Why turning tumours pink is a bright idea
23:47 GMT, 26 November 2012
Turning tumours pink may help surgeons cut out the cancer without damaging surrounding healthy tissue
Making cancerous tumours glow bright pink in the dark is the latest technique for improving the success of surgery.
The idea is that this will help surgeons cut out the cancer without damaging the surrounding healthy tissue.
Medics are testing the technique in a new trial on 60 brain tumour patients, but hope it can be used to tackle other types of cancer, such as breast, bowel and ovarian.
Brain tumours are responsible for most cancer deaths in the under-40s — 8,500 people are diagnosed with a primary brain tumour each year.
Dr Colin Watts, consultant neurosurgeon at the University of Cambridge, who is leading this trial, says: ‘The number of patients diagnosed with brain tumours is actually rising. We’re not sure why this is, but factors may include better scanning and greater access to MRI, and also an ageing population.
‘However, survival rates remain one of the worst of all cancers.’
He stresses that precision is even more crucial when removing a brain tumour: ‘In certain areas of the brain, such as those controlling movement, a millimetre can make the difference between a patient being disabled, or being able to walk out of hospital.’
In the new trial, patients are being given around 50ml of a colourless, bitter drink five hours before surgery. This contains a naturally occurring type of amino acid (a compound in the body that helps builds protein), called 5-ALA.
For reasons that are not clear, this compound is converted into high amounts of fluorescent protein by cancerous cells (healthy cells produce much less of the fluorescent protein).
When an ultraviolet light is shone on them during surgery, these tumours shine pink, which can be seen with the naked eye.
This enables surgeons to see the edges of the irregular-shaped tumour more clearly, and remove it accurately. Early-stage studies suggest that surgeons can spot a tumour 30 times smaller than could be detected using traditional techniques — on average, they found 34 tumours using this technique, compared with an average of seven using standard methods.
Once the tumour is removed, the surgeon places up to eight ‘wafers’ of a chemotherapy drug into the cavity that remains. These resemble tiny tiddly-winks and are 7mm in diameter and 0.5mm thick. The wafers deliver high concentrations of chemotherapy to surrounding tissue over the next four to six weeks, killing any rogue cancer cells left behind.
Better scanning and greater access to MRI may be factors as to why the number of patients diagnosed with brain tumours is rising, according to one neurosurgeon
The patients in the trial, which is
jointly funded by The Brain Tumour Charity and Cancer Research UK, will
have been newly diagnosed with glioblastoma, which is the most common
and most harmful brain tumour in adults — patients survive an average of
just 15 months after diagnosis.
The technique is being rolled out to
other centres, including Liverpool, Glasgow, King’s College Hospital and
the National Hospital For Neurology And Neurosurgery in London.
Researchers in Leeds are setting up a similar trial working with bowel
cancer patients, and the technique is being used in a trial on breast
cancer patients in Germany, and in ovarian cancer patients in the
Commenting on the study, Peter Dickens, from the charity Brain Tumour UK, said: ‘The start of this trial is excellent news for brain tumour patients.
‘Unfortunately, patients diagnosed with this type of tumour have few treatment options available to them. The data from this trial will hopefully provide surgeons and oncologists with the information they need to improve survival — and provide hope to people affected by this devastating disease.’
Professor John Kelly, oncologist at University College London Hospitals, added: ‘The whole surgical community will look forward to the results with interest because, if it works, the benefits will be enormous.’
Meanwhile, scientists say that fluorescent molecules can be used to monitor the temperature inside cells of the body, and allow doctors to differentiate between cancerous and non-cancerous cells.
In the lab-based study, the researchers used a special type of green fluorescent protein that is absorbed by cells in the body.
Once in the cells, they act as an accurate temperature gauge, and glow brighter in hotter temperatures.
Cancer cells divide and grow at a rapid rate, which is why they can spread so quickly throughout the body.
However, the team behind the new research, from the Institute Of Photonic Sciences in Spain, say they can use this to their advantage. Cells that are growing and dividing generate more heat, and so will be more fluorescent.
The team hope this method will enable scientists to clearly distinguish between cancerous and healthy cells, and also allow them to gauge how aggressive a cancer is, as the ‘hottest’ (and hence brighter) cells will be growing at a faster rate.