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Prostate
Digital Poster
Clinical
MR-guided SBRT for localized prostate cancer: the first results from the MOMENTUM study
Frederik Teunissen, The Netherlands
PO-1374

Abstract

MR-guided SBRT for localized prostate cancer: the first results from the MOMENTUM study
Authors:

Frederik Teunissen1, Thomas Willigenburg1, Alison Tree2, William Hall3, Seungtaek Choi4, Ananya Choudhury5,6, John Christodouleas7,8, Johannes de Boer1, Eline de Groot-van Breugel1, Linda Kerkmeijer9,1, Floris Pos10, Danny Vesprini11, Helena Verkooijen12, Jochem van der Voort van Zyp1

1University Medical Center Utrecht, Radiation Oncology, Utrecht, The Netherlands; 2The Royal Marsden NHS Foundation Trust and the Institute of Cancer Research, Urological Oncology, London, United Kingdom; 3Medical College of Wisconsin, Radiation Oncology, Milwaukee, USA; 4The University of Texas MD Anderson Cancer Center, Radiation Oncology, Houston, USA; 5University of Manchester, Division of Cancer Sciences, Manchester, United Kingdom; 6The Christie NHS Foundation Trust, Manchester Academic Health Sciences Centre, Clinical Oncology, Manchester, United Kingdom; 7University of Pennsylvania, Radiation Oncology, Philadelphia, USA; 8Elekta AB, Radiation Oncology, Stockholm, Sweden; 9Radboud University Medical Center, Radiation Oncology, Nijmegen, The Netherlands; 10Antoni van Leeuwenhoek Hospital and The Netherlands Cancer Institute, Radiation Oncology, Amsterdam, The Netherlands; 11Sunnybrook Health Sciences Centre, Radiation Oncology, Toronto, Canada; 12University Medical Center Utrecht, Imaging and Oncology Division, Utrecht, The Netherlands

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Purpose or Objective

Magnetic resonance (MR) guided adaptive radiotherapy (MRgRT) is a new technique for treatment of localized 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.

Material and 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 localized 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) or 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).

Table: Clinician-reported toxicity using the CTCAE

The highest grade of a given toxicity that occurred in a time period (3 months FU=0 to 3 months after treatment; 6 months FU=3 to 6 months after treatment). Data available: baseline=68/156 patients; 3 months FU=39/147 patients; 6 months FU=20/124 patients

Conclusion

Ultrahypofractionated 1.5T MR-Linac treatment of localized PCa is effective and safe (no grade ≥3 GU or 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.