Fluorescent marker can help guide surgeons to remove dangerous brain tumour cells more accurately

08 November 2018

A Consultant Neurosurgeon at UHB has led research into the use of a chemical that highlights tumour cells and which can be used by surgeons to help spot and safely remove brain cancer. Details of the trial into its use were presented at the 2018 National Cancer Research Institute (NCRI) Cancer Conference.

The study was led by Professor Colin Watts, Honorary Consultant Neurosurgeon at UHB, Professor of Neurosurgery and chair of the Birmingham Brain Cancer programme at the University of Birmingham.

The research was carried out with patients who had suspected glioma, the disease that killed Dame Tessa Jowell, and the most common form of brain cancer. Treatment usually involves surgery to remove as much of the cancer as possible, which can provide a challenge to identify all of the cancer cells, while avoiding healthy brain tissue.

Use of the fluorescent marker helps surgeons to distinguish the most aggressive cancer cells from other brain tissue and they hope this will ultimately improve patient survival.

The research was presented to the NCRI conference by Dr Kathreena Kurian, a Reader/Associate Professor in brain tumour research at the University of Bristol and consultant neuropathologist at North Bristol NHS Trust, UK. Researchers used a compound called 5-aminolevulinic acid or 5-ALA, which glows pink when a light is shone on it. Previous research shows that, when consumed, 5-ALA accumulates in fast growing cancer cells and this means it can act as a fluorescent marker of high-grade cells.

Professor Watts said: “Neurosurgeons need to be able to distinguish tumour tissue from other brain tissue, especially when the tumour contains fast-growing, high-grade cancer cells. 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.

“The advantage of this technique is that it may highlight more quickly high-grade disease within a tumour during neurosurgery. What this means is that more of the tumour can be removed more safely and with fewer complications, and that’s better for the patient.”

The study involved patients with suspected high-grade gliomas treated at a number of UK centres. They were aged between 23 and 77 years, with an average age of 59 years. Before surgery to remove their brain tumours, each patient was given a drink containing 5-ALA.

Surgeons then used operating microscopes to help them look for fluorescent tissue while removing tumours from the patients’ brains. The tissue they removed was sent to the pathology lab where scientists could confirm the accuracy of the surgeons’ work.

A total of 99 patients received the 5-ALA marker and could be assessed for signs of fluorescence. During their operations, surgeons reported seeing fluorescence in 85 patients and 81 of these were subsequently confirmed by pathologists to have high-grade disease, one was found to have low-grade disease and three could not be assessed.

In the 14 patients where surgeons did not see any fluorescence, only seven tumours could be subsequently evaluated by pathology but in all these cases, low-grade disease was confirmed.

The researchers cautioned that the study looked at patients who were already suspected to have high-grade tumours, and a larger study in which more patients have low-grade disease would provide more information on the use of this technique. They added that other types of markers may need to be tested for detecting low-grade glioma cells.

The next steps could include testing the 5-ALA in children with brain tumours, or to help surgeons distinguish between tumour tissue and scar tissue in adult patients whose brain cancers have recurred following treatment.

Professor Anthony Chalmers is Chair of NCRI’s Clinical and Translational Radiotherapy Research Working Group and Chair of Clinical Oncology at the University of Glasgow, and was not involved in the research. He said: “There is a desperate need for better treatments for brain tumours and to achieve that we need more high quality research in this area. This technique provides on-the-spot information to help surgeons tailor the operation according to the location, size and grade of the tumour. We know that patients who have near total removal of their tumour have better outcomes, so we are optimistic that, in the long term, these new data will help to increase survival times for glioma patients.”