Light therapy ‘targets cancer spread’

A light-triggered treatment could target cancer’s spread on two fronts, according to a new study.

Known as photodynamic therapy (PDT), the treatment is a relatively new technique which uses drugs that are usually harmless but become highly effective at killing cancer cells when exposed to light.

Research published in the British Journal of Cancer argues that PDT could target local tumours at the same time as treating advanced cancer.

When a light is shone on a tumour after one of these drugs has been injected it selectively activates the drug in that area.

Commenting on tests which involved tumours in the shoulder and lungs, lead researcher Dr Sandra Gollnick said: “Solely treating the tumours in the shoulder worked as normal for PDT. But it also sparked off an immune response that reduced the number of tumours in the lungs as well.

“We made sure this wasn’t due to activated drug reaching the lung tumours, and we were able to identify the precise part of the immune system being activated.”

Although this response has been predicted before it is the first time that the effect has been seen in such detail.

Dr Lesley Walker, director of cancer information at Cancer Research UK, said: “A lot more research is required before we will know the full potential of PDT. This type of lab work is interesting, however, because it raises the prospect of a future treatment that could be applied locally but then stimulate the body’s own defences to seek out and destroy similar cancer cells elsewhere in the system.”