Patients will be given a drug, 5-amino-levulinic acid (5-ALA), which causes a build-up of fluorescent chemicals in the tumour. The theory is that the pink glow will clearly mark the edges of the tumour, making it easier to ensure all of it is removed. More than 60 patients with glioblastoma will take part in the trial. They have cancerous glial cells, which normally hold the brain’s nerves cells in place. On average patients survive 15 months after being diagnosed.