By David Derbyshire
Last updated at 1:46 AM on 30th June 2009
A revolutionary treatment for breast cancer which destroys tumours with a blast of laser light was unveiled by doctors today.
The technique involves no surgery, can be carried out in only a few minutes and does not harm healthy cells.
A team of British surgeons plans to start clinical trials of 'photodynamic therapy' on 20 patients this year.
A woman receiving photodynamic therapy, which can be used to treat various cancers, including skin and breast
It is the first time worldwide that doctors will test the technique on primary breast cancer. Previously, it has been used on cancers of the skin and mouth.
The procedure is being pioneered by Mo Keshtgar, a world-renowned breast cancer surgeon, at the Royal Free Hospital in North London.
During photodynamic therapy, or PDT, a drug is injected into the patient's bloodstream which makes the cancer cells extremely sensitive to light.
Photodynamic therapy uses tumour-killing drugs that are activated by light
When a low-level laser beam is shone at the cancer through the skin, the cells self-destruct. Researchers, who announced their plans to start trials at the Royal Society's Summer Science Exhibition, said it could even offer an alternative to radiotherapy for some women.
'The key appeal is that it attacks and destroys cancer cells while retaining the viability of the surrounding normal cells,' said Mr Keshtgar.
A patient undergoing a mammogram to see if she has breast cancer
'Breast cancer can be particularly traumatic, with more invasive treatments leaving physical and emotional scars.
'Our treatment will keep the structure of the connective tissue intact, meaning the breast does not become deformed or lose shape.'
The drug - called a photosensitising agent - is injected directly into patients and finds its way into the breast's epithelial cells, lining cells which can become cancerous. The drug makes these cells highly sensitive to light.
Because tumours have high metabolic activity and are surrounded by a proliferation of new blood vessels, the drug accumulates in cancer cells in preference to healthy cells.
Once the drug has been taken up by the cancer cells, surgeons point a low-powered red laser at the tumour.
The light triggers a chemical reaction which kills the harmful cells. The drug loses its potency after a few hours.
However, patients are kept in a subdued
light for 24 hours after their treatment and then told to avoid bright sunlight for another 24 hours.
Mr Keshtgar said the technique could be available within six years, once it has been properly tested on volunteers.
The initial small-scale trial will be on breast cancer patients due to have mastectomies. They will have PDT just before their surgery, after which the tissue will be examined to determine the effects.
If the trials are promising, the team will recruit women to take part in a larger trial. They will be monitored for five years after their treatment.
Traditional treatment: Chemotherapy
Mr Keshtgar said the technique could help patients anxious about surgery or who are not well enough for invasive operations.
Dr Alexis Willett, head of policy at Breakthrough Breast Cancer, said: 'We welcome research into new therapies that may reduce the need for invasive treatment.
'It will be interesting to see how trials progress.'
PDT trials are already underway for cancers of the prostate, bile duct and pancreas.
Around 46,000 women are diagnosed with breast cancer each year in the UK. It is the most commonly diagnosed cancer and accounts for nearly a third of cancers in women.
One in nine women will develop the disease at some point in their lives, while more than 1,000 die of it each month.