A rarely seen phenomenon in cancer patients -- in which focused radiation at the site of one tumor is associated with the disappearance of metastatic tumors all over the body -- has been reported in a patient with melanoma treated with the immunotherapeutic agent ipilimumab (Yervoy™). Researchers at Memorial Sloan Kettering Cancer Center shared their findings in a unique single-patient study, which could help shed light on the immune system's role in fighting cancer. Their observations suggest that the combination of ipilimumab and radiation may be a promising approach for the treatment of melanoma. The findings are published as a brief report in the March 8 issue of the New England Journal of Medicine. The phenomenon reported by the researchers, known as the abscopal effect, occurs when localized radiation therapy delivered to a single tumor in a patient with advanced disease results in tumor disappearance outside of the irradiated area. Though the abscopal effect is extremely rare, it has been described in several cancers including melanoma, lymphoma and kidney cancer.