Focusing sunlight on to tumours replaces costly lasers

Using little more than a parabolic mirror, a length of fibre-optic cable and a steady pair of hands, scientists have for the first time harnessed the sun's energy to kill cancer cells.

In much the same way that cancer specialists currently rely on lasers to destroy certain tumours, sunshine surgery has been shown to destroy living tissue with pinpoint accuracy.

The scientists estimate that the equipment needed for performing surgery by sunlight would be hundreds of times cheaper than a comparable laser device for cancer treatment - a great benefit for developing countries where money is in short supply but sunshine is plentiful.

Jeffrey Gordon and his colleagues at Israel's Ben-Gurion University of the Negev in Sede Boger said that using concentrated sunlight focused by a parabolic mirror into a fibre-optic cable could cost between $100 and $1,000 (£70-£700) compared with the $100,000 needed to buy a comparable medical laser. "Even though the deployment of solar radiation for surgery must be restricted to clear-sky periods in sun-belt climates, its appeal lies in its potentially low cost compared with conventional laser fibre-optic treatments," the researchers write in the journal Nature.

Professor Gordon said that the "solar concentrator" has been used to destroy small sections of liver tissue in anaesthetised rats which have survived the surgery without any apparent ill effects. "The purpose was to kill tissue very rapidly and in a localised fashion, thereby avoiding damage to surrounding tissues," Professor Gordon said.

"It's embarrassingly simple. We take a parabolic mirror about 20cm [7.8 ins] in diameter and use it to focus sunlight on to a flat mirror using a simple optical trick," he said. A tracking device ensured that the mirror followed the movement of the sun and an optical fibre carried the focused sunlight into the laboratory.

Conventional laser treatment has been carried out for more than a decade and relies on harnessing the energy of a laser to kill cancerous tissue in situ by applying the light beam using a needle inserted into the organ in question.

Stephen Bown, professor of laser medicine and surgery at the National Medical Laser Centre at University College London, said that in principle there appeared to be nothing to prevent the use of sunlight rather than laser light.

"It's ingenious and highly appropriate for sunny countries without lasers. I can seen nothing wrong with the idea provided I could measure the power coming out of the optical fibre," Professor Bown said.

Professor Gordon said that the next stage was to try to eliminate tumours in laboratory rats and then to move on to experiments with larger animals before attempting clinical trials on humans. "It's certainly possible to begin clinical trials within five year, or less if we receive the funding," Professor Gordon said.