British scientists have invented what they are calling "the lamp that thinks it's a laser", a device the size of a household toaster that kills cancer cells using photodynamic therapy like a laser, but at one-twentieth the cost, The 1 amp treatment has already been successfully used to treat more than 150 cases of skin cancer and there are now plans to try it against breast, prostate and bowel cancers. Meanwhile there are plans to manufacture the lamp on a large scale so the potential benefits of photodynamic therapy can be made available to millions of people around the world.

Photodynamic therapy ( PDT ) is not a new idea. But it has taken five years' work by Dr. Colin Whitehurst of the Paterson Cancer Research Institute in Manchester to find a way to make PDT widely available. Dr. Whitehurst says: "This lamp treatment is part of a two pronged attack on cancer. A light-sensitive cream or paste is applied to the cancer and is absorbed by it. Then a light source producing light of special qualities, my lamp, is used to irradiate the cancer that has been coated with the cream. And within a few weeks the cancer has gone."

Two or three different chemicals have been discovered that are readily absorbed by living cells and are harmless until intense light is shone on them. Then they break down and release deadly cell-killing poisons such as free oxygen radicals which are so reactive that they react with, and break down, vital structures in the cells, tearing them to pieces and destroying the cells. Among the photoactivated chemicals are those which are to some extent selectively absorbed by cancer cells. Research has focused on finding ways to deliver these chemicals selectively to cancer cells and to concentrate light upon them so as to kill the cancer cells without damaging normal cells.

Big Future
Recent successes have encouraged doctors to believe that PDT could have a big future in cancer therapy. But the relatively high cost of the lasers that have been needed to deliver intense light at the right wave length has held back development of the treatment. The lamp invented by Colin Whitehurst can make treatment much cheaper. The Paterson Lamp, no bigger than a household toaster, produces intense light at the right wavelength from an electric, a current jumping across a gap. The light focused by lenses and directed by flexible fibre optics to the cancer awaiting treatment.

Colin Whitehurst explains: "The light, which has to be tuned to a specific wavelength, which is critical, kills the cancer cells but does not harm the normal cells surrounding them. This allows the body to regenerate healthy tissue to fill the gap that was once occupied by the turnour. So at the end of the treatment there's no scarring, no ulceration, you'd never know the cancer had been there in the first place."

So far the lamp has been used in PDT in hospitals in Leeds and Glasgow to treat more than 150 patients, including some affected by the scarring skin disease called Bowens disease as well as two of the most common forms of skin cancer. Like laser-based PDT, it is not effective against melanoma, the most deadly form of skin cancer.

"Results from those first two or three trials (says Dr. Whitehurst) have been very promising, the doctors are well pleased with the results and the ease of operation . After one treatment, twelve months later more than 90% of had been eliminated. And because, unlike conventional cancer chemotherapy, the cancers do not build up resistance to the treatment, tumours that were not killed can be treated with the same effectiveness as with the first treatment. So there is no excuse for failing to destroy these cancers."

Undeniably Exciting
These results are undeniably exciting. Colin Whitehurst says doctors at Glasgow's Western Infirmary where the treatment was first tested are now planning to widen the scope for it.

"We are planning further trials against breast, ovarian, gullet and bowel cancers and against some non-cancer diseases such as the skin disease psoriasis. That is in the pipeline now. The use of PDT has been held back by the cost of the lasers required, around £l00,000 a piece plus expensive servicing. My light source costs about one-twentieth of that, and should allow a lot more people to benefit."

The lamp has been patented and medical equipment companies are now negotiating to manufacture on a large scale for use in hospitals worldwide. Dr. Gordon McVie, director-general of the UK Cancer Research Campaign who supported the development of the Paterson Lamp, says the lamp should be in production by the end of the year.

For more information contact:
Professor Gordon McVie, Director General
Cancer Research Council
10 Carnbridge Terrace
London, United Kingdom, NW 1 4JL
Tel: +44 171 224 1333
Fax: +44 171 487 4310