Fluorescent marker could improve brain surgery outcomes

07 November 2018

A fluorescent chemical that highlights the most aggressive cancer cells can be used to help surgeons remove brain tumours and improve patient outcomes.
Georgina Hines

‘Gliomas are difficult to treat with survival times often measured in months rather than years. Many patients are treated with surgery and the aim is to safely remove as much of the cancer as possible,’ explained Dr Kathreena Kurian, a consultant neuropathologist and Reader in Brain Tumour Research at the University of Bristol, UK.

Glioma is the most common form of brain cancer, responsible for 30% of all brain tumours. Surgery remains a common treatment, with 50% of low-grade patients requiring surgery after two to three years. However, surgeons find it difficult to differentiate between cancerous and healthy brain tissue and surgery is therefore not always successful.

Now, a cross-university team, including Dr Kurian, have presented evidence that shows a fluorescent marker – 5-aminolevulinic acid (5-ALA) – accumulates in fast-growing cancer cells, highlighting high-grade cells, and improving surgical outcomes.

‘Once a tumour is removed, it is passed on to a pathologist who examines the cells under a microscope to see if they are ‘high-grade’, fast growing cells, or ‘low-grade’ slower growing cells. And we can plan further treatment, such as radiotherapy or chemotherapy, based on that diagnosis,’ said Dr Kurian.

‘We wanted to see if using a fluorescent marker could help surgeons objectively identify high-grade tumour cells during surgery, allowing them to remove as much cancer as possible while leaving normal brain tissue intact,’ she said.

Ninety-nine patients underwent surgery as part of the study and all were expected to have high-grade tumours. Surgeons reported seeing fluorescence in 85 of the patient’s tumours; 81 of which were confirmed to have high-grade cells after testing by pathologists. The remaining 14 tumours were either confirmed to have low-grade cells or could not be evaluated.

‘Neurosurgeons need to be able to distinguish tumour tissue from the other brain tissue, especially when the tumour contains fast-growing, high-grade cancer cells,’ said Professor Colin Watts, Chair of the Brain Cancer Program at the University of Birmingham, UK.

‘This is the first prospective trial to show the benefits of using 5-ALA to improve the accuracy of diagnosing high-grade glioma during surgery. These results show that the marker is very good at indicating the presence and location of high-grade cancer cells,’ he said.

The team aims to continue with research into other markers that can be used to highlight low-grade cancer cells and ways to distinguish between tumours and scar tissue for those with recurring brain cancers.

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