• Magnetic resonance guided adaptive Radiotherapy (MRgRT) for localised prostate cancer: The first result from a prospective international registry for the evidence-based Introduction of MRgRT

      Teunissen, F. R.; Willigenburg, T.; Tree, A. C.; Hall, W. A.; Choi, S. L.; Choudhury, Ananya; Christodouleas, J. P.; De Boer, J. C. J.; De Groot-Van Breugel, E. N.; Kerkmeijer, L. G. W.; et al. (2021)
      Introduction & Objectives: Magnetic Resonance (MR) guided adaptive radiotherapy (MRgRT) is a new technique for treatment of localised Prostate Cancer (PCa). MR-guided linear accelerator (MR-Linac) systems have been implemented in radiotherapy departments around the world. However, the theoretical benefits of MRgRT still need to be confirmed in clinical practice. We report the short-term outcomes for the first PCa patients treated within an international consortium on a 1.5T MR-Linac system with ultrahypofractionated radiotherapy. Materials & Methods: Patients treated with 5x7.25 Gray were identified within the registry. Prostate Specific Antigen (PSA), Common Terminology Criteria for Adverse Events (CTCAE) and Patient Reported Outcome (PRO) using the European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLQ)-PR25, EORTC QLQ-C30 and the EuroQol EQ5D-5L were prospectively recorded at baseline and at 3 and 6 months follow-up (FU). Descriptive and pairwise comparative statistics were conducted. Results: One-hundred-and-fifty-six consecutive patients with localised PCa (13.2% low-, 77.2% intermediate-, and 9.6% high-risk [National Comprehensive Cancer Network risk groups]) were included. Thirty-one patients (19.9%) received neoadjuvant Androgen Deprivation Therapy (ADT). A significant decline of PSA in non-ADT patients was observed between baseline (median: 7.8 ng/mL), 3 months FU (median: 2.7 ng/ mL) and 6 months FU (median: 1.7 ng/mL) (p<0.001). No grade ≥3 Genitourinary (GU) and Gastrointestinal (GI) toxicity was reported (table). No significant deterioration of PRO scores were observed. The percentage of men reporting no difficulty getting or maintaining an erection remained constant throughout FU (44.4% at baseline, 40.0% at 3 months FU, and 42.9% at 6 months FU). Conclusions: Ultrahypofractionated 1.5T MR-Linac treatment of localised PCa is effective and safe (no grade ≥3 GU and GI toxicity). In the first 6 months following treatment, patients reported stable erectile function. No significant deterioration of PROs at 3- and 6-months FU was observed.