Discussion
toxicity
MALIGNANT DISEASE
Historically, radiotherapy for PCa has consisted of smaller doses of radiation being delivered over longer courses of treatment to minimize toxicity to adjacent internal organs, such as the bladder, bowel and rectum, while delivering a biologically effective dose to treat malignant disease. With innovations in radiation treatment planning and delivery along with evidence supporting low α/β ratio of PCa, it has become possible to deliver higher doses of radiation in fewer fractions without sacrificing patient safety and clinical efficacy. This shift toward hypofractionation and even ultra-hypofractionation with SBRT is of great benefit to patients and health care systems, as it enables them to make fewer trips to their treatment center sparing added financial toxicity and resource utilization associated with more protracted courses. The advent of MR-based planning and radiation delivery is one such technological advancement that allows for hypofractionated and ultra-hypofractionated radiotherapy regimens with favorable OAR sparing. Specifically, MR-guided radiotherapy enhances visualization of and localization to the target volumes while also allowing online adaptive planning and monitoring of the patient's physiologic motion in real-time. Taken together, ultra-hypofractionation and MR-guidance have the capacity to greatly improve patients’ quality of life both during and after their treatment. The FORT trial is one of few trials currently evaluating whether MR-guidance can effectively minimize toxicity amidst an ultra-hypofractionated radiation treatment regimen for definitive management of localized PCa. We hope that the data from this trial elucidates the non-inferiority of 2 vs. 5 ultra-hypofractionated MR-guided radiotherapy allowing for new therapeutic options for men with low or intermediate risk PCa.