External beam radiotherapy is a safe and effective curative treatment modality for men with localized prostate cancer (PCa). While traditionally entailing long courses with low daily doses, an appreciation of prostate radiobiology and advancements in radiation delivery have allowed for more abbreviated courses of EBRT. Ultrahypofractionated radiotherapy, which involves the delivery of >5 Gy/fraction, is now considered a standard of care regimen for localized PCa, especially intermediate-risk disease. Stereotactic body radiotherapy (SBRT), a specific form of ultrahypofractionated radiotherapy that utilizes advanced planning, imaging, and treatment technology to deliver in ≤5 fractions, is in particular emerging as a cost-effective, convenient, and safe alternative to longer courses of radiotherapy. Given SBRT's recent adoption into the standard-of-care armamentarium of PCa treatment and its increasing utilization in this setting, it is important to highlight practical considerations pertaining to patient selection, fractionation scheme, target delineation and planning objectives, particularly when practitioners are faced with difficult clinical situations without clear evidence to provide guidance. The objective of this case-based guide endorsed by the Radiosurgery Society is to provide a practical framework for delivering SBRT to the intact prostate, especially in areas of controversy, illustrated by two challenging cases. In this article, we will discuss common SBRT dose/fractionation schemes and dose constraints for organs-at-risk. We will also review existing evidence and expert opinions on topics such as SBRT dose escalation, utility of rectal spacers, the role of androgen deprivation therapy in the setting of SBRT, SBRT in special patient populations such as those with high-risk disease, large prostate, high baseline urinary symptom burdens and inflammatory bowel disease, as well as new imaging-guidance techniques (e.g. Magnetic Resonance Imaging) for SBRT delivery.
Practical radiation oncology. 2023 Sep 01 [Epub ahead of print]
Ting Martin Ma, Colton Ladbury, Maxwell Tran, Timothy D Keiper, Therese Andraos, Emile Gogineni, Najeeb Mohideen, Shankar Siva, Andrew Loblaw, Alison C Tree, Patrick Cheung, John Kresl, Sean Collins, Minsong Cao, Amar U Kishan
Department of Radiation Oncology, University of Washington, Seattle, WA, USA., Department of Radiation Oncology, City of Hope National Cancer Center, Duarte, CA, USA., Department of Radiation Oncology, Medical University of South Carolina, Charleston, SC, USA., Department of Radiation Medicine and Applied Sciences, University of California San Diego, San Diego, CA, USA., Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, OH, USA., Department of Radiation Oncology, Northwest Community Hospital, Arlington Heights, IL, USA., Peter MacCallum Cancer Centre and Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria, Australia., Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Science Centre, University of Toronto, Toronto, ON, Canada., The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, London, UK., Phoenix CyberKnife and Radiation Oncology Center, Phoenix, AZ, USA., Department of Radiation Medicine, MedStar Georgetown University Hospital, Washington, D.C., USA., Department of Radiation Oncology, University of California Los Angeles, Los Angeles, CA, USA., Department of Radiation Oncology, University of California Los Angeles, Los Angeles, CA, USA; Department of Urology, University of California Los Angeles, Los Angeles, CA, USA. Electronic address: .