Fractionated radiotherapy is crucial for effective multimodality, multidisciplinary management of patients with brain metastasis as well as most primary brain tumors. For patients with newly diagnosed brain metastasis, the recognition of the importance of cognitive function has led to the development of pharmacologic approaches to mitigate the side effects of whole-brain radiotherapy as well as promulgated the development of advanced hippocampal avoidance techniques. For patients with gliomas, up-front radiotherapy along with concurrent chemotherapy is now recognized to be associated with long-term survival for those with lower World Health Organization (WHO) grade or favorable molecular features and remains the standard backbone of treatment for those with higher grade disease as new chemotherapeutics are being tested. For patients with meningiomas, the role of radiotherapy currently depends upon patient factors (i.e., medical operability, surgical resectability, location), disease factors (initial versus recurrent disease), and molecular features (i.e., WHO grade, Ki-67). For patients with rarer tumor subtypes, such as vestibular schwannoma and pituitary adenomas, advances in radiotherapy delivery techniques and the introduction of particle beam radiotherapy help to maintain the favorable tumor control rates associated with radiotherapy but reduce the long-term toxicities associated with treatment. Finally, experience with particle beam radiotherapy has led to striking advances in patients with aggressive chordomas or chondrosarcomas. As we enter an era of modern radiotherapy, with significant advances in patient selection and prognostication, tumor evaluation and risk stratification via key molecular profiling, and impressive radiotherapy research and technological development, our efforts are underscored by the principle tenet behind fractionated radiotherapy: to widen the therapeutic ratio of our treatment. Fractionated radiotherapy and single-fraction radiosurgery are now at a crossroads with amalgamation of concepts and use of either or both approaches in patients selected based on desired outcomes. Radiosurgery concepts and outcomes are discussed in a separate chapter.
