Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of several cancers, significantly increasing survival in advanced disease. A substantial proportion of these patients have received radiotherapy (RT) prior to or after ICI treatment. We have aggressively moved toward strategies combining RT and immunotherapy concurrently or sequentially in oligometastatic disease. Importantly, this strategy has gravitated to earlier stages of disease, with some outstanding successes.1 What have we learned about the toxicity implications associated with this combination, and how might we mitigate harm to the patient?