Radiation Necrosis Following the Radiosurgical Treatment of Brain Metastases

Abstract

Stereotactic radiosurgery is becoming increasingly utilized in the management of metastatic intracranial tumors. As treatment advances for systemic cancers extends life expectancy and, as a result, increases the prevalence of these lesions, radiosurgery has become an invaluable and effective treatment modality. However, with a greater reliance on radiation-based methods of treatment, the incidence of radiation-induced side effects, specifically radiation necrosis, is also increasing. As a disease entity in its own right, one of the most challenging aspects of radiation necrosis lies in its diagnosis. Many characteristics of radiation necrosis are similar to tumor progression, including its symptomatology and appearance on the most commonly used imaging modalities. Current research is working to uncover the underlying pathophysiology of radiation necrosis. Recent studies are suggesting significant immune system involvement in the development and progression of radiation-induced changes in the brain tissue surrounding these treated lesions. Therefore, as a likely immunologically driven phenomenon, the concurrent use of immunotherapies with radiosurgery to treat metastatic brain lesion needs to be further evaluated and understood in the setting of radiation necrosis. A better understanding of its underlying biology and pathophysiology is needed to treat, and preferably prevent, radiation necrosis and maximize the effectiveness of stereotactic radiosurgery in the treatment of metastatic brain lesions.