HERMES: Randomized Trial of 2-Fraction or 5-Fraction Magnetic Resonance Imaging-Guided Adaptive Prostate Radiation Therapy.
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Authors
Cooper, S
Westley, RL
Biscombe, K
Dunlop, A
Mitchell, A
Oelfke, U
Nill, S
Manning, G
Burnett, S
Murray, J
Wilkins, A
Tunariu, N
Price, D
Adkins, A
Pathmanathan, A
Bucinskaite, G
Hafeez, S
Parker, C
Ratnakumaran, R
Verkooijen, H
Alexander, S
Herbert, T
Hall, E
Tree, AC
Westley, RL
Biscombe, K
Dunlop, A
Mitchell, A
Oelfke, U
Nill, S
Manning, G
Burnett, S
Murray, J
Wilkins, A
Tunariu, N
Price, D
Adkins, A
Pathmanathan, A
Bucinskaite, G
Hafeez, S
Parker, C
Ratnakumaran, R
Verkooijen, H
Alexander, S
Herbert, T
Hall, E
Tree, AC
Document Type
Journal Article
Date
2025-11-01
Date Accepted
2025-05-05
Abstract
PURPOSE: To demonstrate the safety and feasibility of 2-fraction stereotactic body radiation therapy (SBRT) for prostate cancer. METHODS AND MATERIALS: This single-center, noncomparative, phase 2/R-IDEAL 2b trial randomized 46 patients with intermediate/lower high-risk prostate cancer with visible gross tumor volume on multiparametric magnetic resonance imaging to receive 36.25 Gy in 5 fractions over 10 days or 24 Gy in 2 fractions with a gross tumor volume boost up to 27 Gy over 8 days. All treatment was delivered on a magnetic resonance linac with daily adaptive replanning. The primary endpoint was acute grade ≥2 (G2+) genitourinary (GU) toxicity (Common Terminology Criteria for Adverse Events version 5.0). Secondary endpoints include gastrointestinal (GI) toxicity and patient-reported outcomes. RESULTS: G2+ GU acute toxicity was observed in 6 of 22 patients (27.3%; 95% CI, 0.11-0.50) in the 2-fraction group and 7 of 24 patients (29.2%; 95% CI, 0.13-0.50) in the 5-fraction group. There were no grade 3 GU toxicities. G2+ urinary frequency rose from 4.5% (1 of 22) at week 2 to 13.6% (3 of 22) at week 4 in 2-fraction SBRT. G2+ urinary frequency peaked earlier in 5-fraction SBRT at 16.7% (4 of 24) in week 2, falling to 12.5% (3 of 24) at week 4. At 12 weeks, median Expanded Prostate Cancer Index Composite-26 urinary incontinence score was 85.5 (IQR, 75-100) for 2-fraction SBRT and 100 (IQR, 93.8-100) for 5-fraction SBRT. Urinary irritative-obstructive scores were higher at 12 weeks in the 2-fraction group (93.8; IQR, 87.5-100) than in the 5-fraction group (87.5; IQR, 81.3-93.8). Peak International Prostate Symptoms Score was lower in the 2-fraction group (8; IQR, 4-11) than in the 5-fraction group (13.5; IQR, 10-17). G2+ GI acute toxicity occurred in 3 of 24 (6.8%) after 5-fraction SBRT, but none after 2-fraction SBRT. CONCLUSIONS: Acceptable acute GU toxicity was seen after 2-fraction SBRT. Acute GI toxicity was low. Randomized trials are warranted to explore late toxicity and biochemical control.
Citation
International Journal of Radiation Oncology Biology Physics, 2025, pp. S0360-3016(25)00476-6 -
Source Title
International Journal of Radiation Oncology Biology Physics
Publisher
ELSEVIER SCIENCE INC
ISSN
0360-3016
eISSN
1879-355X
Collections
Research Team
Radiother Phys Modelling
Clinic Acad RT Huddart
Directorate RT & Imaging
Clin Trials & Stats Unit
Uro-oncology Trials
Clinic Acad RT Huddart
Directorate RT & Imaging
Clin Trials & Stats Unit
Uro-oncology Trials