Terence Williams, MD, PhD, Editor

Radiation Oncology is a cornerstone of cancer therapy, partnering with Surgery and Medical/Hematology Oncology to enhance outcomes for patients with cancer. In the past few decades, advances in technology have largely driven the administration of more personalized radiation therapy (RT). The advent of intensity-modulated radiation therapy (IMRT), stereotactic body radiotherapy (SBRT/stereotactic ablative radiotherapy [SABR]), and stereotactic radiosurgery (SRS) allowed radiation oncologists to better “carve” radiation dose around critical normal structures, allowing sparing of normal tissues and/or opening up opportunities for radiation dose intensification. In the coming decades, the future of Radiation Oncology remains bright with continued advances in intraoperative radiation (IORT), brachytherapy, particle therapy (protons, carbon), magnetic resonance–guided radiotherapy (MRgRT), PET-guided radiotherapy using biology-guided radiotherapy (BgRT), and radioimmunomodulation (using radiation to harness the immune system). In this Special Issue, we convey the state-of-the-art with leading Radiation Oncology experts in gastrointestinal (GI), hematologic, thoracic, breast, central nervous system, head and neck malignancies, and advanced technologies.