compared with standard of care.

Study design: Prospective randomized pilot study. Randomization stopped (amendment September 2nd, 2021),

Study population: 20 patients aged >= 18 with radiologically suspected diagnosis of primary glioblastoma and contra-indication for surgical resection.

Intervention: Patients will be randomized to receive either (i) biopsy and LITT (n=10) or (ii) biopsy alone (n=10).

Inclusion criteria

In order to be eligible to participate in the study, a patient must meet all of the following criteria:

• Informed consent, age >18-year-old
• Supratentorial localization
• Maximal volume <=70cc on post-contrast T1 MRI
• Safe trajectory/trajectories possible for ablation of 70% of the tumour, avoiding eloquent structures or transgression of a ventricle or vessel .
• Karnofsky Performance Status (KPS) >= 70

Exclusion criteria

A potential subject who meets any of the following criteria will be excluded from participation in this study:

• Contra-indication for general anaesthesia or MRI
• Lesion >70cc on post-contrast MRI on the day before intervention.
• Non-glioblastoma diagnosis as per frozen section analysis
• Pregnancy