Light therapy tackles cancer

Beams of light could be the latest weapon for doctors fighting a tough-to-treat cancer which kills nine out of ten patients.
Photodynamic therapy, according to a research paper, increased the expected lifespan of many of the 16 pancreatic cancer patients who underwent it.
There are two stages to the treatment. Firstly, a drug is given which "sensitises" cells to the effects of light.
If these cells are exposed to strong light, they die.
Then, a fibre-optic cable is placed near the target tumour, and light is precisely aimed through it.
When the beam hits the tumour cells, it kills them, hopefully without damaging too many surrounding cells.
The research, carried out at University College London and detailed in the journal Gut, involved patients with inoperable advanced cancer, who were not expected to live long.

Longer lives
Surgery and radiotherapy are difficult in pancreatic cancer, because the gland is tucked away close to vital organs and blood vessels.
Doctors gave the patients a sensitising agent called Foscan, then three days later inserted six needles carrying the laser light fibres into their tumours.
The tumours shrank in all the patients, and although the average prognosis was six to 10 months of life, almost half were alive a year later, two survived for two years, and one managed 30 months.
Side-effects were also far lighter than alternative treatments, with patients eating and drinking within 48 hours and leaving hospital 10 days after treatment.
The authors of the study said they were encouraged by the results.

Exposure to sunlight
The drugs used in the experiment are not without their own risks.
Because they are not particularly "selective", being present in normal as well as tumour cells, there is a danger that too much "collateral damage" can occur to tissue surrounding the tumour.
In addition, patients must avoid skin exposure to bright light for some time after treatment, as this can cause significant damage.
The patients in this study were kept in dimly-lit rooms immediately after treatment, and advised to avoid strong sunlight for some time afterwards.
However, other teams in the UK are working on photosensitising chemicals which are far more selective.
Professor Stanley Brown, director of the Leeds Centre for Photobiology and Photodynamic Therapy, told BBC News Online: "Photodynamic therapy allows a targeted approach - it can be far less traumatic than surgery.
"I think in the future it will be used far more to treat early cancer and pre-cancerous conditions, as better screening picks them up."
Similar treatments are being developed to tackle wound infections.