ABSTRACT
Brain metastases (BrM) are a significant cause of morbidity and mortality, occurring in approximately 10% to 30% of cancer patients at one point in the course of their disease. In this chapter, the authors review the literature on the interplay between immunotherapy and stereotactic radiosurgery (SRS) for brain and spine metastases. In recent years, numerous investigators have explored the combination of immunotherapy and SRS in the management of patients with BrM in an effort to improve rates of local and distant intracranial control. When compared to traditional chemotherapeutic agents, immunotherapy drugs have a unique complement of adverse effects (AEs). Key to their mechanism of action, these agents upregulate the immune system, causing inflammatory AEs. Pseudoprogression, a phenomenon occasionally observed in tumors treated with immunotherapy, occurs when there is initial apparent tumor growth, followed by tumor regression. Pseudoprogression can be distinguished from true disease progression through biopsy or serial imaging.
