A technique to make brain tumours glow, helping surgeons to operate, is being tested in the UK.
Patients will be given a drug which causes a build-up of fluorescent chemicals in the tumour, making it glow pink.
It will mark the edges of the tumour more clearly, making removal easier.
More than 60 patients with glioblastoma, the most common and harmful malignant brain tumour for adults, are taking part in the trial.
In some cancers, such as those of the colon, some of the surrounding tissue can be removed as well as the tumour. But removing a brain tumour needs to be more precise as "functional tissue" needs to be protected.
Funded by Samantha Dickson Brain Tumour Trust (SDBTT) and Cancer Research UK, the GALA-5 trial of the drug 5-amino-levulinic will test the feasibility of extending the availability of the pioneering technique.
Dr Colin Watts, from Cambridge University, is leading the research.
He said: "I strongly feel that our best opportunity to progress further is to emphasise funding of lab-based research and innovative trials, and the GALA-5 trial is a significant step forward in making this a reality.
"I am delighted to see this partnership between Samantha Dickson Brain Tumour Trust and Cancer Research UK, which really makes a difference and allows more trials and clinicians to be supported."
Charles Meacock, 56, from Norfolk, who has already taken part in the trial, said: "Hopefully it will benefit me, but will also help people in my situation in the future."