Could LEDs help treat skin cancer?

It sounds counterintuitive--that light, so often considered the culprit in skin cancer, might also play a role in its treatment. But researchers at the University of California at Irvine are using light-emitting diodes to improve a cancer therapy that they hope to use to treat skin cancer.

The technique is called photodynamic therapy (PDT), and is approved by the Food and Drug Administration to treat both esophageal and lung cancer. Light-absorbing chemicals are injected into tumors and then exposed to light, which prompts the chemicals to generate oxygen radicals that destroy cancer cells.

The technique has the potential to treat the most common type of nonmelanoma skin cancer, called basal cell carcinoma, but the therapy currently lacks detailed imaging with which physicians can target and monitor the therapy's effect.

So a team at UC Irvine, along with Modulated Imaging, has designed a new device with a five-color array of LEDs that illuminates skin with distinct intensity patterns that change depending on tissue structure and pigment type. The resulting images should reveal the tissue's biochemistry, and therefore the nature of the affected tissue.

To test this system, called spatial frequency domain imaging, the team imaged skin cancers pre-treatment to identify specific characteristics of each subject and lesion. It took 5 to 10 seconds to produce images with a resolution of 30 microns that reveal tissue oxygenation and the drug's distribution.

Their next step is to monitor the tissue during PDT treatment regimens.

"Through this imaging modality, it is now possible to assess how the therapeutic light will travel throughout the affected tissue, quantify the drug present within the lesion and monitor its efficacy during treatment," says Rolf Saager, a researcher at the Beckman Laser Institute at UC Irvine.

The team is presenting a talk on their work at the Optical Society's 94th annual meeting, Frontiers in Optics 2010, in Rochester, N.Y., on October 26.