Butterfly glioblastomas (bGBM), defined as tumours crossing the midline to involve hemispheres bilaterally, have a dismal prognosis with a median survival of 3.3-6 months and only 9% of patients with bGBM survive 2-years. These figures put bGBM in the worst end of the spectrum of GBM prognosis, significantly inferior to the survival figures quoted in the literature with standard of care - 14.6 months - particularly when 5-aminolevulinic acid is used as surgical adjuvant - 17.47 months.

Despite the poor outcome of this disease, there is preliminary evidence suggesting that active oncology treatment can impact the survival of patients with this condition.With particular regards to surgical resection versus biopsy, there is a suggestion that resection improves overall survival at 6 months with no clear difference at 12 and 18 months of follow up.

Laser-induced thermal therapy (LITT) is a minimally invasive laser ablation technique used in a range of brain tumours, including glioblastomas, with similar overall survival to the ones reported for open surgery in patients with lesions not amenable to open resection. The minimally invasive nature of this technique, significantly reducing the collateral damage to the surrounding brain structures, suggests Its potential in the treatment of this bGBM [14] with significant implications as a deficit-sparing technique, particularly if associated with preoperative and intraoperative monitoring and mapping techniques.

The SLITT-GBM study will combine unilateral open surgery for maximal tumour resection with contralateral LITT to the smaller component/residual.

Inclusion Criteria:

1. Presumptive diagnosis of bGBM as per preoperative MRI and MDT assessment
2. Presumed residual / smaller component of the bGBM has to be < 2.5cm
3. Performance Status 0-1
4. Able to consent for the study

Exclusion Criteria:

1. bGBM measuring >2.5 cm in both hemispheres.
2. Tumour progression between surgical debulking and LITT treatment
3. Severe complications after surgery (hydrocephalus, infection, heamatoma, stroke)