MR-guided adaptive radiotherapy (ART) enables daily plan optimization for prostate cancer but is resource-intensive. This study evaluated dosimetric and clinical outcomes following transition from radiation oncologist (RO)-led to radiation therapist (RTT)-led MR-guided ART. All prostate cancer patients treated with MR-guided ART on a 1.5T MR-linac were retrospectively reviewed. Consecutive RO-led (September 2019-November 2021) and RTT-led (April 2022-October 2023) cohorts were compared, excluding the actual transition period. Toxicities (CTCAE v5.0), dose-volume metrics from daily adapted plans, target volume variation, and biochemical recurrence-free survival (BRFS) were analyzed. A total of 166 patients were included (78 RO-led, 88 RTT-led; median follow-up 40 and 35 months). Dosimetric differences between the cohorts were statistically small (<1%). Rates of G2+ GI adverse events were similar across all timepoints. An increase in on-treatment GU events was observed in the RTT-led cohort (G2+ 27% vs. 9%, G3 incidence n = 2 vs. n = 0), likely reflecting higher baseline urinary dysfunction; no post-treatment differences persisted. Early biochemical outcomes were comparable, with 36-month BRFS of 93.5% (RO-led) and 95.0% (RTT-led). RTT-led MR-guided ART achieved comparable dosimetric quality and early biochemical outcomes to RO-led workflows with adverse advents that resolved in the long term. With structured training and a mature practice setting, RTT-led ART represents a scalable model to support future adaptive radiotherapy practice.
Current oncology (Toronto, Ont.). 2026 Jul 03*** epublish ***
Amanda Moreira, Tara Rosewall, Jennifer Dang, Aran Kim, Anna T Santiago, Aruz Mesci, Enrique Gutierrez, Andrew Bayley, Andrew McPartlin, Rachel M Glicksman, Alejandro Berlin, Jeff Winter, Winnie Li, Peter Chung
Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, ON M5G 2C4, Canada., Biostatistics Core, University Health Network, Toronto, ON M5G 1X6, Canada.