Immune checkpoint inhibitors have emerged as a breakthrough therapy in the treatment in various metastatic cancers. In parallel, the role of radiotherapy in metastatic cancers has been expanding to include stereotactic ablative radiotherapy for oligometastases, in addition to the more conventional palliation of symptoms. Thus, many patients are appropriate candidates for both radiation and immunotherapy-highlighting the need for data to guide this treatment combination in patients with metastatic disease. Here, we review the literature to address questions regarding the safety of combined treatment (focusing on radionecrosis and pneumonitis), and the impact of dose, timing and site of radiotherapy. Finally, we highlight ongoing work investigating the potential local and systemic benefit to combining these therapies.
Keywords: Checkpoint inhibitors; PD-1 inhibitors; immunotherapy; metastatic; radiotherapy.