The average life expectancy for a brain cancer patient after standard surgery is 51 weeks. Using the new technique, doctors have extended this to 91 weeks.

Dr Robert Salker, a neurosurgeon at the Western Pennsylvania Hospital, has been testing the technique.

He said: "This method has proven to be of value in increasing life expectancy. A cure is elusive. But we are attempting to expand the quality of life period."

Traditional treatment involves radiation therapy

The traditional treatment for brain tumours is surgery followed by doses of radiation.

The new technique also has two stages. First, the patient is injected with a light-sensitive drug called Photofrin.

The drug disappears from normal tissue after 30 hours, but remains in tumour tissue.

In the second phase, a laser that kills tumour cells is trained on the cancerous cells. The tumour can then be surgically removed.

The hospital is one of five medical centres in the US and Canada using the treatment in a clinical trial that is being funded by the US National Institutes of Health.

About a dozen patients have been treated so far, two of them at Western Pennsylvania Hospital.

Dr Selker said there are 13,000 new cases of brain cancer diagnosed every year in the United States.

"Our hope is that this (method) is going to help us increase the quality of life for patients," he said.

Other uses

There are no major side-effects from the treatment, but Dr Selker said patients are temporarily photosensitive and must take precautions to avoid direct sunlight and bright indoor lights for 30 days.

The procedure has been used at other medical centres to treat tumours in less sensitive parts of the body such as the lungs and oesophagus.

In the UK, research is being carried out on a similar technique, known as Boron neutron capture therapy. Patients are given a non-toxic compound that accumulates in the brain.

A beam of low energy neutrons is then fired at the affected area where they react with the compound to produce localised, cancer-killing nuclear particles.

The research is focusing on malignant gliomas, the most common cancer of the brain, which affects more than 3,500 adults and 250 children in the UK each year.