Brain metastases, Immunotherapy, Lesion response, Melanoma, SRS, Adult, Aged, Aged, 80 and over, Brain Neoplasms, Cell Cycle Checkpoints, Combined Modality Therapy, Databases, Factual, Humans, Immunotherapy, Kaplan-Meier Estimate, Melanoma, Middle Aged, Multivariate Analysis, Proportional Hazards Models, Prospective Studies, Radiosurgery, Time Factors, Treatment Outcome