Scorpion-based 'tumour paint' may help brain surgeons identify cancer cells

In collaboration with the Press Association

Researchers have developed a 'tumour paint' which, when injected, could make it easier for surgeons to tell the difference between cancerous and healthy tissue.

Surgeons currently have only limited ways of differentiating between tumour cells and healthy cells, making it hard for them to remove all of the cancerous cells without damaging surrounding tissue.

However, researchers at Seattle Children's Hospital Research Institute and Fred Hutchinson Cancer Research Centre have developed a substance called chlorotoxin:Cy5.5, which is based on a molecule found in scorpion venom.

When injected, chlorotoxin:Cy5.5 binds to cancer cells within minutes and emits a near-infrared light, causing the cancer cells to emit visible light when illuminated with infrared light.

According to the study in the journal Cancer Research, it enables tumours with as few as 2,000 cancer cells to be identified, making it 500 times more sensitive than magnetic resonance imaging (MRI), the most sensitive method currently used to detect tumours.

Senior author Dr James Olson, a researcher at Seattle Children's Hospital and the Hutchinson Centre, commented: "By allowing surgeons to see cancer that would be undetectable by other means, we can give our patients better outcomes."

The technique could prove particularly useful in the treatment of brain tumours, where around 80 per cent of cancers have been shown to recur at the edges of the area previously operated on.

The researchers found that they could illuminate brain tumours as small as one millimetre in diameter in mice without any of the surrounding tissue being lit up.

Co-investigator Dr Richard Ellenbogen, a paediatric neurosurgeon at Seattle Children's Hospital, said: "This development has the potential to save lives and make brain tumour resection safer."

Professor John Griffiths, head of molecular imaging at Cancer Research UK's Cambridge Research Institute, said: "The big problem with surgery for brain cancer is that tumours can infiltrate normal brain tissue, making it very hard to tell where the tumour ends and the normal tissue begins.

"If you could light up the tumour cells by shining an infrared beam on them, it might be very helpful."

The researchers suggest that the technique could be used on human patients within 18 months, but Professor Griffiths pointed out that the technique has so far only been tested in mice.

"The researchers haven't shown why the 'paint' is specific to brain cancer in mice. They will need to show that it would also work in humans, and they also have to ensure it is not toxic at the necessary doses," he commented.

"The most common - and most malignant - form of brain cancer is glioblastoma multiforme, which is notoriously difficult to treat. The only new treatment in recent years has been temozolomide, developed from Cancer Research UK-funded science, which extends lives by several months.

"But a way to improve surgery for brain cancer would be extremely welcome," he added.