In a boost to immunotherapy for cancer treatments researchers have found a way to use light to guide the immune system to attack tumour cells. In mice with melanoma on the ears the optical control was sufficient to allow the immune system to nearly wipe out the melanoma with no toxic side effects the study published online in the journal Nature Communications said. The method is similar to sending light on a spy mission to track down cancer cells said lead author Minsoo Kim Professor at University of Rochester Medical Centre in New York. Immunotherapy is different from radiation or