AN electron beam gun is being used to attack brain tumours in trials at a London hospital after encouraging tests of a prototype in America.
The miniature gun fires electrons along a diamond-coated needle to the heart of any solid tumour.
The battery-powered device accelerates the electrons to the needle tip, where they collide with a gold target to create a splash of X-rays that are mostly absorbed by the cancer rather than healthy tissue.
By using electromagnetic fields to steer the way the electrons hit the gold target, doctors can shape the profile of the X-rays delivered to the tumour in a treatment that takes about 30 minutes.
"The more localised you can make the treatment, the better," said Dr Euan Thomson, of
Norfolk and Norwich Health Care NHS Trust, who is involved in the trials.
"This is advanced technology which has provided a way to produce X-ray radiotherapy from the inside of a tumour which has never been done before." Although not commercially available, it has completed initial trials at the Massachusetts General Hospital in Boston.
Fourteen patients with cancers that had spread to the brain were treated without complications.
The gun, which is 3mm wide, can be inserted in the same track used to take a biopsy of a brain tumour, reducing damage to healthy tissue. In almost all the cases, these metastatic tumours of the brain, consisting of melanoma, renal and lung tissue, stopped growing.
Further studies of the device have begun at cancer hospitals. The first patient has been treated at the Royal Free Hospital, London, and other trials are under way in Japan, Australia and the United States.
Doctors have high hopes of the efficacy of the prototype device, which also offers patients suffering from metastatic brain tumours a cheaper alternative to traditional methods.
The equipment used to calibrate and run the gun will cost around £330,000, up to 10 times less than existing systems, such as linear accelerators and "gamma knives" that deliver radiation through the skull and affect intervening skin and tissue.
"Our goal is to make life easier for patients by alleviating their suffering and cutting the cost of treatments," said a spokesman for the Photoelectron Corporation, which developed the device in Waltham, Massachusetts.
"We expect the system to become an important weapon in the arsenal against cancer."
Tests are now starting, using a longer probe, to treat bladder cancer. Within the next year, the team expects to announce trials on solid tumours in the liver, kidneys and breast.
