Alexandre Carpentier of the Pitie-Salpetriere Hospital in Paris said the exploit was "a world-first" in its use of multiple advanced techniques and of local anaesthesia rather than general sedation.
So far, eight volunteers have been treated in the pilot programme, launched December 2006, Carpentier told AFP.
"They were suffering from metastasing brain tumours caused by various cancers, mainly lung and breast cancer that failed to respond to conventional treatment and were otherwise inoperable," he said.
Doctors had given the volunteers only three months left to live, on average.
Under the pioneering technique, a minute hole three millimetres (0.12 of an inch) wide was drilled into the skull, allowing the surgeon to introduce a water-cooled fibre-optic laser into the brain.
The device was gently guided towards the tumour area with the help of a magnetic resonance imaging (MRI) scanner.
Every three seconds, a computer workstation calculated the temperature at the area being burned by the laser to ensure that there was no dangerous overheating and to confirm that only tumorous cells were being destroyed.
The patient received only a local anaesthetic, remaining conscious in order to be able to speak to the medical team to help verify that cerebral functions were not being harmed.
However, "the patients feels nothing during the operation and generally can leave hospital 14 hours later, the evening or the morning after the operation," the surgeon said.
The results are "conclusive," said Carpentier.
Treating the patients completely requires two or more bouts of surgery, and there had been no cases of cerebral bruising or epilepsy.
So far, six of the eight have completed the full programme. Of the six, five have not had a relapse -- a return of cancerous cells to the brain -- at a nine-month monitoring point.
"This is the first time that laser technology has been used intracranially, meaning inside an enclosed skull, using MRI in real time to avoid collateral damage," said Carpentier.
"This is the forerunner of future techniques in which MRI will play a core intervention role in neurosurgery."
The pilot trial, reported in the latest issue of the US journal Neurosurgery, was carried out under the supervision of the French Health Products Safety Agency (Afssaps).
It drew on advanced technology supplied by the M.D. Anderson Cancer Center in Houston, and a Texan company, BioTex Inc., which specialises in the use of lasers for medical therapy.