Background
non-skin cancer, death, tumor, toxicity, cancer, toxicities, prostate, GI toxicity, Prostate cancer, lung/bronchus cancer
ADVERSE EVENT, TUMOR, SIDE EFFECT, CANCER, SOLID TUMORS, PROSTATE, PROSTATE CANCER
Prostate cancer (PCa) is the most diagnosed non-skin cancer among men and is the second leading cause of death from cancer in men behind lung/bronchus cancer [Stereotactic body radiation therapy (SBRT) is an ultra-hypofractionated EBRT treatment delivering between 36.25-45 Gy over 5 fractions, and it is increasingly used for certain PCa patients [PACE-B, a randomized phase III trial, compared conventionally fractionated (78 Gy in 39 fractions) or moderately hypofractionated (62 Gy in 20 fractions) IMRT-based regimens to SBRT (36.25 Gy in 5 fractions) for low and favorable intermediate-risk PCa patients. Results from the study showed no significant differences in patient-reported outcomes for acute toxicities. Only physician-reported Common Terminology Criteria for Adverse Events (CTCAE) grade ≥ 2 severe GI toxicity was significantly worse in the SBRT group, however this difference resolved by week 12 following radiotherapy [In addition to the safe side effect profile, practical advantages, and patient-centric convenience of ultra-hypofractionated radiation treatment regimens, there is also biological rationale to provide definitive treatment in 5 or potentially fewer fractions. Among solid tumors, PCa appears unique in that ultra-hypofractionated SBRT-like regimens are hypothesized to expand the therapeutic window between tumor control and late toxicity (due to a purported low α/β ratio) [With technological advances that improve the visualization of targets and precision of radiation delivery during treatment, higher doses can be delivered in fewer fractions with less side effects. The integration of magnetic resonance (MR)-imaging with linear accelerator (LINAC) technology — available with MR-LINAC — allows for better visualization of the prostate and reduces planning treatment volumes, while also enabling real-time tracking of targets and organs-at-risk (OAR) throughout the course of radiation delivery [The theoretical of advantages of MR-guided radiotherapy (MRgRT) are being evaluated on clinical trials including the phase III MIRAGE trial which is comparing standard CT-guided SBRT and MR-guided SBRT for PCa. Interim results from the trial showed that acute grade ≥ 2 GU and GI toxicities were significantly reduced in men receiving MR-guided treatment (24.4% vs. 43.4%, Thus, the FORT trial (NCT04984343) is designed to evaluate whether MR-LINAC SBRT delivered in 2 fractions has a non-inferior GU and GI toxicity profile as compared with MR-LINAC SBRT delivered in 5 fractions among patients with low to intermediate-risk PCa.