The aim of this study was to discern an abscopal effect by modifying the delivery of radiation for metastatic malignant melanoma. The effect would be directly evident with visible/radiographic regression of the disease and indirectly shown with an overall extension in survival and potential cure. Patients with locally advanced, metastatic palpable, or radiographic visible metastatic malignant melanoma were treated with twice-daily radiation therapy using a dose range of 100-135 centigray (cGy) per fraction. A 100% complete response/continued regression with no recurrence was achieved within the region of delivery for every patient so treated. Of those alive at three years, few demonstrate a progression of the disease. These results were achieved without the use of immunotherapy, created few side effects, and were accomplished at a fraction of the alternative's cost. Evidence of an immune-mediated response (abscopal effect) was commonly seen. Treatment was administered within acceptable dose ranges, historically used twice daily for other malignancies known to be sensitive to the effects of radiation.
Keywords: abscopal effect; hyperfractionation; malignant melanoma; metastatic malignant melanoma; radiation therapy; twice-daily radiation.