TY - JOUR
T1 - Hermes
T2 - Randomized Trial of 2-Fraction or 5-Fraction Magnetic Resonance Imaging–Guided Adaptive Prostate Radiation Therapy
AU - Cooper, Sian
AU - Westley, Rosalyne L
AU - Biscombe, Katie
AU - Dunlop, Alex
AU - Mitchell, Adam
AU - Oelfke, Uwe
AU - Nill, Simeon
AU - Manning, Georgina
AU - Burnett, Stephanie
AU - Murray, Julia
AU - Wilkins, Anna
AU - Tunariu, Nina
AU - Price, Derek
AU - Adkins, Aidan
AU - Pathmanathan, Angela
AU - Bucinskaite, Greta
AU - Hafeez, Shaista
AU - Parker, Chris
AU - Ratnakumaran, Ragu
AU - Verkooijen, Helena
AU - Alexander, Sophie
AU - Herbert, Trina
AU - Hall, Emma
AU - Tree, Alison C
N1 - Publisher Copyright:
© 2025 The Author(s)
PY - 2025/11/1
Y1 - 2025/11/1
N2 - OBJECTIVE: To demonstrate safety and feasibility of 2-fraction stereotactic body radiotherapy (SBRT) for prostate cancer.METHODS: This single centre, non-comparative, phase II/R-IDEAL2b trial randomised 46 patients with intermediate/lower high-risk prostate cancer with visible gross tumour volume (GTV) on multiparametric magnetic resonance imaging (MRI) to receive 36.25Gy in 5 fractions over 10 days or 24Gy in 2 fractions with a GTV boost up to 27Gy over 8 days. All treatment was delivered on an MR-linac with daily adaptive replanning. The primary endpoint was acute grade ≥2 (G2+) genitourinary (GU) toxicity (CTCAEv5). Secondary endpoints include gastrointestinal (GI) toxicity and patient reported outcomes.RESULTS: G2+GU acute toxicity was observed in 6/22 (27.3%; 95% CI (0.11-0.50) of patients in the 2-fraction group and 7/24 (29.2%; 95% CI (0.13-0.50) in the 5-fraction group. There were no grade 3(G3) GU toxicities. G2+ urinary frequency rose from 4.5% (1/22) at week 2 to 13.6% (3/22) at week 4 in 2-fraction SBRT. G2+ urinary frequency peaked earlier in 5-fraction SBRT at 16.7% (4/24) in week 2, falling to 12.5% (3/24) at week 4. At 12 weeks, median EPIC-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) and 87.5, IQR 81.3-93.8 in the 5-fraction group. Peak IPSS score was lower in the 2-fraction group (8, IQR 4-11) and 13.5, IQR 10-17) in the 5-fraction group. G2+ GI acute toxicity occurred in 3/24 (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. Randomised trials are warranted to explore late toxicity and biochemical control.
AB - OBJECTIVE: To demonstrate safety and feasibility of 2-fraction stereotactic body radiotherapy (SBRT) for prostate cancer.METHODS: This single centre, non-comparative, phase II/R-IDEAL2b trial randomised 46 patients with intermediate/lower high-risk prostate cancer with visible gross tumour volume (GTV) on multiparametric magnetic resonance imaging (MRI) to receive 36.25Gy in 5 fractions over 10 days or 24Gy in 2 fractions with a GTV boost up to 27Gy over 8 days. All treatment was delivered on an MR-linac with daily adaptive replanning. The primary endpoint was acute grade ≥2 (G2+) genitourinary (GU) toxicity (CTCAEv5). Secondary endpoints include gastrointestinal (GI) toxicity and patient reported outcomes.RESULTS: G2+GU acute toxicity was observed in 6/22 (27.3%; 95% CI (0.11-0.50) of patients in the 2-fraction group and 7/24 (29.2%; 95% CI (0.13-0.50) in the 5-fraction group. There were no grade 3(G3) GU toxicities. G2+ urinary frequency rose from 4.5% (1/22) at week 2 to 13.6% (3/22) at week 4 in 2-fraction SBRT. G2+ urinary frequency peaked earlier in 5-fraction SBRT at 16.7% (4/24) in week 2, falling to 12.5% (3/24) at week 4. At 12 weeks, median EPIC-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) and 87.5, IQR 81.3-93.8 in the 5-fraction group. Peak IPSS score was lower in the 2-fraction group (8, IQR 4-11) and 13.5, IQR 10-17) in the 5-fraction group. G2+ GI acute toxicity occurred in 3/24 (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. Randomised trials are warranted to explore late toxicity and biochemical control.
UR - https://www.scopus.com/pages/publications/105008139504
U2 - 10.1016/j.ijrobp.2025.05.008
DO - 10.1016/j.ijrobp.2025.05.008
M3 - Article
C2 - 40403882
SN - 0360-3016
VL - 123
SP - 773
EP - 782
JO - International journal of radiation oncology, biology, physics
JF - International journal of radiation oncology, biology, physics
IS - 3
ER -